[F. Kurr] Handbook of Plastics Failure Analysis(BookZZ.org)

Kurr Handbook of Plastics Failure Analysis

Friedrich Kurr

Handbook of Plastics Failure Analysis

Hanser Publishers, Munich

Hanser Publications, Cincinnati

The Author: Dipl.-Ing. Friedrich Kurr, Weinbergstraße 13, 97259 Greußenheim, Germany

Distributed in North and South America by: Hanser Publications 6915 Valley Avenue, Cincinnati, Ohio 45244-3029, USA Fax: (513) 527-8801 Phone: (513) 527-8977 www.hanserpublications.com Distributed in all other countries by Carl Hanser Verlag Postfach 86 04 20, 81631 München, Germany Fax: +49 (89) 98 48 09 www.hanser-fachbuch.de The use of general descriptive names, trademarks, etc., in this publication, even if the former are not especially identified, is not to be taken as a sign that such names, as understood by the Trade Marks and Merchandise Marks Act, may accordingly be used freely by anyone. While the advice and information in this book are believed to be true and accurate at the date of going to press, neither the authors nor the editors nor the publisher can accept any legal responsibility for any errors or omissions that may be made. The publisher makes no warranty, express or implied, with respect to the material contained herein. The final determination of the suitability of any information for the use contemplated for a given application remains the sole responsibility of the user.

Cataloging-in-Publication Data is on file with the Library of Congress

Bibliografische Information Der Deutschen Bibliothek Die Deutsche Bibliothek verzeichnet diese Publikation in der Deutschen Nationalbibliografie; detaillierte bibliografische Daten sind im Internet über abrufbar. ISBN 978-1-56990-519-7 E-Book ISBN 978-1-56990-545-6 All rights reserved. No part of this book may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying or by any information storage and retrieval system, without permission in writing from the publisher. © Carl Hanser Verlag, Munich 2015 Translation: Olivia Brand Production Management: Jörg Strohbach Coverconcept: Marc Müller-Bremer, www.rebranding.de, München Coverdesign: Stephan Rönigk Layout: Manuela Treindl, Fürth Printed and bound by APPL Group, aprinta druck, Wemding, Germany Printed in Germany

Table of Contents

Preface, Foreword, and Notes for Using Handbook. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

VII

Includes examples for both novices and experts for how to search the figures that show damage patterns with explanatory captions and notes for students on special technical words in the definitions chapter.

1. Technical Glossary of Quality and Damage Terms. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Contains over 2620 technical words, arranged alphabetically, from many areas of plastics technology: references to definitions (Chapter 2), figure numbers of the corresponding quality and damage figures (Chapter 3), the type of plastic, processing, and molded part designation, and the contrast method used.

2. Definitions of Terms in the Technical Glossary. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

75

This chapter contains technical words, arranged alphabetically, from the Technical Glossary with explanations (definitions), connections (arrows) to related terms, damage causes, and damage avoidance.

3. Quality and Damage Figures. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145 As the main part of the book, this chapter contains 588 figures from many areas of plastics technology, with exact explanations of causes of the damage, arranged in 74 historically compiled subchapters. Each page has two figures with biological, electrical, mechanical, physical, or thermal attributes from the areas of plastics processing and application, weathering, colorimetry, and gloss measurement. A “brief expert opinion” is provided, with causes of the damage, damage avoidance, contrast techniques, enlargement, type of plastic, molded part designation, figure numbers, and the keywords from the technical glossary. The analyses were performed with various optical microscopes and a scanning electron microscope.

Appendix. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 441 Table 1: plastics used in the glossary with abbreviations; Table 2: literature references; and Table 3: contrast types in microscopy.

V

Author’s Preface The present figures and knowledge are an accumulation from 35 years of professional experience in microscopic quality and damage analysis. Since there were no textbooks about this subject in the 1970s, practice-related work on plastic processing machinery and attendance at many seminars, trade fairs, conferences, and numerous technical discussions were important for a full understanding of the influences and connections. This was followed by many years at the South German Plastic Processing Center (SKZ) as a teacher with a subsequent specialization in color and gloss tests, in artificial weathering, and in microscopic quality and damage analysis. When I worked at the South German Plastic Processing Center, I taught foreign specialists, gave presentations to experts of the plastics industry, including at the University of Erlangen and the Technical Academy in Esslingen and Sarnen (Switzerland), gave lectures to students at the University of Applied Sciences Würzburg for years, and was involved in the master training in various chambers of commerce and industry in Bavaria and Baden-Württemberg for many years. After retirement, I finally found the time required for writing this encyclopedia. It is a reference book for experts but also a textbook for students. The quality and damage figures (color photographs, color slides) that were chosen for the encyclopedia originate from a historical archive of lectures. The scanned and revised images, which were inspected to determine if they were applicable, include technical terms with figure numbers, captions, and notes on the cause and prevention of damage. These are alphabetically arranged in a glossary and are linked to related technical terms using arrows in the Chapter “Definitions.” The technical terms “microscopic examination” (the connections) and “novice (layperson) terms” are very helpful. Students, for example, can find in their own words the correct technical terms in the table “novice terms.” Quality and damage examples from many areas of plastic processing and application are described in 74 LM (light microscopy) and SEM (scanning electron microscopy) subchapters with industrial technical terms, and any missing information was supplemented. The analyses were performed with various optical microscopes and a scanning electron microscope. Since there are often multiple reasons for an error, all or the most important ones are mentioned. This also facilitates the search for the novice. Many technical terms would have disappeared under a main heading and would have been difficult to find (see → cold flow or → error, rheological) if the book had been written in regular book form. Therefore, the logical conclusion was an alphabetically arranged encyclopedia with division into three main chapters. The technical terms were entered into the Chapter Glossary, their explanations were entered into the Chapter Definitions, and related images with captions are found in the Chapter Quality and Damage Figures. I obtained my expertise, as already mentioned, in seminars, trade fairs, conferences, and in self-study, but particularly through countless discussions with customers, experts, and industry specialists and at the South German Plastic Processing Center. Therefore, references to “who?, what?, and when?” are not possible. The tables, diagrams, and definitions are my own contributions, and the literature in the appendix is only a recommendation. I would like to thank all institute directors, who welcomed my public relations, my clients, and my students for contributing a large amount of information, and all employees of the South German Plastic Processing Center in Würzburg for the lively exchange of information and valuable cooperation. I would also like to express my gratitude to my dear wife Monique and daughter Bricille. The encyclopedia was written working long hours by a practitioner for other practitioners and provides enough knowledge to solve many problems economically and in the shortest possible time, with just a macroscope and microscope, and without expensive high-tech equipment. If it saves you time, my work has been worthwhile. Dipl.-Ing. Friedrich Kurr

VII

Forewordby Prof. Dr.-Ing. Martin Bastian Chief Executive Officer South German Plastic Processing Center (SKZ) Friedrich-Bergius-Ring 22, 97076 Würzburg The worldwide working SKZ is divided into different areas of activity: ••Testing, inspection, and certification of products ••Education and training ••Research and development ••Certification of management systems The author of this encyclopedia, Mr. Friedrich Kurr, was trained as a mechanic, a toolmaker, a mechanical engineering technician, and “Diplomingeniueur (FH)” in mechanical engineering. He was also a teaching and research assistant in Karlsruhe at the University of Applied Science for Construction for Director Prof. Dr. V. Fühner and a night school teacher at regional trade office LGA. He worked at the South German Plastic Processing Center (SKZ) from February 1, 1971, to December 31, 2006. He attended many training courses, including weathering, color and gloss tests, HF and US welding, microscopy, scanning electron microscopy, injection molding, and forming as well as relevant trade shows and conferences to further improve his knowledge. His tasks in the training department as a speaker and course and conference leader included, in particular, the development of teaching programs, speaker choice, correspondence and advertising, and the implementation of training courses and conferences. He proved his professional knowledge and his teaching skills in numerous training courses for vocational teachers, German armed forces, specialists from developing countries, and trade, industry, and plastics industry masters. One of his emphases was to train foreign workers within the scope of German development aid. Mr. Kurr established excellent contacts to the plastic industry through many company visits, field trips, and visits to trade fairs. After moving over to the research and development division, Mr. Kurr expanded the Microscopy Laboratory and performed quality and damage analyses with macroscopes, universal microscopes, and a scanning electron microscope. Over time, more and more types of preparation were used. The number of reports and consultations grew. In this process, a wide range of questions from the areas of weathering, color and gloss tests, window profiles, films, molded parts, large containers, tubes, and HF and US welding were processed. For many years, Mr. Kurr worked as an expert in artificial weathering, microscopic quality and damage analysis, gloss measurement, and visual and spectral color measurement. At the same time he worked as a teacher at the Commercial and Industrial Chamber and as a lecturer at the University of Applied Sciences in Würzburg. Furthermore, he also reported on his extensive knowledge of many areas of plastics engineering in technical papers, training courses, and conferences. After his retirement, Mr. Kurr wrote the present encyclopedia at the request of many, including customers of the SKZ. It contains over 2620 technical terms, which are standard throughout the industry, from quality and damage examples as well as their causes in 588 color images. The technical terms are arranged alphabetically in a glossary, and over 700 of them are explained in the Chapter Definitions. A further subdivision of the color images in the Chapter Quality and Damage Examples in 74 LM and SEM subsections facilitates searching by subject areas. The search examples in the foreword notes and before the respective chapters are useful. In its present form, the encyclopedia is a novelty in the area of quality assurance, and there is no doubt that it will find many interested parties. It was written by a practitioner for other practitioners (experts), but is also recommended for students because of the extensive network of connections with arrows. The causes of damage are explained by the author in an easily comprehensible form without superfluous words. Prof. Dr.-Ing. Martin Bastian www.skz.de/en/

IX

Foreword

Damage Patterns and Finding Causes (Search Examples) Chapter 1 (Glossary) is an alphabetically arranged table of contents of all technical words and figure numbers. Many of these are explained in Chapter 2 (Definitions) and cross-referenced with related terms using arrows (this also includes manufacturing processes and studies that accompany microscopy). This is especially useful for students and experts (who have the knowledge but may not immediately remember all correlations). If a technical term cannot be found in the Chapter Definitions, then the search should be continued in the Chapter Glossary. In both chapters, technical terms that are common in the industry, for example “too-cold molding compound temperature” or “unmelted granulate,” are arranged as follows: “molding compound temperature, too-cold” or “granulate, unmelted.” As an expert, you have some machine, product, and quality catalogs as well as a catalog of errors in mind and therefore already recognize the manufacturing process, the operation sequences, the processing parameters, and flaws (the striking or conspicuous features) of a sample in the visual or microscopic examination. Together with skillful → “questions for the customer” and the instructions in → “microscopic examination” you can then write a report. You do not even need to know the latest type of machine, just the exact working sequences and its effects. With the recognized technical term of the striking feature of a sample, you will find the corresponding figure number (or LM or SEM subchapter) in the Chapter Glossary, the corresponding figure with caption in the Chapter Quality and Damage Figures (Chapter 3), and the explanation in the Chapter Definitions.

Search Example with Technical Terms (Expert Search) Example expert search: You recognize a “pigment conglomerate of 100 microns” in a molded part and find the figure numbers 294 in the Chapter Glossary by searching this word and thus find the figure searched for with explanatory text in the quality and damage chapter. In Chapter Definitions, the technical term is, if desired, explained and further information is given: see also dispersion → pigment streaks, → foreign granulate, → regranulate, → residual granulate, and → streaks.

X

Foreword

Technical Glossary of Quality and Damage Terms No.

1

Technical Term

Figure No.

1825 Pigment conglomerate:

Definition

1826

••up to 70 µm

405

1827

••over 80 µm

Definition

1828


1829

2••fine

Type of Plastic

Processing

Molded Part

Contrast

PE63

Thin section

Water pipe

DL

294

PE

Extrusion

Water pipe

DL

117

PA6.6-GF30

Thin section

Handle

DL

Quality and Damage Figures

3

LM Subchapter: Particles

Figure 294 ••Dispersion, poor, ••Molding compound areas, uncolored, ••Homogenization poor?, ••Carbon black conglomerate to 100 µm, ••Carbon black type is not homogenizable

Figure 294, PE drinking water pipe (M = 25, DL) with an extremely large pigment conglomerate of more than 100 µm in diameter and white flow lines (uncolored molding compound). In the subsequent coloring, a masterbatch was obviously used with an unsuitable type of carbon black, which was not dispersible, even with the best homogenization. The white flow lines developed due to insufficient dispersion of the carbon black, which is included in the masterbatch, and not as initially suspected, by poor homogenization (see also → masterbatch).

Definitions of the Terms in the Technical Glossary

4 5

Technical Terms

Explanation of Terms

Pigment conglomerate

A pigment conglomerate is formed in the molding compound to be colored through an accumulation of color pigments in a poor homogenization and intolerance of the masterbatch carrier or of the color pigments. Good homogenization is impossible in an incompatibility between the masterbatch carrier and the molding compound (see also → dispersion, → foreign granulate, → homogenization, → masterbatch carrier, unsuitable, → pigment streaks, → regranulate, → residual granulate, and → streaks).

XI

Foreword

Search Example with Novice Words (Novice’s Search) Students can also find unknown technical terms, and thus a quick introduction to the subject, in the Chapter Definitions via: “→ Novice Terms” and “→ Microscopic Examination.” These provide cross referencing with arrows through the entire encyclopedia. This chapter is especially suited for learning. It also includes brief descriptions of key manufacturing processes and accompanying microscopy analyses. Since there are often several reasons for an error, the most important or all are mentioned. This facilitates searching. A direct search function by subject is also offered by the LM and SEM subchapters in the Chapter Quality and Damage Figures. There, the figures are arranged by topic. The subchapters are also mentioned in the Chapter Glossary. Example novice’s search: You recognized a “warp” on a PA4.11 hook during the microscopic examination and find the appropriate technical term for the error in the Chapter Definitions under “Novice terms,” “cold flow line (also: cold flow, paint warp, and streaks)” and therefore the figure number in the Chapter Glossary and the associated figure with explanations in the Chapter Quality and Damage Figures. Definitions of the Terms in the Technical Glossary Technical Terms Novice terms

1

2

Explanation of Terms Novice Terms

Place

Technical Terms e = external and i = inner striking features

Thorough mixing

i

Homogenization

Tip

e/i

Fibrils, stretching tip (Fig. 46)

Track

e

Surface error, grinding, damages, mechanical

Warp

e

Cold flow line, cold flow, paint warp, streaks

Technical Glossary of Quality and Damage Terms No.

Technical Term

3

Figure No.

Type of Plastic

Processing

Molded Part

Contrast

158

PC

Injection molding

Water meter indicator

AL

••on PVC

434

PVC

Extrusion

KG elbow

AL

••on SAN

162

SAN

Injection molding

Hook

AL

146

POM

Injection molding

Molded part

AL

0263 Cold flow line(s):

Definition

0264

••at the sprue

0271 0272 0273

••on SAN

4


5

LM Subchapter: Cold flow

Figure 162 ••Cold-flow lines, ••Record grooves, ••Mold temperature or molding compound temperature, too low

Figure 162, SAN hook (M = 30, AL) with cold-flow lines (“record grooves”) on the pinpoint gate. Cause of the complaint was probably a too-cold molding compound temperature during injection. However, because a too-low mold temperature could have also been present, the client received the phone message that both a too-cold mold and molding compound temperature could be to blame. Subsequently, the client pulled back the job (see also Fig. 158 and → cold flow).

Further information can also be found directly before each chapter.

XII

Chapter 1 Technical Glossary of Quality and Damage Terms This chapter includes over 2620 alphabetically arranged technical terms from many areas of plastic technology with references to definitions, figure numbers of the corresponding quality and damage figures, the type of plastic, processing, and mold designation, the contrasting methods used, and 74 LM and SEM subchapters (see the first page of the Chapter Quality and Damage Figures). Since there are often multiple reasons for an error, all or the most important ones are mentioned. This facilitates the search. The numbers after the technical terms are figure numbers, and the associated figures with explanatory text are located in the Chapter Quality and Damage Figures. There the search is implemented with the figure numbers from the technical glossary or directly in the LM and SEM subchapters. Double numbers are located after LM or SEM subchapters (for example, figure numbers 307–311 means SEM subchapter weathering with five figures). The subchapters originate from a historical archive collection that took decades to amass. The yellow-colored cell “definition” in the column “Figure No.” refers to an explanation of the technical term in the Chapter Definitions (where many technical terms are explained). Students will find a quick introduction to the subject through “→ Novice terms” and “→ Microscopic examination” in the Chapter Definitions. They are the source of cross references with arrows through the entire encyclopedia. For the technical terms, the associated figure numbers are found in the Chapter Glossary and the associated figures are in the Chapter Quality and Damage Figures. Experts will find the figure with caption through a technical term and the following figure number in the Chapter Quality and Damage Figures in the Chapter Glossary. An explanation of the technical term can also be found in the Chapter Definitions, if desired. Explanation of color coding used in Column 3 in the Chapter Glossary: Color coding

Explanation

Thumb Index

Technical terms, arranged alphabetically in the Chapter Glossary

Glossary

Figure numbers from 1 to 588, arranged in the Chapter Quality and Damage Figures

Figures & Text

LM subchapter with figure captions in the Chapter Quality and Damage Figures

Figures & Text

SEM subchapter with figure captions in the Chapter Quality and Damage Figures

Figures & Text

Explanation of the technical terms from the Chapter Glossary in Chapter Definitions

Definitions

LM = Light microscopy (or light microscope) SEM = Scanning electron microscopy (or scanning electron microscope)

For search examples, see pages X–XII.

1

Technical Glossary of Quality and Damage Terms

Glossary

No.

Technical Term

Figure No. Type of Plastic Processing

Molded Part

Contrast

Thin section

Window profile

DL

PUR adhesive

Thin section

Window profile

DL

0001 Abrasion

Definition

0002 Achromatic lens

Definition

0003 Additive

Definition

0004 Adhesion

Definition

0005 Adhesion testing for paint

Definition

0006 Adhesive application: defective

169

PUR

0007

040

••missing

0008 Adhesive bonding (LM subchapter)

172–176

0009 Adhesive bonding

Definition

0010 Adhesive drops, penetrative

173

PA6

Adhesion

Handle of car door

AL

0011 Adhesive layer with bubbles

427

PVC-U

Extrusion

Window profile

DL/POL/ /DIC

0012 Adhesive residues and adhesive bead are missing

175

PVC

Adhesion

Bonded socket joint

AL: 1 : 1

0013 Adhesive tape test:

Definition

0014

••for PE

074

PE

Film blowing

Blown film

DL-POL

0015

••for thin sections

108

Thin section

Microtome

Table

Table

0016 Adhesive THF: is missing on the adhesive surface

172

PVC

Adhesion

Bonded socket joint

AL: 1 : 1

0017

389

PVC

Extrusion

Water pipe

AL

PBT

Coating

Fan blade

AL

••turns white with too-early contact with water

0018 After-treatment

Definition

0019 Aged paint system

199

0020 Agglomeration

Definition

0021 Aging:

Definition

0022

••accelerated

492

SAN

Injection molding Cup

DL

0023

••accelerated

493

SAN


DL

0024

••causes of

Definition

0025

••caused by hydrolysis

415

POM

Injection molding Switch housing

AL

0026

••caused by medium and outdoor weathering

310

PUR foam

Foaming

SEM

0027

••caused by moisture and lubricant

416

POM

Injection molding Surface

AL

0028

••experiment

398

SAN

Injection molding Container

AL

0029

••protection against

Definition

0030

••resistance to

Definition

Bumper

0031

••testing is important

022

EPDM

Extrusion

0032

••warpage

570

ABS

Injection molding First aid kit

AL: 1 : 1

0033 Air: entrained, in ABS

227

ABS

Vacuum forming

AL

Window seal Tray

AL

0034

••entrained, in PCTFE

165

PCTFE

Injection molding Bushing

AL

0035

••entrained, in POM

222

POM

Injection molding Rail

AL

0036

••entrained, in PVC

225

PVC

Extrusion

Sheet

AL

0037

••included, in the paint

355

Sheet metal

Coating

Can

SEM

2


No.

Technical Term

Molded Part

Contrast

229

PE/GF-position/PE

Laminating

Slurry containment membrane

AL

0039

••in a C-PVC fitting

230

C-PVC

Extrusion

Fitting

AL

0040

••in Canada balsam

034

POM

Injection molding Ring

AL

0041 Air inclusion: in a weld line

461

PB

Thin section

Mushroom valve

DL

0042

••in a weld line

487

PE100

Flame treatment

Gas pipe

AL

0043

••in a weld zone

439

PE

Filament winding

Pipe sleeve

DL-POL + 

0044

••in PBTP

357

PBTP

Injection molding Part

SEM

0045

••when laminating

229

PE/GF-position/PE

Blown film

AL

Slurry containment film

Glossary


0038 Air bubble:

0046 Air induction: in PP

444

PP

Injection molding Living hinge

DL-POL

0047

231

PB

Electroplating

DL-POL + 

221

POM


AL AL

••in the surface

0048 Air injection

Part

0049 Air streaks:

Definition

0050

165

PCTFE


0051 Aluminum layer: corroded

258

PP-R/AL/PP-R

Extrusion

Composite pipe AL

0052

258

PP-R/AL/PP-R

Extrusion

Composite pipe AL

209

ABS

Vapor deposition, Molded part Al

AL-DIC + 

••in PCTFE ••with transverse cracks

0053 Aluminum metalizing: 0054

••contaminated

278

PE

Injection molding Fan casing

AL-DIC + 

0055

••with yellow top coat

210

SB


AL-DIC + 

POM

Thin section

DL-POL + 

0056 Amorphous plastics (see plastic materials, amorphous)

Definition

0057 Amorphous structure, as opposed to semicrystalline

508

Clutch

0058 Analysis of plastic materials

Definition

0059 Analyzer

Definition

0060 Angle of illumination: acute, shows internal fracture

191

PC

Injection molding Water meter indicator

AL

0061

125

ABS/PC

Injection molding Sheet

AL

DL-POL

••important

0062 Angle of inclination j

Definition

0063 Antioxidants

Definition

0064 Aperture:

Definition

0065

Definition

••numerical

0066 Aperture angle (→ numerical aperture)

Definition

0067 Aperture diaphragm:

Definition

0068

••almost closed

114

POM-GF30

Thin ground sample

0069

••under reflecting light

106

—

Microscope

0070

••under transmitting light

104

—

Microscope

566

PF-GF-Cu

Polished sample

0071 Application error

Cover

AL: 1 : 1 AL: 1 : 1 Clutch lining

AL

3


Glossary

No.

Technical Term


Molded Part

Contrast

0072 Appraiser qualities

Definition

0073 Area of fracture with pigment conglomerates:

351

PVDF

Injection molding Fitting

SEM

0074

••with center vacuole

536

PC

Molded part

AL

0075

••with residual granulate

136

PE

Injection molding Grate

AL AL

Molded part

0076 Artifacts:

Definition

0077

••after weathering

010

PVC-U

Extrusion

0078

••displaying microcracks caused by weathering and the influence of media

007

PA/PTFE


AL: 1 : 1

0079 Assembly line demolding is better

511

PBTB

Injection molding Piston

AL

0080 Assembly of individual parts: provides more knowledge

552

PC

Polished sample

AL

0081

584

PA6

Injection molding Gear rim

PVC + EPDM

Extrusion

—

Microscope

••shows pitch errors

0082 Atomic absorption detects Cu content 259

Window profile

Clutch

AL

Reinforced hose AL

0083 Audit

Definition

0084 Audit report

Definition

0085 Auxiliary material of a laser

Definition

0086 Avoid costs though unnecessary examinations:

274

PA6.6

Electroplating

Clamp

AL

0087

281

PVC U

Extrusion

Pipe

AL-DF

••for a PVC-pipe

AL: 1 : 1

0088 Axial crack in the inner surface of a pipe:

Definition

0089

••after outdoor weathering

019

PE-RT/AL/ PE-RT

Extrusion

Composite pipe AL

0090

••in a pipe after storage at elevated temperature

403

C-PVC

Extrusion

Water pipe

AL

0091 Axial crack with remaining adhesive

389

PVC

Extrusion

Water pipe

AL

0092 Azo crosslinking

Definition

0093 Back injection

Definition

0094 Barrier layer (for O2):

Definition

0095

382

PE-Xc

Extrusion

Heating pipe

AL

PA6

Thin section

Spherulite

DL-POL + 

••with cracks

0096 Beam splitter (and blocking filter)

Definition

0097 Beilby layer

Definition

0098 Best spherulitic texture of PA6

503

0099 Black streaks

Definition

0100 Blackening

Definition

0101 Block ground sample:

Definition

0102

••in a clamping block, rather than scalpel section

097

PE/PA6/PP/ PE

Polishing

Packaging

AL-DIC

0103

••orientation of glass fibers

119

POM-GF30

Block ground sample

Molded part

AL

0104

••with POM-GF30

119

POM-GF30

Block section

Molded part

AL

0105

••with sink mark

517

PE

Injection molding Hand grip

AL

0106

••with unmelted pellets

136

PE


AL

4


No.

Technical Term

Figure No. Type of Plastic Processing Definition

0108

561

••with PBT/PC

0109 Blocking filter

Definition

0110 Blowholes (LM-subchapter)

221–230

0111 Blowholes (SEM-subchapter)

357–357

0112 Blowholes:

Definition

0113

228

••in a deep-drawn part

PBT/PC

Molded Part

Contrast

Block section

Housing

AL-DF

Vacuum forming

Tray

AL

SEM ABS

0114

••in ABS

225

ABS

Extrusion

Blend

AL

0115

••in an ABS blend

226

ABS

Injection molding Blend

AL

0116

••in C-PVC

230

C-PVC

Extrusion

AL

Fitting

0117

••in PBTP

357

PBTP

Injection molding Molded part

SEM

0118

••in POM

221

POM


AL

0119

••in POM

222

POM

Polished sample

AL

Rail

0120

••in PVC

224

PVC

Extrusion

Sheet

AL

0121

••through residual moisture

223

PVC

Extrusion

Sheet

AL

Tray

0122

••through thermal decomposition

228

ABS

Vacuum forming

0123

••when extruding

226

ABS

Injection molding Blend

AL

Blown film

Slurry film

AL

0124 Blow molding

AL

Definition

0125 Blow molding of hollow objects

Definition

0126 Blown film: 3-layered

229

PE/GF-layer/ PE

0127

085

PE

Coextrusion

Carrying bag

AL

0128 Bridge marking for: HDPE

445

HDPE

Extrusion

Sewer pipe

DL

0129

454

PE-X

Extrusion

Pipe

DL

••coextruded ••PE-X

0130 Bridges with: ring binding

032

POM

Injection molding Bridge ring

AL

0131

032

POM


AL AL: 1 : 1

••weld lines

Glossary

0107 Block section:

0132 Bright field contrast AL-HF and DL-HF Definition 0133 Bright field dark field slider

105

—

Microscope

0134 Brittle cracks in roof and welded sheets after outdoor weathering

309

Polymer

Extrusion

Bituminous sheeting Sheet

SEM

0135 Brittle fracture: in ASA

413

ASA

Extrusion

0136

319

PE

Injection molding Rod

SEM

508

POM

Thin section

Clutch

DL-POL + 

POM

Electroplating

Door handle

AL

••in PE

0137 Brittle molded part cross-section 0138 Bubble formation:

Definition

0139

270

••electroplating bubble, opened by scalpel

AL + DL

0140

••electroplating bubble, sharp-edged 271

POM

Electroplating

Door handle

AL

0141

••electroplating bubble, sharp-edged 275

ABS

Electroplating

Cover cap

AL

0142

••in ABS

265

ABS

Electroplating

Cover

AL

0143

••in ABS

266

ABS

Electroplating

Cover

AL

0144

••in ABS

267

ABS

Electroplating

Cover

AL

0145

••in ABS with large sharp-edged bubble

276

ABS

Electroplating

Molded recess

AL

5


No.

Glossary

0146

Technical Term


Molded Part

Contrast

••in ABS/PC caused by part defect

272

Bushing

AL, diagonal

274

0147

••in PA6.6 (in part)

0148

••in PA-GF35 after storage at 285 °C 428

0149

••in PB caused by entrapped air

231

ABS/PC

Electroplating

PA6.6

Electroplating

Clamp

AL

PA-GF35

Polished sample

Glass holder

AL

PB

Electroplating

Molded part

DL-POL + 

0150

••in POM with sharp-edged bubble

270

POM

Preparation

Door handle

AL

0151

••in PP

269

PP

Electroplating

Mounting plate

DL-POL

0152

••large and sharp-edged

276

ABS

Electroplating

Molded recess

AL

0153 Bubble packaging

540

PVC

Bubble technology

Conveyor belt

DL-POL

0154 Bubble: in 1C-lacquer

355

Sheet Metal

Painting

Can

SEM

Painting

0155

••in 2C-lacquer

356

ABS

Cover

SEM

0156

••in laminating film 50 µm

040

PVC-U + PMMA Extrusion

Window profile

DL

0157

••void with bubble/bulge

042

TEEE

Thin section

Line

AL

0158

••void with bubble/bulge

041

TEEE

Extrusion

Compressed air line

AL

SB

Electroplating

Housing

AL

0161 Bubbles, series in electroplating layers 275

ABS

Electroplating

Cover cap

AL

0162 Bulge (warpage)

569

PBT T40

Injection molding Lid

AL: 1 : 1

0163 Burn streak(s):

Definition

0164

458

PC

Injection molding Housing

AL

0159 Bubbles (LM subchapter):

036–042

0160

273

••visible after stripping of electroplating coats

••barely visible

0165

••cloud-like

450

PC

Injection molding Filter housing

DL

0166

••in PC

449

PC


DL

0167

••in SAN

448

SAN

Injection molding Spacer

DL

0168

••in the sprue

264

PP

Pinpoint gate

AL

0169

••in the sprue area

539

ABS

Injection molding Plate

Pinpoint gate

AL

0170

••in the paint

547

—

Coating

0171

••PC

459

PC


AL

0172

••through obstruction of the flow in the extrusion blow head

091

PE

Extrusion blow molding

Multilayer film

DL-POL

Coated surface

AL-DF

0173 Burning (LM subchapter)

537–539

0174 Burr formation

Definition

0175 Butadiene from etched SB

358

SB

Polished sample

Container

SEM

0176 Buttress thread

407

PE

Polished sample

Sealing cap

AL

0177 Ca scale crystals in drinking water at 90 °C

354

Crystals

Drinking water

SEM

0178 Calcium particle:

553

PVC

Extrusion

Water pipe

DL

0179

554

PVC

Extrusion

Water pipe

DL + POL

PE

Preparation

Water pipe

DL

••in PVC

0180 Calendering

Definition

0181 Camera switch

Definition

0182 Canada balsam: 0183

6

Definition st

••thin section placement 1  step

067


No.

Technical Term

Molded Part

Contrast

••thin section placement 2nd step

068

PE

Preparation

Water pipe

DL

0185

••thin section placement 3rd step

069

PE

Preparation

Water pipe

DL

0186

••with air bubbles

034

POM


AL

0187

••with toluene content

411

PS

Thin section

DL

0188 Cancellation of examination due to cost reasons

575

PP-GF40

Injection molding Rope drum

AL

0189 Carbon and graphite particles

328

PTFE

Injection molding Bearing ring

SEM

0190 Carbon black conglomerate: deep black

044

PE80

Extrusion

Pipe

AL

0191

••in fracture centers

404

PE63

Extrusion

Water pipe

AL

0192

••with crack

287

PE

Thin section

Roof sheeting

DL

0193

••very large

Water pipe

DL

Cover

293

PE

Extrusion

0194 Carbon black content 50% in SBR

369

SBR

Injection molding Belt drive

SEM

0195 Carbon black or titanium dioxide?

079

PVC/Acryl

Polished sample

Window profile

AL-DIC

0196 Carbon black streaks:

Definition

0197

044

PE80

Extrusion

Pipe

AL

••and carbon black conglomerate

Glossary


0184

0198

••in a heating element weld line

469

PE

Thin section

Sheet

DL

0199

••strong in PE-X

454

PE-X

Extrusion

Pipe

DL

0200 Carbon fibers CF (see also → reinforcing materials):

341

PPS

Injection molding Control instrument

SEM

0201

••and glass fibers

118

PA6-GF20

Thin section

Fan

DL

0202

••homogeneously distributed

419

PC-CF10

Thin section

Housing

AL

0203 Carbonization through laser

218

PC

Polished sample

Printer lid

AL + DL

0204 Carbon particles:

329

POM


0205

279

PA

Thin section

Film for bearing DL-POL +  ring

PE

Thin section

Sheet

DL

••without matrix bonding

0206 Cause of cracking

Definition

0207 Causes of fracture:

Definition

0208

469

••a weld line of a heating element

0209 Cavitation:

Definition

0210

SEM

••in a PVC pipe

559

PVC

Extrusion

Pipe

AL: 1 : 1

0211 Cavitation areas

564

PP

Compression molding

Membrane

AL

0212 Cavity

Definition

0213 Cell structure in polyether foam, inhomogeneous

420

Polyether PUR

Foaming

Polyether

AL

0214 Center gating

032

POM

Injection molding Web ring

AL

0215 Center vacuole:

Definition

0216

536

••in a mass accumulation

PC

Part

AL

0217

••in PA6.6-GF30

524

PA6.6-GF30

Injection molding Ball socket

0218

••large

306

POM

Thin section

Torsion bar

DL-POL + 

0219

••large

528

POM

Thin section

Torsion bar

DL-POL

0220

••small

525

POM

Injection molding Tie rod

AL

107

—

Microscope

AL: 1 : 1

0221 Centering screws for the field diaphragm

AL

7


Glossary

No.

Technical Term


Molded Part

Contrast

0222 Central gate: large

149

SB

Injection molding Handle

AL

0223

037

PP-GF30

Injection molding Light well

AL

PVC

Adhesion

Socket, adhesive joint

AL: 1 : 1

••with microvacuoles

0224 Chalk in PVC-U

Definition

0225 Chamfer on the pipe is missing

174

0226 Changing temperatures

Definition

0227 Chemical baths

Definition

0228 Chemical crosslinking

Definition

0229 Clamping block method (measuring the film layer thicknesses):

Definition

0230

••a hygienic packaging

097

PE/PA6/PP/ PE


Packaging

AL-DIC

0231

••with scalpel section, instead of thin section

096

PVC

Block section

Film

AL: 1 : 1

PC

Turning

Screw nut for glass holder

DL

0232 Clamping force

Definition

0233 Clamping torque: testing for PC

498

0234

••too high, for PC-CF10

418

PC-CF10


AL

0235

••too high, for HDPE

151

HDPE

Injection molding Screw cap

AL

0236

••too high, for HDPE

178

HDPE

Injection molding Cap

AL

0237

••too high, for PPO

177

PPO

Polished sample

AL

0238 Cleaning agent attack: for PMMA

360

PMMA

Injection molding Probe tip

SEM

0239

006

TPE

Injection molding Bottle cap

AL

Housing

DL

••for TPE

0240 Cleaning agent influence

Definition

0241 Clouding

Definition

0242 Coating

Definition

0243 Coextrusion: of ABS/PC

443

ABS/PC

Coextrusion

0244

Water container

085

PE

Coextrusion

Carrying bag

AL

0245 Cold cracking: in liquid nitrogen

373

PUR

Foaming

Foam

SEM

0246

420

PUR

Foaming

Polyether

AL

••of PE ••of PUR in nitrogen N2

0247 Cold embedding

Definition

0248 Cold flow (LM subchapter)

143–168

0249 Cold flow (SEM subchapter)

350–350

0250 Cold flow

Definition

0251 Cold flow area(s):

Definition

SEM

0252

••close to the sprue

002

PE

Injection molding Nozzle

AL

0253

••extreme

435

PVC

Extrusion

AL

0254

••fine

144

PS

Injection molding Mirror

KG elbow

DL + AL

0255

••on ABS/PC

153

ABS/PC


AL

0256

••on the edges of a gear rim

583

PA6


AL

0257

••particularly pronounced

154

PC

Injection molding Electrical housing

AL-DF

0258

••pronounced

167

POM

Injection molding Gear wheel

AL

0259

••wavy and similar to weld lines

143

PE

Injection molding Reducer

AL

8


No.

Technical Term


Molded Part

Contrast

Definition

0261 Cold flow front: on ABS

147

ABS

Injection molding Vacuum housing

AL

0262

581

ABS/PC

Injection molding Molded recess

AL

••on ABS/PC

0263 Cold flow line(s):

Definition

0264

••at the sprue

158

PC


AL

0265

••concentric

182

PC


AL

0266

••fine

159

PA4.11


AL: 1 : 1

0267

••look like weld lines

157

SAN

Injection molding Door frame

AL

0268

••on one mandrel half

394

POM

Injection molding Catch

AL

0269

••on POM

152

POM


AL

0270

••on PPSU

395

PPSU


AL

0271

••on PVC

434

PVC

Extrusion

0272

••on SAN

162

SAN

Injection molding Hook

KG elbow

AL AL

0273

••on SAN

146

POM


AL

0274

••parabolic

160

PA4.11


DL-POL

0275

••pronounced

168

POM


AL

0276 Cold forming

383

PB


AL

0277 Cold particles

Definition

0278 Cold plugs (flaking):

Definition

0279

••in ABS

148

ABS


AL

0280

••in ASA

324

ASA


SEM

0281

••in PA6

163

PA6


AL: 1 : 1

0282

••in PE

291

PE

Extrusion

AL

0283

••in SB

149

SB


Pipe inside

Glossary

0260 Cold flow errors

AL

0284

••molding compound particle in PS

144

PS


DL + AL

0285

••through shearing

164

PA6


AL

TPE

Injection molding Bracket for bed slats

AL

0293 Color streak effect through knife slits 460

PA11


DL-POL + 

0294 Color streaks: through flow layers

460

PA11


DL-POL + 

0295

••through shear streams

460

PA11


DL-POL + 

0296

••weaken

456

TPE

Injection molding Bracket for bed slats

AL

0286 Cold treatment in thin sections

Definition

0287 Collection chamber

Definition

0288 Color change on the molded part

Definition

0289 Color filter

Definition

0290 Color measuring

Definition

0291 Color pigments reduce the stability:

Definition

0292

456

••as a cause of damage

0297 Coloring (LM subchapter)

079–079

9


Glossary

No.

Technical Term


0298 Coloring:

Definition

0299

454

••poor

PE-X

Extrusion

Molded Part

Contrast

Pipe

DL DL-POL + 

0300

••subsequent for PA

504

PA

Thin section

Molded part

0301

••subsequent for PA6.6

505

PA6.6

Thin section

Molded part

DL-POL + 

0302

••subsequent for PE

127

PE

Extrusion

Water pipe

DL

0303

••subsequent for PP

425

PP

Injection molding Warming tray

AL

0304


426

PP


DL-POL

0305


452

PP

Extrusion

DL

Pipe

0306

••subsequent for TEEE

134

TEEE

Extrusion

Vacuum line

AL

0307

••subsequent

523

POM

Thin section

Bearing shell

DL

0308

••with 3% fuchsine + alcoholacetone 1 : 1

079

PVC/Acryl

Hot plate welding

Window profile

AL-DIC

0309

••with 3% fuchsine + alcoholacetone 1 : 1

489

PA6.6

Injection molding Door handle

AL

0310

••with 3% Victoria blue + alcoholacetone 1 : 1

234

SB

Vacuum forming

Cleaning tray

AL

0311 Combine contrast processes:

Definition

0312

••AL + DL for UP-GF

011

UP-GF

Compression molding

Sheet

AL + DL

0313

••AL-DIC +  for C-PVC (though seemingly nonsensical)

556

C-PVC

Polished sample

Water pipe

AL-DIC

—

Coating

Coated surface

AL

—

Coating

Coated surface

AL-DF

0319 Composite pipe with diffusion barrier 440

PB

Extrusion

Heating pipe

AL

0320 Compressive load through singlelever manual mixing valves

388

C-PVC

Extrusion

Water pipe

AL

0321 Conchoidal fractures: multiple, in a pipe

404

PE63

Extrusion

Water pipe

AL

0322

217

PC

Lasering

Printer cover

AL + DL

384

PMMA

Vacuum forming

Light dome

DL

0314

••choose correctly

546

0315

••correctly chosen

547

0316 Company’s expert report

Definition

0317 Comparison (LM subchapter)

540–556

0318 Compatibilizers

Definition

••through laser

0323 Conchoidal fractures through media influence 0324 Condenser:

Definition

0325

••height adjustment

107

—

Microscope

AL: 1 : 1

0326

••in the universal microscope

104

—

Microscope

AL: 1 : 1

Injection molding Chair

AL

DL

0327 Conditioning in water:

Definition

0328

211

PA6-GF30/PE

0329 Conglomerate (SEM subchapter)

351–351

SEM

0330 Conglomerate:

Definition

0331

290

PB

Extrusion

0332 Contaminated vaporizing chamber

278

PE

Injection molding Air grille

AL-DIC + 

0333 Contamination during installation

248

PP-R

Extrusion

AL

10

••with PE instead of H2O

••burnt

Pipe Fitting


No.

Technical Term


0335 Contrast (LM subchapter)

183–191

0336 Contrast

Definition

0337 Contrast processes in microscopy:

Definition

ABS

Electroplating

Molded Part

Contrast

Cover plate

AL

Glossary

0334 Contamination of electroplating bath 266 by media

0338

••AL in comparison

187

C-PVC

Polished sample

Water pipe

AL

0339

••AL-DIC + -plate in comparison

190

C-PVC

Polished sample

Water pipe

AL-DIC + 

0340

••AL-DIC in comparison

189

C-PVC

Polished sample

Water pipe

AL-DIC

0341

••AL-DIC +  for metallization

209

ABS

Vaporizing

Molded part

AL-DIC + 

0342

••DF-AL in comparison

188

C-PVC

Polished sample

Water pipe

DF-AL

0343

••DL in comparison

183

PP

Thin section

PP sheet

DL

0344

••DL-PH shows fine density differences

184

PP

Thin section

PP sheet

DL-PH

0345

••DL-POL for V-notch

473

PP

Thin section

Weld line

DL + POL

0346

••DL-POL in comparison

185

PP

Thin section

PP sheet

DL-POL

0347

••for ASA

413

ASA

Extrusion

Sheet

AL + DL

0348

••for PP-V-notch

472

PP

Thin section

Weld line

DL

0349

••for PVC

553

PVC

Extrusion

Water pipe

DL

0350

••for PVC

554

PVC

Extrusion

Water pipe

DL + POL

0351 Contrasting with: DIC-DL + aperture diaphragm

169

PVC-U

Extrusion

Window profile

DL-DIC

0352

••DIC-DL + aperture diaphragm + -plate

170

PVC-U

Extrusion

Window profile

DL-DIC + 

0353

••DL-POL + -plate + DIC and aperture diaphragm

171

PVC-U

Thin section

Window profile

DL-POL + 

0354 Control examination with incident light

071

PE

Preparation

Water pipe

DL

0355 Convection oven

Definition

0356 Convection oven for warm storage: of ABS

059

ABS


0357

AL

570

ABS


AL: 1 : 1

0358 Conversion filter

105

—

Microscope

AL: 1 : 1

0359 Conveyor belt, torn

540

PVC

Bubble packaging Conveyer belts

DL-POL

ABS

Injection molding Cover

AL AL

••of ABS

0360 Cooking test:

Definition

0361

203

••creates paint bubbles

0362 Cooling time

Definition

0363 Cooling time, too long

048

PP

Injection blow molding

0364 Cooling, extreme

588

PE


DL AL

Bottle

0365 Copper attack (PP):

235

PP

Extrusion

Water pipe

0366

••in EPDM liner

259

PVC + EPDM

Extrusion

Composite pipe AL

0367

••extreme

251

PE-X

Extrusion

Pipe, crosslinked

AL

0368

••for PP-R

248

PP-R

Extrusion

Fitting

AL

0369

••for PP-R/AL/PP-R

255

PP-R/AL/PP-R

Extrusion

Composite pipe AL

11


Glossary

No.


Molded Part

0370

Technical Term ••for PP-R/AL/PP-R

256

PP-R/AL/PP-R

Extrusion

Composite pipe AL

Contrast

0371

••for PP-R/AL/PP-R

258

PP-R/AL/PP-R

Extrusion

Composite pipe AL

0372

••generates halo-like matrix cracks

257

PP-R/AL/PP-R

Extrusion

Composite pipe AL

0373

••through brass contact

243

PP

Extrusion

Hose

AL

0374 Copper in flow direction before PE-X destroys the matrix

251

PE-X

Extrusion

Pipe, crosslinked

AL

0375 Core displacement: for PA4.11

160

PA4.11


DL-POL

0376

252

PP

Injection molding Protective cover

AL: 1 : 1

0377 Core flowing: for CA

029

CA


AL

0378

••for PA4.11

160

PA4.11


DL-POL

0379

••for SAN with isochromatics

••for PP

142

SAN


DL-POL

0380 Core-foamed PVC-U pipe

423

PVC-U

Polished sample

AL

0381 Core offset (core displacement, molded part offset):

Definition

0382

••at the predetermined breaking point

050

PA6.3

Injection molding Cartridge

AL: 1 : 1

0383

••for PA6.3

049

PA6.3


AL: 1 : 1

0384 Core, plastic:

Pipe

Definition

0385

••for PA6.6-GF25

521

PA6.6-GF25

Fracture surface

Housing

AL

0386

••for PC

536

PC

Molded part

Molded part

AL

0387

••for POM

300

POM

Thin section

Housing

DL-POL + 

0388

••for POM-GF30

119

POM-GF30

Block ground sample

Housing

AL

0389

••for PP

055

PP

Thin section

Molded part

DL-POL

PVC

Extrusion

Corrugated pipe

AL

PVC

Calendering

Flexible sheet for water bed

AL

PE

Extrusion

Sheet

AL

0390 Corona treatment

Definition

0391 Correspondence

Definition

0392 Corrosion

Definition

0393 Corrugator

054

0394 Cost factors

Definition

0395 Counterparty opinion

548

0396 Counter-pressure: increase

Definition

0397

035

••too low

0398 Court opinions

Definition

0399 Cover glass

Definition

0400 Cover glass thickness

Definition

0401 Crack coloring with fuchsine

489

SAN


DL

0402 Crack propagation of fracture parabolas

323

HDPE

Fracture

Water pipe

SEM

0403 Crack structure, ramified

257

PP-R/AL/PP-R

Extrusion

Composite pipe AL

0404 Cracks (LM subchapter)

382–419

0405 Cracks (SEM subchapter)

369–370

0406 Crack(s):

Definition

12

SEM


No. 0407

Technical Term ••and internal fold in a pipe

Molded Part

Contrast

Pipe, crosslinked

SEM

PE-X

Extrusion

0408

••axial cracks

245

PB

Extrusion

Heating pipe

AL

0409

••brittle cracks in the bending area

233

PUR

Extrusion

Air hose

AL

0410

••close to the pipe marking

387

PVC

Extrusion

Water pipe

AL

0411

••concentric

360

PMMA


SEM

0412

••deep, after weathering

022

EPDM

Extrusion

AL

Window seal

Glossary

Figure No. Type of Plastic Processing 327

0413

••fine, incorrectly interpreted

411

PS

Thin section

Cover

DL

0414

••gaping, through unwinding resistance

467

PE

Extrusion

Gas pipe

AL: 1 : 1

0415

••hair cracks through weathering

011

UP-GF

Compression molding

Sheet

AL + DL

0416

••in a heating element welding seam 463

PP

Polished sample

Membrane

AL

0417

••in a sealing cap

406

PE


Sealing cap

AL: 1 : 1

0418

••in an extrusion groove

388

C-PVC

Extrusion

Water pipe

AL

0419

••insular

416

POM


AL

0420

••intercrystalline, between spherulites

507

POM

Thin section

Spherulite

DL-POL + 

0421

••intercrystalline, through spherulite growth

506

POM

Thin section

Spherulite

DL-POL + 

0422

••perpendicular to the extrusion direction

255

PP-R/AL/PP-R

Polished sample

Composite pipe AL

0423

••through hydrolysis

415

POM


AL

0424

••through media attack

243

PP

Extrusion

Hose

AL

0425

••through media influence

498

PC

Turning


DL

0426

••through overload, no cut

549

PVC

Calendering

Water bed membrane

AL

Gas pipe

0427

••through stresses in a welding seam 466

PE100

Extrusion

0428

••through the middle of spherulites

510

PP

Injection molding Part of desalination plant

0429

••underneath the paint coating

261

PC

Thin section

510

PP


DL-POL

PE


SEM

Refined sugar

Convection oven 30 °C

DL-POL

0430 Crack-splitting force divides spherulites 0431 Craze(s):

Definition

0432

370

••in PE

0433 Crockmeter

Definition

0434 Crosslinked plastics (see plastics, crosslinked)

Definition

0435 Crosslinking

Definition

0436 Cross table

Definition

0437 Cryogenic temperature fracture

Definition

0438 Crystal growth: in refined sugar

193

AL DL-POL

Ventilation grille AL

Refined sugar

13


Glossary

No.


Molded Part

Contrast

0439

Technical Term ••in refined sugar

194

Refined sugar


Refined sugar

DL-POL + 

0440

••in vitamin C

192

Ascorbic acid


Vitamin C

DL-POL + 

0441 Crystallite melting temperature range

Definition

0442 Crystallites

Definition

0443 Crystals (LM subchapter)

192–194

0444 Crystals (SEM subchapter):

352–354

SEM

0445

••and fibers of a weathered facade plate

311

Cement bonding

Compression molding

Facing tile

SEM

0446

••of sulfuric acid

335

UP

Filament winding

Acid container

SEM

Membrane

AL

0447 Curing

Definition

0448 Current flashover

080

PP

Compression molding

0449 Customer: communication

162

SAN


AL

0450

581

ABS/PC

Injection molding Recessed grip

AL

PIB

Flat sheet extrusion

Film

AL

Extrusion

Gas pipe

AL

Gas pipe

AL

••feedback

0451 Customer contact

Definition

0452 Customer inquiry

Definition

0453 Cut drag line through a carpet knife

563

0454 Cutting

Definition

0455 Cutting injury: or crack?

543

PE100

0456

544

PE100

Extrusion

0457 Cutting techniques for thin sections

108

Thin sections

Microtome

0458 Cycle time

Definition

0459 Damage (LM subchapter)

557–564

0460 Damage (SEM subchapter)

377–381

••through pipe cutter, no crack

SEM

0461 Damage reenactment (for):

Definition

0462

••EPDM-window sealing

022

EPDM

Extrusion

Window sealing AL

0463

••PE100-gas pipe

544

PE100

Extrusion

Gas pipe

AL

0464

••PE100-gas pipe

545

PE100

Extrusion

Gas pipe

AL

0465

••PUR-spoiler

025

PUR

Casting

Spoiler

AL-DF

0466

••SAN-container

398

SAN


AL

0467

••SB-back cover of television set

241

SB

Injection molding TV rear panel

AL-DF

0468 Damage after mold installation

588

PE


DL

0469 Damage caused by ejection

033

POM


AL

0470 Damages, mechanical:

Definition

0471

••for PE

092

PE


Multilayer film

DL-POL

0472

••for PE

562

PE

Extrusion

Gas pipe

AL

0473 Dark and bright field slider

Definition

0474 Dark field contrast, incident light

Definition

0475 Dark field contrast, transmitted light

Definition

0476 Dead corners in the mold:

Definition

14


No.

Technical Term


Molded Part

Contrast

••for PA6

163

PA6


AL: 1 : 1

0478

••for SAN

448

SAN


DL

0479 Deburring

Definition

0480 Declination angle 

Definition

0481 Decomposition: chemical

242

POM

Injection molding Heavy duty castor

AL

0482

••of silicone through fungi (Candida glabrata)

365

Si

Casting

Artificial epiglottis

SEM

0483

••of silicone through fungi (Candida glabrata)

366

Si

Casting


SEM

0484

••of the surface

415

POM


AL

0485 Decomposition, thermal

Definition

0486 Decorative film

040


0487 Decrease in strength through pigments

351

PVDF


SEM

0488 Defective vision

Definition

0489 Defect through inclusion of particles

292

PVC

Extrusion

Water pipe

AL

PE

Extrusion

Corrugated pipe AL

ABS

Injection molding Mounting plate

AL

0490

••an embossing of a corrugated pipe 084

0491 Deflection

059

0492 Deformation (LM subchapter)

053–063

Window profile

DL

0493 Deformation:

Definition

0494

••of PC

496

PC

Injection molding Runner

AL

0495

••of PE

053

PE

Injection molding Cap

AL

0496

••permanent

551

PA6.6-GF30

Polished sample

Cooling unit

AL

0497

••permanent (dent)

401

PVC-U

Extrusion

Pipe

AL

ABS

Injection molding Snap fit

AL

PBTP


SEM

0498

••plastic

Definition

0499

••smaller

052

0500 Deformation layer

Definition

0501 Degassing insufficient

357

0502 Degradation

Definition

0503

••of PFA

385

PFA

Injection molding Valve

AL

0504

••of PVC

023

PVC

Extrusion

DL

0505 Degree of dryness

Definition

0506 Delamination (LM subchapter)

064–065

0507 Delamination (SEM subchapter)

324–324

0508 Delamination:

Definition

Roof element

Glossary

0477

SEM

0509

••causes

424

PP


AL

0510

••cause for electroplating errors

444

PP

Injection molding Integral hinge

DL-POL

0511


434

PVC

Extrusion

AL

KG elbow

0512

••of ASA

324

ASA


SEM

0513

••of PA-GF35

429

PA-GF35

Polished sample

AL

0514

••of PE

064

PE

Injection molding Head rest

Glass holder

AL

0515

••of PFA

432

PFA

Casting

Pane

AL

0516

••of POM

270

POM

Electroplating

Door handle

AL

15


Glossary

No.

Technical Term


Molded Part

Contrast

0517

••of PP

424

PP


AL

0518

••weld line of an electro fusion socket 476

PB

Socket welding

Socket

AL

Float

AL

0519 Demoldability, poor

560

PBT

Imbedding, EP

0520 Demolding: a little too late

005

PA6

Injection molding Wind shield wiper

AL

0521

••too early

002

PE


AL

0522

••too early

053

PE


AL

0523

••too early

058

POM


AL

0524 Demolding agents: debound

241

ASB


AL-DF

0525

••errors when washing off

203

ABS


AL

0526

••residues in the molded part surface 203

ABS


AL

PE

Injection molding Clip

AL

0527 Demolding error

053

0528 Demolding errors

Definition

0529 Demolding onto conveyor belt:

Definition

0530

537

PA6-GF30

Injection molding Housing ridge

AL

0531 Demolding pins, worn

254

PA6-GF30


AL: 1 : 1

0532 Density determination

Definition

0533 Density differences

184

PP

Thin section

Sheet

DL-PH

0534 Dent

Definition

0535 Deposition

Definition

0536 Depth of field

420

PUR

Foaming

Polyether

AL

0537 Design (LM subchapter)

177–182

0538 Design changes: for PC

182

PC


AL

0539

566

PF-GF-Cu

Polished sample

Clutch lining

AL

PA11

Specimen

Water filter

AL

••preferred over free-fall demolding

••for PF-GF-Cu

0540 Design error:

Definition

0541

530

••for PA11

0542

••for HDPE

178

HDPE, Glass


AL

0543

••for HDPE

179

HDPE


AL

0544 Design instructions through the assembly of single components

552

PC

Polished sample

Clutch

AL

0545 Design of the molded part influences the glass fiber orientation

119

POM-GF30

Block ground sample

Part

AL

0546 Destruction of the surface

Definition

0547 Determination of the layer thickness: 437 at the thin section

PMMA/ABS/ PC

Thin section

Tanning bed

DL

0548

PE/PETP/PA

Polished sample

Composite film

AL

••at the polish (composite film)

436

0549 Determine crystallinity

Definition

0550 Determine filler and reinforcing materials

Definition

0551 Determine foreign material

Definition

0552 Determine melting point

Definition

0553 Determine molecular weight

Definition

0554 Determine monomers

Definition

16


No.

Technical Term


0556 Determine polymer blends

Definition

0557 Determine thermal stability

Definition

0558 DIC prism

Definition

0559 DIC slider

Definition

0560 Diesel effect:

Definition

0561

537

••for PA6-GF30

Molded Part

Contrast

Glossary

0555 Determine plasticizers

PA6-GF30


AL

0562

••for PA6-GF30

538

PA6-GF30


AL

0563

••for PC

457

PC


AL

0564

••for PC

459

PC


AL

0565

••for SAN

448

SAN


DL

ASB


AL-DF

PVC


DL

0566 Differential interference contrast AL-DIC and DL-DIC

Definition

0567 Diffraction angle 

Definition

0568 Diffusion adhesives

Definition

0569 Diffusion barrier

Definition

0570 Diffusion layer (LM subchapter)

066–066

0571 Diffusion of release agents

241

0572 Dimensional error

Definition

0573 Dioptric compensation

Definition

0574 Discharge (LM subchapter)

080–081

0575 Discoloration

Definition

0576 Discoloration, brown/red, with PVC

Definition

0577 Discoloration, browning, natural weathering

023

Roofing

0578 Dismounting: is advisable

584

PA6


AL

0579

249

PVC

Extrusion

Shutter

AL: 1 : 1

Water pipe

••is important to find damages

0580 Dispersion:

Definition

0581

294

PE

Extrusion

0582 Displacement of the molded part

049

PA6.3


AL: 1 : 1

0583 Dissecting needle

Definition

0584 Dissolving of plastics:

Definition

0585

••in acetone

111

PA6.6


DL

0586

••of a vicryl surgical thread

326

Vicryl

Spinning

SEM

PA6


AL

••poor

Suture material

DL

0587 Distinctive features

Definition

0588 Dividing error at a gear wheel

582

0589 DMA analysis

Definition

0590 Door handle, ABS/PC, insufficient injection

579

ABS/PC


AL

0591 Double lining of embossing films, accidental

438

PVC-U

Thin section

DL-DIC + 

0592 Double refraction

Definition

0593 Drawing blend

Definition

0594 Drying time

Definition

Window profile

17


Glossary

No.

Technical Term


0595 DSC analysis

Definition

0596 Duty of care, neglected

543

Molded Part

Contrast

PE100

Extrusion

Gas pipe

AL


Multilayer film

DL-POL

0597 Dwell time:

Definition

0598

••too long for PE

091

PE

0599

••too long for SAN

448

SAN


DL

0600 Earth pressure deformation with axial cracks

298

HDPE

Extrusion

AL

0601 Edge bead, similar to overmolding

155

PS

Injection molding Rocker switch

AL

0602 Edge effect in the SEM:

Definition

0603

307

PP-UV stable

Injection molding Lawn chair, UV stabilized

SEM

124

PP


AL

0605 Effect paint: with solvent penetration 207

PA/PE

Injection molding Hub cap

DL

0606

PA/PE

Polished sample

DL

••In PP-UV stable

0604 Effect of unmelted pellets ••AL-effect paint

0607 Efflorescence

262

Water pipe

Hub cap

Definition

0608 Ejection (demolding):

Definition

0609

••too early

053

PE

Injection molding Sealing cap

AL

0610 Ejector load, adverse

560

PBT

Injection molding Windshield wiper

AL

0611 Ejector mark:

Definition

0612

058

POM


AL

••deep

0613

••with PA6-GF30

253

PA6-GF30


AL: 1 : 1

0614

••with PC

457

PC


AL

0615 Ejector mark: caused by extreme cooling

588

PE


DL

0616

••deliberate

386

ABS

Injection molding Siphon housing

AL

0617

••double

560

PBT

Injection molding Windshield wiper

AL

0618 Ejector pin used for cooling

588

PE


DL

0619 Elastomer(s)

Definition

0620 Elastomer, Thermoplastic, TPE

Definition

0621 Electro-fitting diagonally welded

474

PE

Socket welding

Water pipe

AL

0622 Electro-fitting weld line: poor weld line contour

475

PB

Socket welding

Socket

AL

0623

••settle the question of blame

543

PE100

Extrusion

Gas pipe

AL

0624

••with crack

465

PE100

Socket welding

Gas pipe

AL

0625

••with crack at tube intake without guide rolls

466

PE100

Socket welding

Gas pipe

AL

0626

••with delamination

476

PB

Peel test

Socket

AL

0627 Electron beam (SEM subchapter)

325–325

SEM

0628 Electron beam attack

325

PEEK

Injection molding Fastener

SEM

0629 Electroplating:

Definition

0630

275

ABS

Electroplating

AL

18

••bubbles with sharp bubble edge

Cover


No. 0631

Technical Term


Molded Part

Contrast

271

Door handle

AL

POM

Electroplating

0632 Electroplating error:

Definition

0633

••electroplating layer is injured

059

ABS

Injection molding Blank

AL

0634

••electroplating layers are brittle/ hard

270

POM


AL

0635

••electroplating shadow through mounting that is too dense

277

ABS

Electroplating

AL

282

Cover

0636

••layer residues

POM-GF30

Injection molding Electric switch

AL

0637

••only the palladium layer is present 277

ABS

Electroplating

Cover

AL

0638

••open bubbles with a scalpel

270

POM

Electroplating

Door handle

AL

0639

••palladium, Cu, Ni, Cr

269

PP

Thin section

Base plate

DL-POL

0640

••palladium, Cu, Ni, Cr removing

272

ABS/PC

Electroplating

Bushing

AL, diagonal

276

0641

••systematic error

0642

••through bubbles in the molded part 274

0643

••through mass swivel with air induction

0644

Glossary

••sharp bubble edge in the 1st metal layer

ABS

Electroplating

Cover

AL

PA6.6

Electroplating

Bracket

AL

231

PB

Electroplating

Part

DL-POL + 

••through molded part errors

272

ABS/PC

Electroplating

Bushing

AL, diagonal

0645

••with bubble formation

269

0646

••with bubble formation, molded part 266 is error-free

PP

Electroplating

Base plate

DL-POL

ABS

Electroplating

Cover

AL

0647

••with bubbles

265

ABS

Electroplating

Cover

AL

0648

••with bubbles

266

ABS

Electroplating

Cover

AL

0649

••with fine cracks

060

ABS


AL

0650

••with flat bubble

270

POM

Preparation

Door handle

AL

0651

••with stains, which are 50 µm in size 267

ABS

Electroplating

Cover

AL

0652

••with very large sharp-edged bubble 276

ABS

Electroplating

Molded recess

AL

PB

Electroplating

Molded part

DL-POL + 

PE

Vapor deposition

Ventilation grille AL-DIC + 

0653 Electroplating liquids, displaced

231

0654 Electrostatic charge:

Definition

0655

278

••by friction

0656 Element determination:

Definition

0657

268

ABS

Electroplating

ABS cover

AL

0658 Elongation flow (glass fiber)

119

POM-GF30

Block ground sample

Molded part

AL

0659 Embedding (LM subchapter)

073–078

0660 Embedding:

Definition

••with ESCA analysis

0661

••in vacuum

Definition

0662

••of a piston ring in epoxy resin

075

PA/PTFE

Thin section

Piston ring

AL

0663

••of a piston ring in epoxy resin

076

PA/PTFE

Thin section

Piston ring

DL-POL

0664

••of a sealing seam in epoxy resin

073

PE

Polished sample

Blown film

DL-POL

0665

••of an ultrasonic weld line in epoxy 478 resin

PP

Imbedding, EP

Float

AL

19


No.

Glossary

0666

Technical Term ••when plane-parallel edges are missing


0667 Embedding media

Definition

0668 Embossing foil

427

0669 Embossing offset:

Definition

0670

054

••in a corrugated pipe

Molded Part

Contrast

PA/PTFE

Block ground sample

Piston ring

AL

PVC-U

Extrusion

Window profile

DL/POL/ /DIC

PVC

Extrusion

Corrugated pipe

AL

0671 Embrittlement:

Definition

0672

••in polymer-roof welded sheets

309

Polymer

Extrusion

Roof sheeting

SEM

0673

••of an amorphous marginal zone

302

POM

Thin section

Acme thread

DL-POL + 

0674

••of an amorphous marginal zone

300

POM

Thin section

Housing

DL-POL + 

PA6.6

Injection molding Push rod

AL

PFA


AL DL-POL + 

0675

••of PA6.6

393

0676

••of PFA

Definition

0677

••of PFA

385

0678

••of POM

507

POM

Thin section

Spherulite

0679

••of POM

508

POM

Thin section

Clutch

DL-POL + 

0680

••of PVC

023

PVC


Roof element

DL

0681

••of PVC

Definition

0682

••through thermal decomposition

023

PVC

Extrusion

Roofing element

DL

0683

••with cracks

Window seal

AL

022

EPDM

Extrusion

0684 End of the flow path: glass fibers in

338

PA-GF20

Injection molding Bearing seat

SEM

0685

••in cold molding compound

579

ABS/PC


AL

0686

••not reached

574

PC


AL

0687 Energy director, residuals

479

PP

Embedding EP

Float

DL-POL

0688 Equipment (LM subchapter)

103–110

0689 Erosion of the grain of sand

559

PVC

Extrusion

Pipe

AL: 1 : 1

0690 Erosion on the molded part surface through fluoride treatment

254

PA6-GF30


AL: 1 : 1

0691 Error: during painting

Definition

0692

••during washing off the release agent

203

ABS


AL

0693

••rheological

Definition

0694

••systematic during electroplating

266

ABS

Electroplating

AL

0695

••systematic during painting

197

PA6

Injection molding Frame for interior door handle

AL

SB


AL-DF

PS

Thin section

DL

0696 Error adjustment (influence of media) 241 0697 Error influences, human

Definition

0698 Errors of interpretation of cracks

411

0699 ESCA analysis for the determination of elements:

Definition

20

Cover

Cover


No. 0700

Technical Term ••for ABS

Molded Part

Contrast

ABS cover

AL

ABS

Electroplating

Definition

0702

••with 100% acetic acid

442

Zn

Etching

Cast sleeve

DF-AL

0703

••with 30% nitric acid

441

Zn

Etching

Cast sleeve

DF-AL

0704

••with chromium-sulfuric acid

358

SB


SEM

0705 Evidence order

Glossary

0701 Etching:


Definition

0706 Examination after order confirmation Definition 0707 Examination, comparing, for:

Definition

0708

••ABS cover

585

ABS


AL

0709

••C-PVC conveyor belts

540

PVC


DL-POL

0710

••C-PVC pipes

555

C-PVC

Extrusion

Water pipe

AL

0711

••C-PVC pipes

556

C-PVC

Polished sample

Water pipe

AL-DIC + 

0712

••isochromatics (few)

238

SAN

Comparison

Mixing cup

DL-POL

0713

••isochromatics (many)

239

SAN

Comparison

Mixing cup

DL-POL

0714

••PA6.6-GF30 polished samples

550

PA6.6-GF30

Polished sample

Cooling unit

AL

0715

••PA6.6-GF30 polished samples

551

PA6.6-GF30

Polished sample

Cooling unit

AL

0716

••PA6-GF15 clamping parts

180

PA6-GF15

Polished sample

Clamping mechanism

AL

0717

••PA6-GF15 clamping parts

181

PA6-GF15

Polished sample

Clamping mechanism

AL

0718

••paint surfaces

546

—

Coating

Coated surface

AL

0719

••paint surfaces

547

—

Coating

Coated surface

AL-DF

0720

••PA-PTFE piston ring

541

PA/PTFE

Injection molding Piston ring

AL

0721

••PA-PTFE piston ring

542

PA/PTFE


AL

0722

••PC facade plates

016

PC

Injection molding Facing tile

DL-DIC

0723

••PC telephone housing

586

PC

Injection molding Cell phone housing

AL

0724

••PC telephone housing

587

PC

Injection molding Cell phone housing

AL

0725

••PE sealing caps (Figs. 406–410)

406

PE


Sealing cap

AL

0726

••PE100 gas pipe, crack or cut?

543

PE100

Extrusion

Gas pipe

AL

0727


544

PE100

Extrusion

Gas pipe

AL

0728


545

PE100

Extrusion

Gas pipe

AL

557

0729

••LDPE, hole or stab injury?

0730

••LDPE, stretch film with stab injury? 558

0731

••PF-GF-Cu polished samples

565

Blown film

Stretch film

AL

LDPE

Blown film

Stretch film

AL

PF-GF-Cu

Polished sample

Clutch lining

AL

Clutch lining

0732

••PF-GF-Cu polished samples

566

PF-GF-Cu

Polished sample

0733

••PIB-film with cutting damages

563

PIB

Flat film extrusion Film

AL

0734

••PLA98 implant pins (Figs. 342–349)

342

PLA98

Medical comparison

Implant pin

SEM

0735

••polished sample (see also Fig. 556) 555

C-PVC

Polished sample

Water pipe

AL-DIC

0736

••POM ultrasonic welding seams

POM

Ultrasonic welding

Molded part

DL-POL + 

481

AL

21


No.

Glossary

0737

Technical Term ••POM ultrasonic welding seams


Molded Part

Contrast

482

Molded part

DL-POL + 

POM

Ultrasonic welding

0738

••PP T40 housing

567

PP T40


DL

0739

••PP welding seams

462

PP

Heated tool welding

Membrane

AL

0740

••PP welding seams

463

PP

Heated tool welding

Membrane

AL

0741

••PVC thin sections

477

PVC

Thin section

Window

AL

0742

••PVC water bed, crack or cut?

548

PVC

Calendering

Water bed membrane

AL

0743

••PVC water bed, crack or cut?

549

PVC

Calendering

Water bed membrane

AL

0744

••PVC-pipes

553

PVC

Extrusion

Water pipe

DL

0745

••PVC-pipes

554

PVC

Extrusion

Water pipe

DL-POL

0746

••SAN bushings (Figs. 490–493)

490

SAN

Injection molding Nut

DL

0747

••SB TV rear panel

241

SB


AL-DF

0748

••some contrasting methods (Figs. 183–186)

183

PP

Thin section

Sheet, PP

DL

0749 Examination devices, microscopic

Definition

0750 Examination methods, microscopic

Definition

0751 Examination, microscopic

Definition

0752 Examination, visual

Definition

0753 Examine the flow behavior

Definition

0754 Examine titanium dioxide in incident light

079

PVC/Acryl

Polished sample

Window profile

AL-DIC

0755 Excessive elongation of material in a pipe (pressure test)

397

PP

Extrusion

Pipe

AL

0756 Expanding moment

059

ABS


AL

0757 Expansion tension: for PC

552

PC

Polished sample

AL

0758

490

SAN


DL

••for SAN

Clutch

0759 Expert opinion (simple)

Definition

0760 Exposure test (impact assessment)

Definition

0761 Extrusion (LM subchapter)

082–085

0762 Extrusion

Definition

0763 Extrusion blow molding (with): 11 layers (→ film blowing)

098

—


Coating layer

DL-POL + AL

0764

••7 layers

097

PE/PA6/PP/ PE

Polishing

Packaging

AL-DIC

0765

••burn streaks

091

PE


Multilayer film

DL-POL

0766

••film fold

094

PE


Multilayer film

DL-POL

0767

••film specks in PE film

095

PE


Multilayer film

DL-POL

0768

••flow hindrance in the extruder blow head

091

PE


Multilayer film

DL-POL

22


No.

Technical Term

Molded Part

Contrast

••globule

087

PE


Multilayer film

DL-POL

0770

••layer fracture

089

PE


Multilayer film

DL-POL

0771

••light transmission, decreasing

023

PVC


Roofing element

DL

0772

••melt break

090

PE


Multilayer film

DL-POL

0773

••melting zone, wide

095

PE


Film

DL + AL

0774

••microbiological growth on a PE-film

362

PE


Film

SEM

0775

••PE-oil container wall

422

PE


Wall of oil reservoir

AL

0776

••plastic particles, nonmelting

086

PE


Multilayer film

DL-POL

0777

••single-layer film

092

PE


Multilayer film

DL-POL

0778

••three-layer transparent film and hole

088

PE


Multilayer film

DL-POL

0779 Extrusion, cold

502

PP

Thin section

Water pipe

DL-POL + 

0780 Eye

Definition

0781 Eyeglass wearers

Definition

0782 Facade sheet with UV-stabilizer

016

PC


DL-DIC

0783 Fading:

Definition

0784

AL

••after weathering (long)

022

EPDM

Extrusion

0785 Failure area (cross section): in PETP

045

PETP


AL-DF

0786

AL

Window seal

500

HDPE

Extrusion

0787 Fatigue failure

320

PVC


SEM

0788 Feed section, air which is carried along from the

222

POM

Polished sample

AL

0789 Fibrils (stretched tip):

Definition

0790

••are vertically in the center of the fracture

046

PETP


AL-DF

0791

••ductile

036

PP-GF30


AL

0792

••in a craze

370

PE


SEM

••in HDPE

Water pipe Rail

0793

••in the fracture flank (PBTB)

531

PBTB


AL

0794

••in the fracture flank (PE)

317

PE


SEM

0795

••in the normal stress zone

316

PB

Extrusion

Pipe

SEM

0796

••running diagonally in the further developed crack

322

SB

Overload fracture

Housing

SEM

0797

••shrinkage fibrils

376

PPO

Molded part

SEM

0798

••through stresses in the molded part

135

PA

0799 Field glasses, principle for the stereomicroscope

Definition

0800 Field lens

Definition


Glossary


0769

DL-POL + 

23


Glossary

No.

Technical Term


0801 Field of vision, black

Definition

0802 Filament (SEM subchapter)

326–326

SEM

0803 Filler materials (SEM subchapter)

328–328

SEM

0804 Filler materials and reinforcing materials:

Definition

0805

••chalk

337

0806

••examine

Definition

PVC-GF15

Molded Part


Contrast

SEM

0807

••kaolin

339

FEP


SEM

0808

••reinforcing materials

330

PA

Injection molding Clamp

SEM

0809

••test in elastomers

Definition

0810

••test in synthetic rubbers

Definition

0811 Filling study(ies)

Definition

0812

137

PE


Bottle

DL-POL

0813 Film: with hole or stab injury?:

557

LDPE

Blown film

Stretch film

AL

0814

558

LDPE

Blown film

Stretch film

AL

••filling study

••with stab injury

0815 Film blowing

Definition

0816 Film gate

163

PA6


AL: 1 : 1

0817 Film layer thickness, not to measure on thin sections

096

PVC

Block section

AL: 1 : 1

0818 Film-like particle in the molded part

284

PS


DL-POL + 

0819 Film manufacture

Definition

0820 Film scraper: in a single-layer film

092

PE


Multilayer film

DL-POL

0821

093

PE


Multilayer film

AL + DL + POL

0822 Film speck: in PE film

095

PE


Multilayer film

DL-POL

0823

095

PE


Film

DL + AL

PP

Injection molding Protective cover AL: 1 : 1

PC

Injection molding Electronics housing

AL-DF

AL

••intentionally

••though wide melting zone

0824 Films (LM subchapter)

086–098

0825 Filter

Definition

0826 Fingerprints with parallel cracks

252

0827 Fire prevention equipment:

Definition

0828

154

••for PC

Film

0829 Fisheye

Definition

0830 Fishtail nozzle

Definition

0831 Flake, paint defects

199

PBT

Coating

0832 Flaking (cold plugs)

147

ABS


AL

0833 Flame retardant

211

PA6-GF30/PE


AL

0834 Flame treatment:

Definition

Fan blade

0835

••by Bunsen burner

486

PE100

Extrusion

Gas pipe

AL

0836

••by gas flame

487

PE100

Flame treatment

Gas pipe

AL

24


No.

Technical Term

Molded Part

Contrast

043

PVC

Extrusion

Water pipe

AL

0838 Flexing work with overheating

242

POM

Injection molding Castor, POM

AL

0839 Flocking

Definition

0840 Flow division

116

PC-GF35

Thin ground sample

Part

DL-POL

0841 Flow fronts are visible: in polarized transmitted light

138

SAN


DL-POL

0842

139

SAN


DL-POL

0843 Flow hindrance in the extruder blow head

091

PE


DL-POL

0844 Flow lines:

Definition

0845

••through isochromatics

Multilayer film

Glossary


0837 Flanks of the crack with crack areas

123

PETP


DL-POL + 

0846 Flow parabolas, V-shaped

321

SB

Overload fracture Housing

SEM

0847 Flow paths, different

003

PA/PTFE


AL: 1 : 1

0848 Flow resistance

160

PA4.11


DL-POL

0849 Flow resistances, high

116

PC-GF35

Thin ground sample

Molded part

DL-POL

••on a housing surface

0850 Flow seam:

Definition

0851

••gaping

399

C-PVC

Extrusion

Fitting

AL

0852

••opened

400

C-PVC

Extrusion

Fitting

AL

0853 Flow shadows

116

PC-GF35

Thin ground sample

Molded part

DL-POL

0854 Flow streaks

Definition

0855 Flow structure in the surface

273

SB

Electroplating

Housing

AL

0856 Flow viscosity (molding compound)

146

POM


AL

0857 Flow viscosity, high

168

POM


AL

0858 Flow, hardly visible

458

PC


AL

0859 Flowability:

Definition

0860

••of the molding compound

145

PE


AL

0861

••poor

575

PP-GF40


AL

0862

••reduced

532

PP-GF40


AL

0863 Fluorescence contrast AL-FL and DL-FL

Definition

0864 Fluorination:

Definition

0865

••for PA6-GF30

253

PA6-GF30


AL: 1 : 1

0866

••for PA6-GF30

254

PA6-GF30


AL: 1 : 1

0867 Foam (LM subchapter):

420–420

0868

••closed-celled

371

PUR

Foaming

Foam

SEM

0869

••open-celled

374

PUR

Foaming

Mattress

SEM

0870 Foam bridges

371

PUR

Foaming

Foam

SEM

0871 Foam filter with 1 µm pores

374

PTFE

Compression molding

Filter screen

SEM

0872 Foaming

Definition

0873 Foams (SEM subchapter)

371–374

SEM

0874 Focusing to the base of the vacuole

535

PPS-GFM

Injection molding Pipe sleeve

AL

25


Glossary

No.

Technical Term


0875 Following shot

Definition

0876 Foreign granulate:

Definition

Molded Part

Contrast

0877

••hard to melt

124

PP

Polished sample

0878

••in PP

364

PP


SEM

0879

••is not a metal particles

125

ABS/PC


AL

PE

Extrusion

Water pipe

DL-POL + 

Pipe

0880 Foreign material:

Definition

0881

••determine

Definition

0882

••in PE

451

Container

AL

0883

••in PP

452

PP

Extrusion

0884

••in SB

322

SB


SEM

DL

0885 Foreign particle:

Definition

0886

••globule (foreign particle)

086

PE


Multilayer film

DL-POL

0887


461

PB

Thin section

Mushroom valve

DL

0888

••in PVC-U

281

PVC U

Extrusion

Pipe

AL-DF

0889

••transparent (IR and DSC analysis)

289

PP/PE-Blend


AL-DF

0890

••transparent, in PP/PE-polymer blend

288

PP/PE-Blend


AL-DF

0891

••underneath the molded part surface

286

PP


AL-DF

0892

••undesired

312

SB

Injection molding Tensile rod

SEM

0893

••with “badly welded” edges

038

PP-GF30

Polished sample

AL

PP-UV stable

Injection molding Lounger, UV stabilized

SEM

AL

0894 Forming

Definition

0895 Fovea

Definition

0896 Fracture (chemical, mechanical)

Definition

0897 Fracture after weathering

307

Light well

0898 Fracture center:

Definition

0899

••in a burst pipe with grime conglomerate

047

C-PVC

Extrusion

0900

••in PPE

391

PPE


Pipe

AL

0901

••in SB

321

SB


SEM

0902

••in SB

322

SB


SEM

0903

••with beginning of a crack, fibrils and crack front

046

PETP


AL-DF

0904

••with further tear zone

313

POM

Injection molding Tensile bar

SEM

0905 Fracture centers

045

PETP


AL-DF

0906 Fracture edge cracks

Definition

0907 Fracture edge with the center of the fracture:

257

PP-R/AL/PP-R

Extrusion

Composite pipe AL

0908

••with fibrils

316

PB

Extrusion

Pipe

0909

••with fibrils

317

PE


0910 Fracture lines

315

PP


SEM

0911 Fracture parabolas:

392

PVC


AL

26

SEM SEM


No.

Technical Term


Molded Part

Contrast

••concentric

391

PPE


AL

0913

••open in the direction of the tear

323

HDPE

Fracture

Water pipe

SEM

PE

Polished sample

Sealing plug

AL

0914 Fracture stages

Definition

0915 Fracture surface: polished

130

0916

••with blowholes

227

ABS

Vacuum forming

Tray

AL

0917

••with dull spots

044

PE80

Extrusion

Pipe

AL

0918

••with giant vacuole

531

PBTB


AL

0919

••with tough molding compound flow 521

PA6.6-GF25

Fracture surface

AL

Housing

Glossary

0912

0920 Fracture test

Definition

0921 Fracture types (Author definitions)

Definition

0922 Fracture, nick (surface)

Definition

0923 Fractures (LM subchapters)

043–052

0924 Fractures (SEM subchapters)

312–323

SEM

0925 Fracturing: after crack development

491

SAN


DL

0926

••at room and low temperature

Definition

0927

••brittle fracture

077

PA

Embedding

DL-POL + 

0928

••caused by sharp corner

180

PA6-GF15

Injection molding Clamp part

Electric cable duct

AL

0929

••intended

120

PBT

Injection molding Screen

AL

0930

••manual

342

PLA98

Medical

Implant pin

SEM

0931

••with PA11

530

PA11

Specimen

Water filter

AL

0932 Free-fall demolding:

Definition

0933

••is unfavorable

511

PBTB


AL

0934

••is worse than conveyor belt demolding

537

PA6-GF30


AL

PC

Thin section

Tooth fracture

DL-POL + 

Pinpoint gate

AL

0935 Free-jet formation:

Definition

0936

099

••in PC

0937 Freezing in liquid nitrogen

Definition

0938 Friction and local overheating:

Definition

0939

••in the hot runner pinpoint gating

264

PP

Pinpoint gate

0940

••through fast injection

448

SAN


DL

0941 Friction welding (vibration friction welding)

065

PC

Vacuum forming

Sky light

AL

0942 Friction welding seam with radial groove

468

ASA

Friction welding

Housing

AL

0943 Frictional electricity: for PE gas pipe

081

PE

Extrusion

Gas pipe

AL

0944

080

PP

Compression molding

Membrane

AL

••for PP-membrane

0945 Front lens

Definition

0946 FTIR analysis

Definition

0947 Fuchsine (coloring agent):

Definition

0948

••raises the contrast of cracks

489

PA6.6


AL

0949

••dispersion

260

PA


AL

27


Glossary

No.

Technical Term


Molded Part

Contrast

Casting


AL

Si

Casting


SEM

368

Fungus

—

Tempeh (soy dish)

SEM

0950 Fungi (LM subchapter)

295–298

0951 Fungi (SEM subchapter)

365–368

SEM

0952 Fungi: Candida glabrata on silicone

296

SI

0953

••Candida glabrata, juvenile form

367

0954

••Rhizopus oligosporus

0955

••yellow, on teakwood

297

Teak

Wood treatment

Teak bench

AL

0956 Fungus threads, white

298

HDPE

Extrusion

Water pipe

AL

0957 Gas and particle formation during the laser process

220

POM

Thin section

Push button

DL

0958 Gate:

Definition

0959

003

PA/PTFE


AL: 1 : 1

••polish

0960 Gate grooves, concentric

Definition

0961 Gate stresses

001

PP

Injection molding Water bell

AL

0962 Gate stringer/filament

002

PE

Injection molding Water bell

AL

0963 GC analysis

Definition

0964 Gear wheel with: deformed tooth edges

582

PA6


AL

0965

584

PA6


AL

0966 Ghost line, molded

157

SAN


AL

0967 Giant (large) spherulites

501

PP

Injection molding Spherulite

DL-POL + 

0968 Giant (large) vacuole: due too-early end of the holding pressure

523

POM

Thin section

DL

0969

••in a fracture surface

531

PBTB


AL

0970

••through a lack of holding pressure 534

POM


DL-POL + 

PPS

Injection molding Measuring instrument

SEM

••gear rim and dividing error

0971 Glass balls (SEM subchapters): 0972

340–341

••in PPS 341 (see also → reinforcing materials)

Bearing seat

SEM

0973 Glass fiber breakage:

Definition

0974

••strong (visible through contrast mixture)

115

PA6.6-GF30

Thin ground sample

Cover

DL-POL + DIC

0975

••through strong orientation

114

POM-GF30

Thin ground sample

Cover

DL-POL

0976

••with point-shaped matrix adhesion 336

PPO-GF35


SEM

0977 Glass fiber content: higher

532

PP-GF40


AL

0978

121

PBT


AL

0979 Glass fiber core with bark-like displacement through H2SO4

335

UP

Filament winding

SEM

0980 Glass fiber diameter

339

FEP


SEM

0981 Glass fiber enhancement and glass fiber

116

PC-GF35

Thin ground sample

Molded part

DL-POL

0982 Glass fiber fabric with crack in the boundary area

566

PF-GF-Cu

Polished sample

Clutch lining

AL

0983 Glass fiber influence

521

PA6.6-GF25

Fracture surface

Housing

AL

28

••supports microvacuoles

Acid container


No.

Technical Term


Molded Part

Contrast

339

FEP


SEM

0985 Glass fiber length, average: in the defective part

112

PA6.6


DL

0986

111

PA6.6


DL DL-POL + DIC

••in the good part

0987 Glass fiber length distribution

Definition

0988 Glass fiber orientation

115

PA6.6-GF30

Thin ground sample

0989 Glass fiber parallel position

28

ABS


0990 Glass fiber reinforcement

331

PC-GF25

Injection molding Pressure vessel SEM

0991 Glass fiber segregation

116

PC-GF35

Thin ground sample

0992 Glass fiber strands, distribution

565

PF-GF-Cu


AL

0993 Glass fibers (LM subchapter, see also → reinforcing materials)

111–122

0994 Glass fibers (SEM subchapter)

331–339

SEM

0995 Glass fibers: are poorly integrated

213

PA6-GF30/PE

Adhesive tape method

AL

Cover

Molded part

Chair

AL DL-POL

0996

••exposed in the vacuole

535

PPS-GFM

Part

Pipe sleeve

AL

0997

••highly oriented

114

POM-GF30

Thin ground sample

Cover

DL-POL

Rope pulley

0998

••hinder the holding pressure

113

PA-GF25

Polished sample

0999

••protrude through the surface

122

PC


AL

1000

••protrude through the surface

338

PA-GF20


SEM

1001

••ripped out

341

PPS

Injection molding Measuring instrument

SEM

1002

••visible on the surface

254

PA6-GF30


AL: 1 : 1

PE


DL-POL

ABS/PC


AL

1003 Glass slide

Definition

1004 Glass temperature

Definition

1005 Glass transition

Definition

1006 Glass transition temperature range (glass temperature)

Definition

1007 Globule(s):

Definition

1008

086

••globule in a multilayer film

1009 Gloss measurement

Definition

1010 Gloss reflection simulates metal

125

1011 Gold plating, sputtering:

Definition

1012

Multilayer film

AL

371

PUR

Foaming

Foam

SEM

1013 Gold sputtering: of ABS

209

ABS

Vaporizing

Molded part

AL-DIC + 

1014

••of SB

210

SB

Vaporizing

Molded part

AL-DIC + 

1015 Good part, visible

282

POM-GF30

Injection molding Electrical switch AL

1016 Goose bumps (see → orange skin)

Definition

1017 GPC analysis

Definition

1018 Grain boundaries

507

POM

Thin section

1019 Graining

Definition

••of PUR

Spherulite

DL-POL + 

29

Glossary

0984 Glass fiber length


Glossary

No.

Technical Term


1020 Graining, unintentional

350

1021 Granulate (LM subchapter)

123–136

PC

Molded Part


Contrast SEM

1022 Granulate: inclusions

133

TEEE

Extrusion

Vacuum line

AL

1023

126

PE

Extrusion

Pipe

DL

••residue, unmelted

1024

••unmelted

Definition

1025

••unmelted, creates crowning

124

PP


AL

1026

••unmelted, for PA

135

PA


DL-POL + 

1027

••unmelted, for PP

124

PP

Polished sample

AL

ABS

Injection molding Thermos bottle

1028 Granulate contamination:

Definition

1029

132

••for ABS

Container

AL

1030

••for PC on vacuoles

518

PC

Extrusion

Granulate

AL

1031

••for HDPE after embedding

078

HDPE

Imbedding

Granulate

AL

1032

••for TEEE

133

TEEE

Extrusion

Vacuum line

AL

Sealing plug

1033 Granulate, residual: in new products

130

PE

Polished sample

1034

••unmelted

131

CA


AL

1035

••unmelted, varicolored

129

PA6.6

Polished sample

AL

328

PTFE


SEM

AL-DIC

1036 Graphite and carbon particles

Connector

AL

1037 Gravimetry (determination of weight) Definition 1038 Gray streaks

Definition

1039 Greenough principle (in the stereomicroscope)

Definition

1040 Grinding:

Definition

1041

079

PVC/Acryl

Polished sample

1042 Grinding marks

377

PEEK


1043 Groove

Definition

••instead of cutting (polishing)

Window profile

SEM

1044

••through mechanical load

377

PEEK


SEM

1045

••through scraping

545

PE100

Extrusion

Gas pipe

AL

1046

••with beaded edges

562

PE

Extrusion

Gas pipe

AL

1047 Growth direction of spherulites

509

POM

Thin section

Molded part

DL-POL + 

1048 Guide pins

Definition

1049 Guiding layer application (palladium)

266

ABS

Electroplating

Cover

AL

1050 Hair cracks: after weathering

016

PC


DL-DIC

1051

••after weathering

017

PC


DL

1052

••transitional area

018

PC


DL

1053 Hairline crack in PBT, brittle refracted

560

PBT

Injection molding Wind screen wiper

AL

1054 Halogen light source

Definition

1055 Haptics

Definition

1056 Hatch optical path

Definition

1057 Heat exposure:

Definition

1058

••at 60 °C

059

ABS


AL

1059

••at 90 °C

398

SAN


AL

1060

••at 150 °C

040

PVC-U + PMMA Thin section

30

Window profile

DL


No.

Technical Term

Molded Part

Contrast

••at 150 °C created cracks

403

C-PVC

Extrusion

Water pipe

AL

1062

••at 285 °C

428

PA-GF35

Injection molding Glass holder

AL

1063

••in a convection oven

570

ABS


AL: 1 : 1

1064

••of PMMA/PVC

169

PMMA/PVC

Thin section

Window profile

DL-DIC

PVC-U

Extrusion

Window profile

AL

1065 Heat stabilizers

Definition

1066 Heat treatment 230 °C with a hot air gun

009

Glossary


1061

1067 Heating element weld line:

074

PE

Extrusion

Blown film

DL-POL

1068

••cracked

471

PP

Heating element welding

Filter

AL

1069

••cracked

462

PP


Membrane

AL

1070

••fragile

477

PVC

Thin section

Window

AL

1071

••good

463

PP

Polished sample

Membrane

AL

1072

••good

483

PE


Hot plate weld line

AL

1073

••unfavorable

480

PE100


Weld line

AL

1074

••with air inclusion

461

PB


Mushroom valve

DL

1075

••with high fracture sensitivity

469

PE


Sheet

DL

1076

••with shear zones

470

PP100


Water pipe

DL-POL + 

1077

••with spherulites

502

PP

Thin section

Water pipe

DL-POL + 

1078 Heating element weld thickness

085

PE

Coextrusion

Carrying bag

AL

1079 Hold pressure

Definition

1080 Holding pressure:

Definition

1081

••dropped too soon

031

POM


AL

1082


301

POM

Thin section

DL-POL + 

Catch

1083


522

AMMA

Thin section

Holder

DL

1084


528

POM

Thin section

Torsion bar

DL-POL

1085


532

PP-GF40


DL

1086

••high

147

ABS


AL

1087

••ineffective

076

PA/PTFE

Thin section

Piston ring

AL

1088

••lowering towards the end

587

PC

Injection molding Cellphone housing

AL

1089

••path-dependent

534

POM


DL-POL + 

1090

••too low

507

POM

Thin section

DL-POL + 

Spherulite

1091

••too low

122

PC


AL

1092

••too short

152

POM


AL

PP

Thin section

DL-POL

1093 Holding pressure error

Definition

1094 Holding pressure stream

055

1095 Holding pressure time:

Definition

Filter

31


No.

Glossary

1096

Technical Term ••too short


Molded Part

Contrast

CP


AL

PA


SEM

DL-POL + 

1097 Hollow body, closed

Definition

1098 Hollow glass balls increase the dimensional stability

340

1099 Homogenization:

Definition

1100

••poor, for PA

101

PA

Thin section

Molding compound

1101

••poor, for PA

499

PA

Imbedding

Electric conduit DL-POL + 

1102

••poor, for PA

504

PA

Thin section

Molded part Molded part

DL-POL + 

1103

••poor, for PA6.6

505

PA6.6

Thin section

1104

••poor, for PC

017

PC


DL

1105

••poor, for PE

128

PE

Thin section

DL

Sheet

DL-POL + 

1106

••poor, for PE

287

PE

Thin section

Roof sheeting

DL

1107

••poor, for PE80

044

PE80

Extrusion

Pipe

AL

1108

••poor, for POM

523

POM

Thin section

Bearing seat

DL

Container

1109

••poor, for PP

124

PP

Polished sample

1110

••poor, for PP

425

PP


AL

1111

••poor, for PP-GF30?

038

PP-GF30

Polished sample

Light well

AL

1112

••poor, for PE?

294

PE

Extrusion

Water pipe

DL

SAN


AL AL

1113 Homogenization error

Definition

1114 Homogenization, poor

Definition

1115 Homogenization time too short

156

1116 Hot air treatment:

Definition

1117

••resolves welding stresses

480

PE100

Block ground sample

1118

••with a hot-air gun

149

SB


Weld line

AL

AL

1119

••with gas flame

487

PE100

Flaming

Gas pipe

AL

1120

••with welding dryer resolves welding stresses

480

PE100

Block ground sample

Weld line

AL

PA

Thin section

Molded part

DL-POL + 

PA11


DL-POL + 

PS


DL + AL

1121 Hot-cold mixture:

Definition

1122

504

••in PA

1123 Hot-cold streaks:

Definition

1124

460

••in PA11

1125 Hot mounting

Definition

1126 Hot runner

144

1127 HPLC analysis

Definition

1128 Hydrolysis:

Definition

1129

415

POM


AL

1130 Identification through color pigments 351

PVDF


SEM

••of POM

1131 Illumination

Definition

1132 Illumination with oblique incident light:

191

PC


AL

1133

272

ABS/PC

Electroplating

AL, diagonal

32

••for ABS/PC

Bushing


No.

Technical Term

Molded Part

Contrast

••for PA6-GF30/PE

213

PA6-GF30/PE

Coated surface

Chair

AL

1135

••for PP

286

PP


AL-DF

1136

••for PVC

292

PVC

Extrusion

Water pipe

AL

1137

••for SB

273

SB

Electroplating

Housing

AL

1138 Image resolution

Definition

1139 Immersion optics

Definition

1140 Impact assessment:

Definition

1141

••for PBTP-GF20

240

PBTP GF20

Injection molding Power window actuator

AL

1142

••for SB

241

SB


AL-DF

1143 Implant (SEM subchapter)

342–349

SEM

1144 Implant filament

326

Vicryl

Spinning

Suture material

SEM

1145 Implant pin, self-dispersing: see Figs. 342–349

342

PLA98

Medical comparison

Implant pin

SEM

1146 Incineration

Definition

1147 Incipient crack:

Definition Water pipe

1148

••in crack flanks

043

PVC

Extrusion

1149

••in PVC

392

PVC


AL

391

PPE


AL

1150 Incipient crack area: in PPE

Glossary


1134

AL

1151

••in SB

312

SB


SEM

1152

••in the failure area

526

PPE

Injection molding Fastener clamp

AL

1153

••including contaminating particles

281

PVC-U

Extrusion

Pipe

AL-DF

1154 Increase in contrast through contrast blending:

115

PA6.6-GF30

Thin ground sample

Cover

DL-POL + DIC

1155

••through combined contrast processes

427

PVC-U

Thin section

Window profile

DL/POL/ /DIC

1156

••with an aperture diaphragm

114

POM-GF30

Thin ground sample

Cover

DL-POL

1157

••with fuchsine

260

PA


AL

1158 Influence of gravity: during metallization

276

ABS

Electroplating

AL

1159

Molded recess

197

PA6

Injection molding Handle frame

AL

1160 Influence on the breaking strength

112

PA6.6


DL

1161 Influences on quality and costs

Definition

1162 Ingredients

Definition

1163 Inhibitor supplement, incompatible

245

PB

Extrusion

Heating pipe

AL

1164 Inhibitors

Definition

1165 Inhomogeneity(ies)

Definition

1166 Injecting:

Definition

1167

099

PC

Thin section

Tooth fracture

DL-POL + 

••during painting

••too fast

1168

••too fast

357

PBTP


SEM

1169

••too fast

459

PC


AL

1170

••turbulent

231

PB

Electroplating

DL-POL + 

1171 Injection molding

Molded part

Definition

33


Glossary

No.

Technical Term


1172 Injection molding error (injecting error)

Definition

1173 Injection molding of a core, asymmetrical

050

1174 Injection pressure

Definition

1175 Injection rate:

Definition

1176

449

••too high

1177 Injection, turbulent:

Molded Part

Contrast

PA6.3


AL: 1 : 1

PC


DL

Definition

1178

••for ASA

324

ASA


SEM

1179

••for PC

099

PC

Thin section

Tooth fracture

DL-POL + 

1180 Inliner: with cracks

255

PP-R/AL/PP-R

Polished sample

Composite pipe AL

1181

••with cracks

256

PP-R/AL/PP-R

Extrusion

Composite pipe AL

1182

••with cracks

259

PVC + EPDM

Extrusion

Tube

AL

1183 Insert:

Definition

1184

••generates tension in the molded part

490

SAN


DL

1185

••preheating, missing

386

ABS


AL

1186 Inserted part: brass nut

386

ABS


AL

1187

••metal shaft

490

SAN


DL

1188 Integral foam thickness

423

PVC-U

Foaming

Pipe

AL

1189 Integral foam with cracks

310

PUR foam

Foaming

Bumper

SEM

1190 Integral hinge with layer formation

433

PP

Injection molding Integral hinge

DL-POL

1191 Interference

Definition

1192 Interior cracks are made visible

191

PC


AL

AL

1193 Internal stresses:

Definition

1194

••and low degree of gelling

009

PVC-U

Extrusion

1195

••by macromolecule orientation

140

PE

Injection molding Spray nozzle

Window profile

DL-POL

1196

••high

065

PC

Vacuum forming

1197

••inside the sprue

488

ABS/PC

Injection molding Control button

AL

1198

••too high

151

HDPE


AL

1199 Internal stresses of the molded part (molded part stresses):

072

PBT

Thin section

DL

1200

••through core displacement

252

PP

Injection molding Protective cover

AL: 1 : 1

1201

••through solvent penetration in the paint

262

PA/PE

Thin section

DL

Skylight

Hub cap

AL

1202

••through temperature influence

570

ABS


AL: 1 : 1

1203

••through uneven tempering

568

PBT-T40

Injection molding Top cover

AL: 1 : 1

1204

••with bulging

569

PBT-T40

Injection molding Top cover

AL: 1 : 1

1205

••with warpage

571

ABS


AL: 1 : 1

PE/PA6/PP/ PE

Polishing trials

AL-DIC

1206 Inversion layer(s)

Definition

1207 IR analysis

Definition

1208 IR and DSC analysis

097

34

Packaging


No.

Technical Term

Figure No. Type of Plastic Processing 137–142

1210 Isochromatics:

Definition

Molded Part

Contrast

1211

••in a bad part

239

SAN

Comparison

Cup

DL-POL

1212

••in a good part

238

SAN


DL-POL

1213

••in PA

499

PA

Imbedding

DL-POL + 

1214

••in SAN

138

SAN


Electrical conduit

DL-POL

1215

••in SAN

139

SAN


DL-POL

1216

••in SAN

485

SAN


DL-POL

1217

••through internal stresses

077

PA

Thin section

Electrical conduit

DL-POL + 

PE

Extrusion

Cable conduit

AL

1218 Jacket heating:

Definition

1219

280

••too low

1220 Jam bushing

Definition

1221 Joint sealant: polysulfide 2C

026

Polysulfide 2C

Grouting

Joint sealant

AL: 1 : 1

1222

••PUR 1C

027

PUR 1C

Grouting

Joint sealant

AL: 1 : 1

1223 Kaolin, mineral filler

330

PA


SEM

1224 Knife angle for thin sections

Definition

1225 Köhler illumination (microscope optimization)

Definition

1226 Knives for thin sections

Definition

1227 L : D ratio too large:

035

PE

Extrusion

Sheet

AL

1228

453

PE

Extrusion

Sheet

DL

PA11


•• at the extrusion of PE

1229 Lack of holding pressure:

Definition

1230

573

••in a material accumulation

AL

1231

••partial

120

PBT


AL

1232

••partial

375

ASA


SEM

1233

••through a frozen sprue

525

POM


AL

1234

••through a missing residual mass cushion

524

PA6.6-GF30


AL

1235

••through cold molds

299

POM

Thin section

DL-POL + 

Housing

1236

••through glass fibers

533

PP-GF40


DL

1237

••with microvacuole

376

PPO

Molded part

SEM

1238

••with vacuoles

526

PPE

Injection molding Closing clamp

AL

PP

Thin section

DL-POL + 

1239 Lambda plate (-plate):

Definition

1240

186

••colors POL

1241 Laminating (LM subchapter)

169–171

1242 Laminating:

Definition

Molded part

PP sheet

1243

••of PVC-U with a decorative film

010


Window profile

AL

1244

••with a laminating film

169

PVC-U + PMMA Thin section

Window profile

DL

1245

••with an oxygen barrier layer

066

VPE/VA

Pipe

DL-DIC + 

Extrusion

1246 Laminating film: 50 µm with bubble

040


Window profile

DL

1247

171

PVC

Window profile

DL-DIC + 

••embossing foil

1248 Large and small spherulites:

Thin section

Definition

35

Glossary

1209 Isochromatics (LM subchapter)


No.

Glossary

1249

Technical Term ••PP-matrix

1250 Large vacuole


Contrast

PP


DL-POL

520

PBTP-GF20


AL

PC

Polished sample

AL + DL

1251 Laser error:

Definition

1252

218

••energy too high

Molded Part

426

Printer cover

1253

••gas and particle generation

220

POM

Thin section

Push button

DL

1254

••penetration depth too deep

218

PC

Lasering

Printer cover

AL + DL

1255

••point load

218

PC

Lasering

Printer cover

AL + DL

1256

••pulsation

220

POM

Thin section

Push button

DL

1257

••writing speed too fast

220

POM

Thin section

Push button

DL

220

POM

Thin section

Push button

DL

1258 Laser head suction 1259 Laser writing:

Definition

1260

••incorrect, through Nd YAG laser

214

PC

Lasering

Printer cover

AL: 1 : 1

1261

••with clear laser track

216

PC

Lasering

Printer cover

AL + DL

1262

••with cloudy structure

220

POM

Thin section

Push button

DL

1263

••with foaming bubble structure

219

POM

Thin section

Push button

DL

1264

••with repeated overwriting

215

PC

Lasering

Printer cover

AL + DL

1265

••with shell cracks

218

PC

Polished sample

Printer cover

AL + DL

1266

••with shell-like fracture areas

217

PC

Lasering

Printer cover

AL + DL

1267

••with uneven coloring

215

PC

Lasering

Printer cover

AL + DL

1268

••with weakly contrasting edge region

220

POM

Thin section

Push button

DL

1269 Lasering (LM subchapter)

214–220

1270 Lasering of letters and numbers

Definition

1271 Layer: construction (protective film)

169

PVC-U

Thin section

Window profile

DL-DIC

1272

••delamination

430

PC

Back injection

Car radio push button

AL

1273

••delamination through media

369

SBR


SEM

1274

••displacement

Definition

1275

••for a composite pipe

256

PP-R/AL/PP-R

Extrusion

Composite pipe AL

1276

••for a PVC-U lamination

171

PVC-U

Thin section

Window profile

1277

••fracture

318

PC

Injection molding Thermostat valve

SEM

1278

••site of fracture (Multilayer film)

089

PE


Multilayer film

DL-POL

1279

••thickness

Definition PS

Thin section

Cover

DL

1280 Layer flows, multilayered

102

DL-DIC + 

1281 Layer formation:

Definition

1282

••through mass flows in PA6

100

PA6

Thin section

Handle

DL-POL + 

1283

••through mass flows in PS

102

PS

Thin section

Cover

DL

1285 Leakage current mark: after electrical 080 breakdown

PP

Compression molding

Membrane

AL

1286

POM-GF30

Injection molding Electrical switch AL

1284 Layers (LM subchapter)

36

••through metal particles

421–444

282


No.

Technical Term

296

1288 Lens barrel

Definition

1289 Level of gelling:

Definition

1290

009

••60 to 70%

1291 Light field diaphragm:

Definition

1292

104

••see Figs. 104–107

1293 Light microscope LM

Definition

1294 Light, polarized

Definition

1295 Light stabilizers

Definition

1296 Light transmittance, decreasing

023

1297 Line marking: braid pattern-like on PE 379

Molded Part

Contrast

SI

Casting


AL

PVC-U

Extrusion

Window profile

AL

—

Microscope

PVC


Roof section

DL

PE

Extrusion

Pipe

SEM

Pipe

Glossary


1287 Leaking through fungi

AL: 1 : 1

1298

••hole or amorphous particle?

126

PE

Extrusion

1299

••on PA6.6

381

PA6.6


SEM

1300

••on SB through slip stick scratch

380

SB


SEM AL-DIC + 

DL

1301 Link chain

Definition

1302 Lint under yellow top coat

209

ABS

Vapor deposition

Molded part

1303 Lip crack: in a composite pipe

020

PE-RT/AL/ PE-RT

Extrusion

Composite pipe AL

1304

••in a heating pipe

412

PB

Extrusion

Heating pipe

AL: 1 : 1

1305

••typical

390

PB

Extrusion

Heating pipe

AL

1306 LM

Definition

1307 LM figure numbers in the book, all

001–323 and 381–588

1308 Longitudinal orientation of the macromolecules

137

PE


Bottle

DL-POL

1309 Longitudinal risk of cracking

137

PE


Bottle

DL-POL

1310 Longitudinal direction can withstand twice the tension of the transverse direction

390

PB

Extrusion

Heating pipe

AL

1311 Long-term cracks, flexing

242

POM

Injection molding Heavy duty castor, POM

AL

1312 Long-term internal pressure test

404

PE63

Extrusion

Water pipe

AL

1313 Long-term lines

306

POM

Thin section

Torsion bar

DL-POL + 

1314 Lubricant (internal and external)

Definition

1315 Macro- and microscopic examination Definition 1316 Macromolecule bonding, physical

195

TPE

Injection molding Spring element

1317 Macromolecule orientation:

140

PE

Injection molding Spraying nozzle DL-POL

1318

••in SAN

142

SAN


DL-POL

1319

••in SAN

485

SAN


DL-POL

1320 Macromolecules

Definition

1321 Macroscope

Definition

AL: 1 : 1

37


Glossary

No.

Technical Term


1322 Magnesium oxide particle

363

1323 Magnification

Definition

1324 Magnification number

Definition

1325 Magnification, optimal

Definition

Molded Part

Contrast

Fluorelastomer Injection molding Fluor elastomer SEM

1326 Main inspection, microscopic

Definition

1327 Main valence forces

Definition

1328 Mandrel crack: gaping

519

PBTP-GF20


AL

1329

AL

417

PC-CF10

Polished sample

1330 Mandrel fracture: by reduced flowability

575

PP-GF40


AL

1331

152

POM


AL

1332 Mandrel half with cracks

394

POM


AL

1333 Manufacture too cold

061

PA6.6

Injection molding Hinge

AL

1334 Marginal zone (LM subchapter)

299–306

••in bolted mandrel

••with cold flow lines close to the fracture

Housing

1335 Marginal zone of amorphous plastics Definition 1336 Marginal zone: extremely poor in spherulites

508

POM

Thin section

Clutch

DL-POL + 

1337

••extremely poor in spherulites (1300 µm)

529

POM

Thin section

Torsion bar

DL-POL

1338

••for amorphous plastics

304

CP

Injection molding Threaded nut

AL

1339

••hardly visible

534

POM

Thin section

Bolt

DL-POL + 

1340

••hardly visible poor in spherulites

303

PA

Thin section

Part

DL-POL + 

1341

••is missing for extreme cold temperatures

503

PA6

Thin section

Spherulite

DL-POL + 

1342

••poor in spherulites

Definition

1343

••poor in spherulites

527

POM

Injection molding Pipe bracket

AL

1344

••poor in spherulites (frozen pinpoint gate)

076

PA/PTFE

Thin section

Piston ring

AL

1345

••poor in spherulites, with embrittlement

302

POM

Thin section

Acme thread

DL-POL + 

1346

••poor in spherulites, with transition without rounding

305

POM

Thin section

Torsion bar

DL-POL + 

1347

••semicrystalline plastics

Definition

1348

••strongly poor in spherulites

299

POM


DL-POL + 

1349

••strongly poor in spherulites, mainly amorphous

300

POM

Thin section

DL-POL + 

1350

••unequal

533

POM

Injection molding Bracket

DL-POL

1351

••unequally poor in spherulites

301

POM

Thin section

DL-POL + 

1352 Mass accumulation:

Housing

Snap fit

Definition

1353

••in PA11

530

PA11

Specimen

Water filter

AL

1354

••in PA6-GF15

181

PA6-GF15

Polished sample

Clamping mechanism

AL

1355

••in PBTB

531

PBTB


AL

1356

••in POM

534

POM

Injection molding Bolt

DL-POL + 

38


No.

Technical Term


1358

••leading

Definition

1359

••longitudinally and transversely in PE

137

Molded Part

Contrast

POM


AL

PE


Bottle

DL-POL

Sheet

1360

••many, in PE

035

PE

Extrusion

1361

••three (M1, M2 und M3)

159

PA4.11


AL: 1 : 1

1362

••three, in CA

029

CA


AL

Glossary

1357 Mass flows: highly viscous (cold), in POM

AL

1363

••three, in PA4.11

160

PA4.11


DL-POL

1364

••two, in ABS

028

ABS


AL

1365

••two, in SB

030

SB


AL

1366

••two, leading in PP

252

PP


1367 Mass inversion (LM subchapter)

099–102

1368 Mass inversion (with and without induction):

Definition

1369

••through turbulent mold filling

102

PS

Thin section

1370

••with hot-cold streaks

101

PA

Injection molding Molding compound

DL-POL + 

1371

••with large and small spherulites

099

PC

Injection molding Saw tooth fracture

DL-POL + 

1372

••with spherulite streaks

100

PA6

Thin section

Handle

DL-POL + 

Cover

DL

1373 Mass stream, free

Definition

1374 Mass swivel (LM subchapter):

231–232

1375

••creates a loss of strength

232

PC

Electroplating

Part

DL-POL + 

1376

••with air induction, reason for electroplating errors

231

PA

Thin section

Part

DL-POL + 

1377 Mass temperature:

Definition

1378

135

PA


DL-POL + 

1379 Mass volume and shrinkage

536

PC

Part

AL

1380 Masterbatch:

Definition

••too low

Part

1381

••subsequent, in ABS

446

ABS

Thin section

Siphon

DL

1382

••subsequent, in PE

071

PE

Preparation

Water pipe

DL

1383

••subsequent, in PE

128

PE

Extrusion

Sheet

DL

1384

••subsequent, in PE-X

454

PE-X

Extrusion

Pipe

DL

1385

••subsequent, in POM

523

POM

Thin section

Bearing seat

DL

1386 Masterbatch carrier, unsuitable

Definition

1387 Masterbatch change (rebatching)

Definition

1388

••from PVC

540

PVC

Bubble packaging Conveyor belt

DL-POL

1389

••PA-PTFE

541

PA/PTFE

Injection molding Compression ring

AL

1390

••PA-PTFE

542

PA/PTFE

Injection molding Compression ring

AL

1391 Masterbatch mix-up

293

PE

Extrusion

Water pipe

DL

1392 Material failure

500

HDPE

Extrusion

Water pipe

AL

1393 Material residue transfer:

Definition

39


No.

Glossary

1394

Technical Term ••in PPS

1395 Matrix:


Molded Part

Contrast

PPS


AL

PC-GF30


SEM

Definition

1396

••a few residues, on the glass fibers 334

1397

••degradation

Definition

1398

••materials for WPC

196

WPC

Extrusion

1399

••residue on the glass fibers

333

PC-GF30


SEM

1400

••strongly attacked

026

Polysulfide 2C

Jointing

AL: 1 : 1

Profile Joint sealant

AL: 1 : 1

1401

••very slightly attacked

027

PUR 1C

Grouting

Joint sealant

AL: 1 : 1

1402

••weakening

035

PE

Extrusion

Sheet

AL

1403

••welding, poor

123

PETP

Thin section

Housing

DL-POL + 

1404

••with red-brownish particles

542

PA/PTFE


PC-GF25


1405 Matrix bonding (adhesion):

Definition

1406

331

••1. poor

AL

1407

••2. a little better

332

UP-GF

Laminating

1408

••3. very good

333

PC-GF30


SEM

1409

••poor

213

PA6-GF30/PE

Coating

AL

Housing Chair

SEM

1410

••poor

312

SB


SEM

1411

••partially good

337

PVC-GF15


SEM

1412

••point-like

336

PPO-GF35


SEM

1413

••reduced

425

PP


AL

1414

••reducing through pigments

351

PVDF


SEM

1415

••very poor

334

PC-GF30


SEM

PVC + EPDM

Extrusion

Composite pipe AL

PVC + EPDM

Extrusion

Reinforced hose

AL

PA6


AL AL: 1 : 1

1416 Matte spots

Definition

1417 Measure copper content Cu

259

1418 Measure residues

Definition

1419 Measure verdigris with an atomic absorption

259

1420 Measuring plate

Definition

1421 Mechanical deformation

582

1422 Media (LM subchapter)

233–262

1423 Media:

253

PA6-GF30


1424

••double refraction

186

PP

Thin section

Sheet, PP

DL-POL + 

1425

••examine the influence before application

498

PC

Turning


DL

1426

••which can cause tension cracking

Rotational molding

Surface

SEM

1427 Media attack (SEM subchapter)

Definition 358–360

1428 Media attack:

Definition

1429

359

••check beforehand if possible

SEM PP

1430

••circular

235

PP

Extrusion

Water pipe

AL

1431

••drop-like

562

PE

Extrusion

Gas pipe

AL

1432

••drop-shaped

017

PC


DL

1433

••for PA11

530

PA11

Specimen

Water filter

AL

1434

••for PA6.6-GF30

117

PA6.6-GF30

Thin section

Handle

DL

40


No.

Technical Term

Molded Part

Contrast

••for PMMA

384

PMMA

Vacuum forming

Light well

DL

1436

••strong

246

POM

Compression molding

Lid

AL: 1 : 1

1437

••through chemicals or UV

131

CA


AL

1438

••through copper

248

PP-R

Extrusion

Fitting

AL

1439

••through formic acid

246

POM

Compression molding

Lid

AL: 1 : 1

1440

••through incompatible inhibitor additive

245

PB

Extrusion

Heating pipe

AL

1441

••through local medium

233

PUR

Extrusion

Air hose

AL

1442

••through new, untested cleaning agents

360

PMMA


SEM

AL: 1 : 1

Glossary


1435

1443 Media cracks:

Definition

1444

••inside the thread through cooling emulsion

237

PC

Turning

1445

••in SBR

369

SBR


SEM

1446

••net-like

234

SB

Vacuum forming

Cleaning tray

AL

1447 Media halos due to cutting oil

249

PVC

Extrusion

Shutter

AL: 1 : 1

1448 Media influence

Definition

1449 Media streaks

Definition

1450 Medium penetration depth complies with delamination

369

SBR


SEM

1451 Medium spot with elevated edge

247

CA


AL

1452 Melt fracture: during blow molding

048

PP


Bottle

AL

1453

089

PE


Multilayer film

DL-POL

1454 Melt table, microscope

501

PP

Thin section

Spherulite

DL-POL + 

1455 Melting temperature range

Definition

1456 Metal abrasion (LM subchapter)

263–264

1457 Metal abrasion:

Definition ABS/PC


AL

1458

••in a multilayer film

••suspected, but is a gloss reflection 125

Glass holder

1459 Metal analysis

Definition

1460 Metal or plastic particle?:

263

PP

Pinpoint gate

Pinpoint gate

AL

1461

264

PP

Pinpoint gate

Pinpoint gate

AL

POM-GF30

Injection molding Electrical switch

AL

••in PP

1462 Metal particles:

Definition

1463

282

••in the surface

1464 Metallizing (LM subchapter)

265–278

1465 Metallizing (see also → electroplating)

Definition

1466 MFR analysis (MFR value):

Definition

1467

463

PP

Polished sample

Membrane

AL

1468 Micelle growth

298

HDPE

Extrusion

Water pipe

AL

1469 Microcrack region (craze)

370

PE


••deviating

SEM

41


Glossary

No.


Molded Part

Contrast

1470 Microcracks: 500-µm deep

Technical Term

015

ECB

Extrusion

Roof sheeting

AL

1471

017

PC


DL

••after 2-years outdoor weathering 2

1472

••after 8000-MJ/m artificial weathering

013

EPDM

Extrusion

Sealing profile

AL

1473

••are preparation errors

102

PS

Thin section

Cover

DL

1474

••insular

007

PA/PTFE


AL: 1 : 1

1475

••intercrystalline

507

POM

Thin section

Spherulite

DL-POL + 

1476

••on PVC film

361

PVC

Calendering

Film

SEM

1477

••through wetting agent test


DL-POL

485

SAN

1478 Microbes (SEM subchapter)

361–362

SEM

1479 Microbiological growth: on a PE film

362

PE


Film

SEM

1480 Microscope (light microscope)

Definition

1481 Microscope optimization

Definition

1482 Microscope parts

Definition

1483 Microscopic examination

Definition

1484 Microscopy accompanying research and work

Definition

1485 Microscopy contrast with the wrong DIC slider

066

VPE/VA

Extrusion

Pipe

DL-DIC + 

1486 Microscopy with oblique incident light 561

PBT/PC

Block section

Housing

AL-DF

1487 Microtome (thin-section equipment)

110

—

Microtome

—

—

1488 Microvacuole(s):

Definition

1489

••in a close up

375

ASA

1490

••in a mandrel

520

PBTP-GF20


AL

1491


468

ASA

Polished sample

AL

1492

••in PPO

376

PPO

1493


532

PP-GF40

Housing Housing Molded part Injection molding Rope drum

SEM

SEM DL

1494

••numerous, weaken cross-section

113

PA-GF25

Polished sample

Rope pulley

AL

1495

••tension cracking, contribute to

181

PA6-GF15

Polished sample

Clamping mechanism

AL

1496

••through high glass-fiber content

121

PBT


1497 Migration:

Definition

1498

Definition

••measure

AL

1499

••of pigments

117

PA6.6-GF30

Thin section

Handle

DL

1500

••with strong swelling

244

C-PVC

Extrusion

Water pipe

AL: 1 : 1

1501 Mixing spherulite: in PA

101

PA


DL-POL + 

1502

100

PA6

Thin section

Handle

DL-POL + 

128

PE

Thin section

Sheet

DL

Pipe

••in PA6

1503 Mix-up with: a foreign particle 1504

••carbon black conglomerate

126

PE

Extrusion

1505

••metal abrasion

125

ABS/PC


AL

1506 Moisture absorption

117

PA6.6-GF30

Thin section

DL

1507 Moisture in the molding compound

Definition

42

Handle

DL


No.

Technical Term


1509 Mold (LM subchapter):

574–588

Molded Part

Contrast

1510

••cold

029

CA


AL

1511

••cold

030

SB


AL

1512

••too cold

509

POM

Thin section

DL-POL + 

1513 Mold aging

513

PA6-GF30

Injection molding Armrest

AL

1514 Mold breathing:

Definition

1515

514

PE


AL

1516 Mold bushing, worn

165

PCTFE


AL

1517 Mold changes: subsequent, for PA6-GF30

513

PA6-GF30


AL

1518

182

PC


AL

••when injection molding

••subsequent, for PC

Part

1519 Mold clamping

Definition

1520 Mold closing force

Definition

1521 Mold filling, poor:

Definition

1522

••for ABS

585

ABS


AL

1523

••for PC

574

PC


AL

1524

••for PE

145

PE


AL

1525

••for POM

580

POM


AL

1526

••for PPS

577

PPS


AL

1527

••oscillating, for PA

504

PA

Thin section

Part

DL-POL +  DL-POL + 

1528

••oscillating, for PA6

100

PA6

Thin section

Handle

1529

••swirled, for PB

231

PB

Electroplating

Part

1530

••too slow, for ASA

161

ASA


AL

1531

••turbulent, for PC

232

PC

Electroplating

Part

DL-POL + 

1532

••turbulent, for PS

Cover

DL-POL + 

102

PS

Thin section

1533 Mold guidance, worn

049

PA6.3


AL: 1 : 1

1534 Mold halves: equally heated

534

POM


DL-POL + 

1535

••unequally heated

301

POM

Thin section

DL-POL + 

1536

••unequally heated

533

POM


DL-POL

POM


AL

1537 Mold impression:

Definition

1538

146

••bad

Snap fit

DL

1539

••poor

515

ABS

Injection molding Siphon

AL

1540

••poor

576

ABS/PC


AL

1541

••poor

578

PPS


AL

1542

••very cold

166

PE


AL

1543 Mold impression, rough

513

PA6-GF30


AL

1544 Mold marking

033

POM


AL

1545 Mold offset

Definition

1546 Mold overfilling

Definition

1547 Mold remolding too early: for PE

053

PE

Injection molding Sealing cap

AL

43

Glossary

1508 Moisture streaks


No.

Glossary

1548

Technical Term ••for POM

1549 Mold resistance

Figure No. Type of Plastic Processing 058 Definition

1551

084

1552 Mold synchronization

Definition

1553 Mold tempering, unequal

301

1554 Mold temperature:

Definition

1555

299

••cold, for POM

Contrast


AL

PE

Extrusion

Corrugated pipe

AL

POM

Thin section

Snap fit

DL-POL + 

POM

Thin section

Housing

DL-POL + 

Definition

1550 Mold separation: ••shear joint in the mold separation

Molded Part

POM

1556

••extremely low, for PE

319

PE


SEM

1557

••too cold, for ABS

147

ABS


AL

1558

••too cold, for ABS

515

ABS


AL

1559

••too cold, for ASA

161

ASA


AL

1560

••too cold, for PA-GF20

338

PA-GF20


SEM

1561

••too cold, for PC

122

PC


AL

1562

••too cold, for POM

146

POM


AL

1563


152

POM

Injection molding Carrier

AL

1564


525

POM


AL

1565

••too cold, for PP

001

PP

Injection molding Protective cover AL

1566

••too cold, for PP-GF40?

575

PP-GF40


AL

1567 Mold temperature influence

503

PA6

Thin section

DL-POL + 

1568 Mold venting:

Definition

Spherulite

1569

••bad

457

PC


1570

••poor

231

PB

Electroplating

1571

••unsatisfactory

448

SAN


1572 Mold venting error

459

PC


AL

1573 Mold wetting, poor, for: ABS/PC

579

ABS/PC


AL

1574

581

ABS/PC

Injection molding Molded recess

AL

••ABS/PC

Part

AL DL-POL +  DL

1575

••PA6-GF30/PE

213

PA6-GF30/PE

Coating

1576

••PE

145

PE


AL

1577

••POM

031

POM


AL

Armrest

AL

1578

••PP-GF40

575

PP-GF40


AL

1579

••PS

155

PS


AL

1580 Molded part cracks create paint cracks

208

ASA

Thin section

DL-POL + 

1581 Molded part deflection (core deflection)

049

PA6.3


AL: 1 : 1

1582 Molded part edge, burnt

538

PA6-GF30


AL

1583 Molded part embrittlement

Definition

1584 Molded part error

Definition

1585 Molded part impression

Definition

1586 Molded part optimization

Definition

1587 Molded part quality:

Definition

44

Housing


No. 1588

Technical Term


PC

Molded Part

Injection molding Phone housing

Contrast AL

1589

••improving

586

PC

Injection molding Phone housing

AL

1590

••poor, with ABS

585

ABS

Injection molding Blind

AL

1591

••poor, with PA6-GF30

513

PA6-GF30


AL

1592

••poor, with PE

166

PE


AL

1593

••poor, with POM

004

POM


AL

1594 Molded part quality when extruding or injecting

Definition

1595 Molded part seam

Definition

1596 Molded part shrinkage: for CP

572

CP


AL

1597

573

PA11


AL

PC-GF35

Thin ground sample

Part

DL-POL

1601 Molded part surface: is broken down 048

PP


Bottle

AL

1602

PA6-GF30/PE

Tape method

Chair

AL

Chair

••for PA11

1598 Molded part strength

Definition

1599 Molded part strength, reduced

116

1600 Molded part stresses

Definition

••is defective

213

1603

••is incorrectly painted

212

PA6-GF30/PE

Tape method

1604

••is open

578

PPS


AL

1605

••is rough and bubble-like

036

PP-GF30


AL

1606

••tortured

153

ABS/PC


AL

AL

1607 Molded parts

Definition

1608 Molding compound: distant from the gate and inhomogeneous

034

POM


AL

1609

••burnt

290

PB

Extrusion

DL

1610

••cold

Definition

1611

••cold, entrained

150

ABS


AL

1612

••cold, for ABS

147

ABS


AL

1613

••cold, for PE

379

PE

Extrusion

SEM

1614

••cold, for POM

031

POM


AL

SB


AL

AMMA

Thin section

DL

1615

••cold, for SB

030

1616

••flow behavior

Definition

1617

••inhomogeneous, for AMMA

522

Pipe

Pipe

Bracket

1618

••inhomogeneous, for PE

130

PE

Polished sample

Sealing plug

AL

1619

••not colored, for PE

294

PE

Extrusion

Water pipe

DL

1620

••previously colored

Definition PE

Thin section

Sheet

DL

PC


AL-DF

ABS/PC


AL

1621

••previously colored, for PE

128

1622

••reinforced

Definition

1623

••too cool, for PC

154

1624

••too cold at the end of the flow path 579

Glossary

••accurate, with high initial holding pressure

45


Glossary

No.


Molded Part

Contrast

1625

Technical Term ••too cold, for POM

509

POM

Thin section

Part

DL-POL + 

1626

••too cold, for PS

155

PS


AL

1627

••too tough (viscous)

574

PC


AL

1628

••with a too-low mold temperature

395

PPSU


AL

1629 Molding compound flow, reduced:

Definition

1630

••reduced

166

PE


AL

1631

••tough

521

PA6.6-GF25

Fracture surface

AL

1632 Molding compound particles

512

LDPE

Injection molding Rope holder

AL

1633 Molding compound residue transfer:

Definition

1634

••residue transfer?

036

PP-GF30


AL

1635

••visible on the surface

Housing

512

LDPE


AL

1636 Molding compound stream:

137

PE

Blow molding

DL-POL

1637

140

PE


••mass flows

1638 Molding compound temperature

Definition

1639 Molding compound temperature, too-cold:

Definition

Bottle

DL-POL

1640

••for ASA

161

ASA


AL

1641

••for PA6.6

063

PA6.6


AL

1642

••for PE

082

PE

Blow molding

Diesel container AL

1643

••for PE

084

PE

Extrusion

Corrugated pipe AL

1644

••for PE

128

PE

Thin section

Sheet

DL

1645

••for POM

146

POM


AL

1646

••for PP

124

PP

Polished sample

AL

1647

••for SAN

156

SAN


1648

••too cold?

Container

AL

575

PP-GF40


AL

1649 Mold-post processing?

157

SAN


AL

1650 Monomer

Definition

1651 Mouth and respiratory flora through eating habits

296

SI

Casting


AL

1652 Moving in the seam, V-shaped

082

PE


Diesel can

AL

1653 Multifocus

Definition

1654 Multifocus recordings

Definition

1655 Multiple coating application, accidental

204

ABS


AL

1656 Multiple-layer film: 6 film and 5 adhesive layers

098

—


Coating layer

DL-POL + AL

1657

••7 layers

097

PE/PA6/PP/ PE

Polishing

Packaging

AL-DIC

1658

••burn streaks (3 layers)

091

PE


Multilayer film

DL-POL

1659

••film warp

094

PE


Multilayer film

DL-POL

46


No.

Technical Term

Molded Part

Contrast

••globule

086

PE


Multilayer film

DL-POL

1661

••globule

087

PE


Multilayer film

DL-POL

1662

••hole (3 layers)

088

PE


Multilayer film

DL-POL

1663

••layer fracture

089

PE


Multilayer film

DL-POL

1664

••melt fracture (3 layers)

090

PE


Multilayer film

DL-POL

1665 Multi-shearing, flow layers with shearing

460

PA11

Thin section

Part

DL-POL + 

1666 MVR analysis (MVR value)

Definition

1667 Nanocomposites

Definition

1668 Nanofillers

Definition

Glossary


1660

1669 Needle shut-off nozzle:

Definition

1670

••leaking, replace

284

PS


DL-POL + 

1671

••mark

383

PB

Injection molding Lid gate

AL

1672

••with film residues

283

PS


AL

1673 Needle stick, intentionally

378

PVC

Extrusion

Surface

SEM

1674 Neofluar lenses

Definition

1675 Nondestructive testing

172

PVC

Adhesion

Bonded socket joint

AL: 1 : 1

1676 Normal stress center:

Definition

1677

••in a fracture center

321

SB


SEM

1678

••in PB

316

PB

Extrusion

Pipe

SEM

Water pipe

1679

••in SAN

500

SAN

Extrusion

1680

••with fibrils

322

SB


1681 Notch effect:

AL SEM

Definition

1682

••and notch sensitivity for PFA

385

PFA


AL

1683

••divides spherulites

510

PP

Injection molding Part of desalination

DL-POL

1684

••for PA

101

PA

(Extrusion)

Molding compound

DL-POL + 

1685

••for PA6

100

PA6

Thin section

Handle

DL-POL + 

1686

••for PVC

099

PC

Thin section

Tooth fracture

DL-POL + 

1687

••through a notch

180

PA6-GF15

Injection molding Self-locking part

AL

1688 Notch(es):

Definition

1689

••in a corrugated pipe

499

PA

Imbedding

Electrical conduit

DL-POL + 

1690

••in PA

077

PA

Thin section

Electrical conduit

DL-POL + 

1691

••sharp

463

PP

Polished sample

Membrane

AL

PCTFE

Extrusion

Bushing

AL

1692 Novice terms

Definition

1693 Nozzle, not axially aligned

165

47


Glossary

No.


Molded Part

Contrast

1694 Nozzle tip is broken off

Technical Term

165

Bushing

AL

1695 Nucleating agents:

Definition

1696

426

••or foreign material?

PCTFE PP


DL-POL

PP


1697 Numerical aperture

Definition

1698 Object micrometer

Definition

1699 Object slides

Definition

1700 Objective

Definition

1701 Objective revolver

Definition

1702 Oblique cracks

252

1703 Ocular

Definition

1704 ODSC analysis

Definition

1705 OIT analysis

Definition

1706 Operating temperature

Definition

1707 Operating temperature, not reached

588

PE


DL

1708 Operation threads in dissolution

326

Vicryl

Spinning

SEM

1709 Optical path of the pupil

Definition

1710 Optimize material costs

154

PC


AL-DF

1711 Optimizing the cavity filling

003

PA/PTFE


AL: 1 : 1

1712 Orange skin:

Definition

1713

153

ABS/PC


AL

••in the ejector area

Suture material

1714


002

PE


AL

1715

••on the entire surface

028

ABS


AL

1716

••on a mandrel half

152

POM


AL

1717

••on PA6

583

PA6


AL

1718

••on a surface area

052

ABS


AL

1719

••on ABS

515

ABS


AL

1720

••on PA6.6

393

PA6.6


AL

1721

••on PC

350

PC


SEM

1722

••on PC

191

PC


AL

1723

••partial

576

PPS


AL

1724

••typical

161

ASA


AL

ABS


AL

1725 Orange structure (see also → orange skin):

Definition

1726

539


1727

••on PBTB

511

PBTB


AL

1728

••on SAN

156

SAN


AL

1729

••partially

513

PA6-GF30


AL

1730

••through a too low molding compound temperature

155

PS


AL

1731 Orientation

Definition

1732 Orientation stresses

Definition

48


No.

Technical Term

1733 Outdoor weathering: 14 months

Molded Part

019

Extrusion

Composite pipe AL Roof sheeting

PE-RT/AL/ PE-RT

Contrast

1734

••22 years

015

ECB

Extrusion

1735

••4 years

012

PP

Injection molding Lawn chair

AL

1736

••of glass fibers

119

POM-GF30

Block ground sample

Molded part

AL

1737

••with the influence of media

014

PVC

Extrusion

Wicker chair

AL: 1 : 1

PBTB


1738 Overheating, thermal

Definition

1739 Over-injection (LM subchapter)

511–515

1740 Over-injection:

Definition

1741

511

••confusion is possible

Glossary


AL

AL

1742

••for PA6-GF30

513

PA6-GF30


AL

1743

••for PE

143

PE

Injection molding Reducer

AL

1744

••for LDPE

512

LDPE


AL

1745

••over-injection?

036

PP-GF30


AL

1746 Overload crack

549

PVC

Calendering

AL

1747 Overloading: mechanical

242

POM


1748

177

PPO

Polished sample

Water container AL

1749 Overstretching, cold

048

PP


Bottle

AL

1750 Oxidation stability

Definition

PB

Extrusion

Heating pipe

AL

PB

Extrusion

Heating pipe

AL DL-DIC + 

••in the round thread

1751 Oxidation:

Definition

1752

Definition

••stability

1753 Oxidation-induction time

Definition

1754 Oxygen corrosion

440

1755 Oxygen diffusion barrier:

Definition

1756

440

••in a composite pipe

Water bed membrane

AL

1757

••mostly of vinyl alcohol VA

066

VPE/VA

Extrusion

Pipe

1758

••of aluminum Al

256

PP-R/AL/PP-R

Extrusion

Composite pipe AL Molded part

1759 Packaging and transport

Definition

1760 Paint: aging

210

SB

Vaporizing

1761

••bubbles

205

PA6-GF30

Injection molding Frame

AL

1762

••bubbles after cooking test

203

ABS


AL

AL-DIC + 

1763

••bubbles are drops of paint

200

PBT

Coating

1764

••chipping (2C high quality finish)

211

PA6-GF30/PE


AL

1765

••degassing?

206

PA6-GF30

Scalpel section

Frame

AL-DF

Fan blade

Fan blade

AL

1766

••nozzle, washed out

199

PBT

Coating

1767

••outbreaks

204

ABS


AL

1768

••refreshed with solvents

210

SB

Thinning

Molded part

AL-DIC + 

1769

••with burn streak

AL

547

—

Coating

Coated surface

AL-DF

1770 Paint drops, deformed

210

SB

Vaporizing

Part

AL-DIC + 

1771 Paint embrittlement:

Definition

1772

204

ABS


••embrittlement

AL

49


Glossary

No.


1773 Paint flake

Technical Term

199

Molded Part

Contrast

PBT

Coating

Fan blade

AL

1774 Paint streaks

Definition

1775 Paint thinner, excessive 1776 Paint warp

198

PA6

Coating

Handle frame

AL

197

PA6


AL

ABS

Injection molding Wall connector

AL: 1 : 1

1777 Paintability:

Definition

1778

250

••examine with the wetting test

1779 Painting (LM subchapter)

197–213

1780 Painting (SEM subchapter)

355–356

1781 Painting

Definition

1782 Painting error:

Definition

SEM

1783

••bubble in 1C paint

355

Sheet

Coating

Can

SEM

1784

••bubble in 2C paint

356

ABS

Coating

Cover

SEM

1785

••bubbly area

212

PA6-GF30/PE


Chair

AL

1786

••displacement of the coversheet

098

—


Layer of coating

DL-POL + AL

1787

••for PA6-GF30/PE

211

PA6-GF30/PE


AL

1788

••in 1C paint

355

Sheet

Coating

Can

SEM

1789

••in 2C paint

356

ABS

Coating

Cover

SEM

1790

••in PA6

197

PA6


AL

1791

••paint cracks through molded part cracks

208

CAB

Thin section

DL-POL + 

Housing

1792

••paint warps in PA6

198

PA6

Coating

Handle frame

AL

1793

••painting error?

261

PC

Thin section

Fan cover

AL

1794

••top coat displacement

546

—

Coating

Coated surface

AL

1795 Palladium conducting layer (existing)

277

ABS

Electroplating

Cover

AL

1796 Parallel cracks in finger prints

252

PP


1797 Particle (LM subchapter)

279–294

1798 Particle (SEM subchapter)

363–364

1799 Particle:

Definition

SEM

1800

••as a top-coat delamination

547

—

Coating

1801

••black burnt

285

PA6.6


AL

1802

••close to crack

555

C-PVC

Extrusion

Water pipe

AL

Water pipe

Coated surface

1803

••close to crack

556

C-PVC

Polished sample

1804

••film-like, in the needle-shut off nozzle area

283

PS


AL-DF

AL-DIC AL

1805

••inhomogeneous distribution

045

PETP

Injection molding Part of housing

AL-DF

1806

••on a paint surface

546

—

Coating

Coated surface

AL

1807

••pulled out

561

PBT/PC

Block section

Housing

AL-DF

1808

••sharply edged, hard to melt

285

PA6.6


AL

1809

••unmelted

291

PE

Extrusion

Pipe interior

AL

1810

••unmelted

292

PVC

Extrusion

Water pipe

AL

1811

••unmelted with glass fibers

039

PP-GF30

Polished sample

Light well

AL

1812

••white

126

PE

Extrusion

Pipe

DL

50


No.

Technical Term


1814 Parting plane

Definition

1815 Perforated disc

Definition

1816 Perforated disc imprinting:

Definition

PP

Molded Part


Contrast SEM

Glossary

1813 Particle inclusions

1817

••in PE

127

PE

Extrusion

Water pipe

DL

1818

••in PP

452

PP

Thin section

Pipe

DL

1819

••in TEEE

134

TEEE

Extrusion

Vacuum line

AL

1820 Permeation layer: in an oil tank

056

PA

Thin section

Oil tank

DL-POL + 

1821

422

PE


Wall of oil container

AL

PE


Bottle

DL-POL

PE63

Thin section

Water pipe

DL

••on an oil container wall

1822 Phase contrast, AL-PH and DL-PH

Definition

1823 Phase displacement

Definition

1824 Photoelasticity

137

1825 Pigment conglomerate:

Definition

1826


405

1827

••over 80 µm

Definition

1828


294

PE

Extrusion

Water pipe

DL

1829

••fine

117

PA6.6-GF30

Thin section

Handle

DL

Sheet, PP

1830

••fine

183

PP

Thin section

1831

••spherical

351

PVDF


SEM

HDPE

Extrusion

Sewer pipe

DL

ABS

Thin section

Siphon

DL

1832 Pigment determination

Definition

1833 Pigment distribution, poor

445

1834 Pigment streaks:

Definition

1835

446

••are weak spots

DL

1836

••black (through contaminations)

132

ABS

Injection molding Thermos flask

AL

1837

••bright (noncolored molding compound)

127

PE

Extrusion

Water pipe

DL

1838

••concentric

Definition

1839

••dark

499

PA

Imbedding

Electrical conduit

DL-POL + 

1840

••fainted, crack

455

ABS

Thin section

Rotary clothes line

DL

1841

••many with vacuoles

522

AMMA

Injection molding Holder

DL

1842

••through poor homogenization

077

PA

Block ground sample

Electrical conduit

DL-POL + 

1843

••through subsequent coloring

425

PP

Thin section

Warming tray

AL

1844


446

ABS


DL

1845


523

POM

Thin section

DL

1846

••weaken the strength

455

ABS

Injection molding Rotary clothes line

DL

1847 Pigment wash-out:

117

PA6.6-GF30

Thin section

Handle

DL

1848

559

PVC

Extrusion

Pipe

AL: 1 : 1

469

PE

Thin section

Sheet

DL

••vermicular, on the inner surface of a pipe

1849 Pigment-free streaks

Bearing seat

51


Glossary

No.

Technical Term


Molded Part

Contrast

1850 Pigments:

Definition

1851

••reduce matrix bonding

351

PVDF


SEM

1852

••reduce the molded part strength

AL

425

PP


1853 Pinch-off weld in the mold separation 084

PE

Extrusion

Corrugated pipe AL

1854

••overload

051

PE


Diesel can

AL

1855

••V-shaped

083

PE


Diesel can

AL

1856

••with stress whitening

051

PE


Diesel can

AL

1857 Pinking

Definition

1858 Pinking test

Definition

1859 Pinpoint gate: deeply sheered out

002

PE


AL

1860

••frozen

076

PA/PTFE

Thin section

AL

1861

••frozen

533

1862

••with center vacuole in PA6.6‑GF30 524

Piston ring

POM


DL-POL

PA6.6-GF30


AL

1863

••with center vacuole in POM

525

POM


AL

1864

••with cold flow lines

146

POM


AL

1865

••with wetting agent cracks

488

ABS/PC

Injection molding Push button

AL

1866 Pinpoint heating during lasering

217

PC

Laser

Printer cover

AL + DL

1867 Pipe extrusion

Definition

1868 Pipe: crack investigation

043

PVC

Extrusion

Water pipe

AL AL

1869

••core-foamed

423

PVC-U

Foaming

Pipe

1870

••expansion through pressure

020

PE-RT/AL/ PE-RT

Extrusion

Composite pipe AL

1871

••fixation is dissolved too early

466

PE100

Extrusion

Gas pipe

AL

1872

••fracture through carbon black conglomerate

047

C-PVC

Extrusion

Pipe

AL

1873

••insertion without guide rollers

466

PE100

Extrusion

Gas pipe

AL

1874

••line testing (cracks)

397

PP

Extrusion

Pipe

AL

1875

••surface, scraped

545

PE100

Extrusion

Gas pipe

AL

1876

••transfer with problems

467

PE

Laying pipe

Gas pipe

AL: 1 : 1

PC-GF35

Thin ground sample

Molded part

DL-POL

1877 Plan apochromatic objective

Definition

1878 Plastic binding, missing

116

1879 Plastic behavior, understanding

Definition

1880 Plastic burr:

Definition

1881

••ABS

515

ABS


AL

1882

••causes expensive rework

514

PE


AL

1883

••for PC

457

PC


AL

1884

••through mold breathing

514

PE


AL

POM

Thin section

DL-POL + 

1885 Plastic core:

Definition

1886

300

••in POM

1887 Plastic deformation

52

Definition

Housing


No.

Technical Term


1889 Plastic materials (see also table in the appendix):

Definition

1890

••amorphous

Definition

1891

••conduct heat badly

521

1892

••crosslinked

Definition

1893

••determine

Definition

1894

••LM subchapter

195–196

1895

••semicrystalline

Definition

1896 Plastic matrix-integration of glass fibers

213

1897 Plastic melt

Definition

1898 Plastic particle, nonmelting

086

1899 Plasticization unit

Definition

1900 Plasticizer migration:

Definition

1901

Molded Part

Contrast

PA6.6-GF25

Fracture surface

Housing

AL

PA6-GF30/PE


Armrest

AL

PE


Multilayer film

DL-POL

Glossary

1888 Plastic embrittlement

244

C-PVC

Extrusion

Water pipe

AL: 1 : 1

1902 Plasticizers generate fungus growth

295

PC

Extrusion

Optical fiber conduit

DF-AL

1903 Plasticizing

Definition

1904 Plasticizing errors

Definition

1905 PMMA layer, 50 µm

010

PVC-U

Extrusion

Window profile

AL

1906 Pocket cracks in the surface

359

PP

Rotational molding

Surface

SEM

1907 Point analysis

Definition PA6.6-GF30

Thin ground sample

Cover

DL-POL + DIC

••generates severe swelling

1908 Polarization:

Definition

1909

115

••weak, for PA6.6-GF30

1910 Polarization contrast (AL-POL and DL-POL):

Definition

1911

••colored, in comparison

186

PP

Thin section

Sheet, PP

DL-POL + 

1912

••noncolored

185

PP

Thin section

Sheet, PP

DL-POL

1913 Polarization optics

Definition

1914 Polarized light

Definition

1915 Polarizer (polarizing filter)

Definition

1916 Polarizing filter

Definition

1917 Polished sample:

Definition

1918

••electro fusion welding

474

PE

Polished sample

Water pipe

AL

1919

••heating element weld line (good)

463

PP

Polished sample

Pressure membrane

AL

1920

••colored with alcohol and fuchsine

079

PVC/Acryl

Polished sample

Window profile

AL-DIC

1921

••composite film

436

PE/PETP/PA

Polished sample

Multilayer film

AL

1922

••friction weld line

468

ASA

Polished sample

Housing

AL

1923

••heating element weld line (poor)

462

PP

Polished sample

Pressure membrane

AL

53


No.

Glossary

1924

Technical Term ••heating element weld line with welding factor of 1


Molded Part

Contrast

483

Weld line

AL

PE

Heated tool welding

1925

••shows a rubber seal in comparison 550

PA6.6-GF30

Polished sample

Cooling unit

AL

1926

••shows part tolerances

552

PC

Polished sample

Clutch

AL

1927

••shows the joint depth of the pipe

475

PB

Polished sample

Socket

AL

1928

••T-butt joint

484

PP

Extrusion welding T-butt weld

AL

1929

••ultrasound weld lines

478

PP

Imbedding, EP

Float

AL

Filter

1930

••weld line with uneven MFR

471

PP

Polished sample

1931

••with etching (chromo-sulfuric acid) 358

SB


SEM

1932

••with large vacuoles and micro vacuoles

520

PBTP-GF20


AL

1933

••with weld line width (welding stress)

480

PE100

Extrusion

AL

Weld line

AL

1934 Polishing

Definition

1935 Polishing agent

Definition

1936 Polishing cloths

Definition

1937 Polyester fibers

339

FEP


SEM

1938 Polyether foam

420

PUR

Foaming

AL

1939 Polymer blend:

Definition

Polyether

1940

••ABS/PC with cold flow front

581

ABS/PC


AL

1941

••ABS/PC with not fully injected molded part wall

579

ABS/PC


AL

576

1942

••ABS/PC with poor impression

1943

••PA/PE hub cap with paint intrusion 207

1944

••physical

1945

••PP/PE surface with foreign particle 289

561

1946 Polymer mixture

561

1947 Polymerization

Definition

ABS/PC


AL

PA/PE

Thin section

DL

PBT/PC


Hub cap

AL-DF

PP/PE-Blend


AL-DF

PBT/PC

Block section

Housing

AL-DF

1948 Post-crystallization:

Definition

1949

••in a PE63 pipe angle

467

PE

Extrusion

Gas pipe

AL: 1 : 1

1950

••with vacuole formation

517

PE

Block ground sample

Handle

AL

PE

Block ground sample

Handle

AL

PP

Extrusion

Water pipe

AL

PA6.3


AL: 1 : 1

1951 Post-shrinkage:

Definition

1952

517

••creates vacuoles

1953 Powder coating

Definition

1954 PP cancer through copper attack

235

1955 Pre- and post-treatment

Definition

1956 Predetermined fracture point:

Definition

1957

049

••for PE100

1958 Predrying:

Definition

1959

318

PC

Injection molding Thermostat valve

SEM

471

PP

Polished sample

AL

••poor

1960 Preheating time too short for hot tool welding of PP

54

Filter


No.

Technical Term

Molded Part

Contrast

471

Filter

AL

1962 Preliminary examination

Definition

1963 Preload through steel spring 1964 Preparation: of an electroplating bubble 1965

••in nitrogen N2

1966 Preparation agent

PP

Polished sample

062

PA6.6


AL

270

POM

Preparation

Door handle

AL

420

PUR

Foaming

Polyether

AL

—

Microtome

Definition

1967 Preparation devices:

Definition

1968

103

••for thin section placement

AL: 1 : 1

1969 Preparation techniques

Definition

1970 Pressure overload

390

PB

Extrusion

Heating pipe

AL

1971 Pressure point in a pipe (lithographic print)

401

PVC-U

Extrusion

Pipe

AL

1972 Pressure test, premature

389

PVC

Extrusion

Water pipe

AL

1973 Pressure variations during painting

199

PBT

Coating

Fan blade

AL

1974 Pretreatment

Definition

1975 Primary colored molding compound

Definition

1976 Primary forming

Definition

1977 Priming

Definition

1978 Printing

Definition

1979 Processing aids for WPC

196

WPC

Extrusion

Profile

AL: 1 : 1

1980 Processing parameters:

Definition PE

Injection molding Head rest

1981

••cold

1982 Processing, good and too cold:

064

AL

Definition

1983

••too cold at PA6-GF30

513

PA6-GF30


AL

1984

••too cold PA6

583

PA6


AL

1985 Prognosis for the future

015

ECB

Extrusion

AL

1986 Progress report

Definition

1987 Propellant additive

154

PC


AL-DF

1988 Punched hole: edge bead (plastic deformation)

060

ABS

Injection molding Mounting base

AL

1989

558

LDPE

Blown film

AL

••frayed

Roof sheeting

Stretch film

1990 PUR foam: closed-celled

371

PUR

Foaming

Foam

SEM

1991

••open-celled, with removed membranes

372

PUR

Foaming

Mattress

SEM

1992

••slightly closed celled

373

PUR

Foaming

Foam

SEM

PVC U

Extrusion

Pipe

AL-DF

1993 Quality

Definition

1994 Quality error (molded part)

Definition

1995 Quality influences: during extrusion

Definition

1996

Definition

••during injection molding

Glossary


1961 Preheating zone, clearly visible

1997 Quality tests, comparing

Definition

1998 Question of guilt: clarify (pipe manufacturer was to blame)

281

55


Glossary

No.


Molded Part

Contrast

1999

Technical Term ••crack or cut?

543

PE100

Extrusion

Gas pipe

AL

2000

••who is to blame?

208

CAB

Thin section

Housing

DL-POL + 

2001 Question of guilt and assignment of guilt

274

PA6.6

Electroplating

Clamp

AL

2002 Questions for the customer for the expert opinion

Definition

2003 Quickmarks

Definition

2004 Radial groove in a friction welding seam

468

ASA

Polished sample

Housing

AL

2005 Radiation crosslinking

Definition

2006 Radiation protection

Definition

2007 Rayleigh criteria

Definition

2008 Razor blade cut: for PUR closed-celled 371

PUR

Foaming

Foam

2009

PUR

Foaming

Mattress

••for PUR foam open-celled

372

SEM

2010 Record grooves: at the pinpoint gate

158

PC

Injection molding Clock hand

AL

2011

••concentric

146

POM


AL

2012

••concentric

162

SAN


AL

AL + DL

2013 Red coloring of PVC

Definition

2014 Redirecting the crack

Definition

2015 Refinement

Definition

2016 Reflected light:

Definition

2017

••combined with transmitted light

413

ASA

Extrusion

2018

••illumination

106

—

Microscope

PP

Thin section

Board PP

DL-PH

Connector

AL

2019 Refractive index n: 2020

Sheet

AL: 1 : 1

Definition

••In the transmitted light and phase 184 contrast DL-PH

2021 Regranulate

Definition

2022 Regranulate additive: for PA6.6

129

PA6.6

Polished sample

2023

522

AMMA

Thin section

Bracket

DL

2024 Regranulate content, undesired

552

PC

Polished sample

Clutch

AL

2025 Reinforcement (LM subchapter)

565–567

••for AMMA

2026 Reinforcing materials:

Definition

2027

••for PPS

341

PPS

Injection molding Measurement equipment

SEM

2028

••for WPC

196

WPC

Extrusion

Profile

AL: 1 : 1

2029 Relaxation: in a pipe angle

467

PE

Extrusion

Gas pipe

AL: 1 : 1

2030 Release agent

Definition SB


2031 Release agent residue:

Definition

2032

241

••on a SB-TV rear panel

2033 Relief

Definition

2034 Report (types)

Definition

2035 Report preparation, fast and competent

Definition

2036 Residual granulate:

Definition

56

AL-DF


No.

Technical Term


Molded Part

Contrast

••large amount

136

PE


AL

2038

••residual granulate?

183

PP

Thin section

DL

Sheet, PP

2039

••residual granulate?

184

PP

Thin section

Sheet, PP

DL-PH

2040

••unmelted

454

PE-X

Thin section

Pipe

DL

2041

••with flow lines

123

PETP


DL-POL + 

2042

••with poor matrix bonding

280

PE

Extrusion

Protective conduit

AL

2043

••with spherulite structure

128

PE

Heated tool welding

Sheet

DL

2044

••with spherulites

185

PP

Thin section

Sheet, PP

DL-POL

2045 Residual mass cushion: ineffective (pinpoint gate froze)

533

POM

Thin section

Bracket

DL-POL

2046

••ineffective (holding pressure dropped too early)

534

POM


DL-POL + 

2047

••is missing

524

PA6.6-GF30


AL

2048 Residual moisture:

Definition

2049

••blame for paint bubbles?

206

PA6-GF30

Scalpel section

Frame

AL-DF

2050

••in PVC created blowhole

224

PVC

Extrusion

Sheet

AL

2051 Residual monomers

Definition

2052 Residue:

Definition

2053

••fatty white deposit

240

PBTP-GF20


2054 Residue of old paint in chamber

199

PBT

Coating

Ventilator blade AL

2055 Residues

Definition

2056 Resistance to chemicals

Definition

2057 Resolution, microscopic

Definition PUR

Casting

Spoiler

AL-DF

2058 Retained samples:

Definition

2059

025

••are important

AL

2060 Reticle

Definition

2061 Reversal of the flow front (mass inversion):

Definition

2062

••by injecting too quickly

099

PC

Thin section

Tooth fracture

DL-POL + 

2063

••with notch effect

100

PA6

Thin section

Handle

DL-POL + 

2064 Rework due to injection burr

514

PE


AL

2065 Rheological error

Definition

2066 Ring light

Definition

2067 Ring vacuole in a mass accumulation 530

PA11

Specimen

AL

2068 Rivet deformation

496

PC


AL

2069 Room temperature fracture

Definition

2070 Rotational molding

Definition

2071 Roughness: of PVC-U

009

PVC-U

Extrusion

AL

2072

497

PC


AL

179

HDPE


AL

••at the pinpoint gate

2073 Round thread: in HDPE with a sharp root of the thread

Water filter

Window profile

57

Glossary

2037


No.

Glossary

2074

Technical Term ••in a PE-sealing cap

2075 Runner plate, centrical


Molded Part

Contrast

408

PE

Polished sample

Sealing cap

AL

033

POM


AL

PA/PTFE


AL: 1 : 1

2076 Runner:

Definition

2077

003

••10 cavities

2078

••16 cavities with void

495

PC


AL

2079

••16 cavities, overview

494

PC


AL: 1 : 1

2080

••symmetry balance

003

PA/PTFE


AL: 1 : 1

2081 Rust deposits, brown

559

PVC

Extrusion

AL: 1 : 1

2082 Safeguarding through queries to the client

581

ABS/PC


AL

2083 Salt crystals on a surface

352

PP


SEM

2084 Salt flower on a matte nickel layer

268

ABS

Electroplating

ABS-Cover

AL

2085 Sample focusing

Definition

2086 Sample halving for a better understanding

177

PPO

Polished sample

Water container

AL

2087 Sample preparation for LM samples

Definition

2088 Sample preparation for SEM samples:

Definition

2089

••microcracks made visible by bending

013

EPDM

Extrusion

Sealing profile

AL

2090

••with halving of the molded part

179

HDPE


AL

PEEK


SEM

PP

Thin section

Sheet, PP

DL-POL + 

2091 Sample preparation, machining

Definition

2092 Sample surface, in SEM destroyed

325

2093 Sample table

Definition

2094

186

••rotation changes colors

Pipe

2095 Sawing

Definition

2096 Scalpel cut:

Definition

2097

••crack or cut?

548

PVC

Calendering

Water bed membrane

AL

2098

••intentional

549

PVC

Calendering

Water bed membrane

AL

2099

••shows film layers

085

PE

Coextrusion

Carrier bag

AL

2100

••through alleged paint bubble

200

PBT

Coating

Fan blade

AL

2101

••through electroplating bubble

270

POM

Preparation

Door handle

AL

2102

••through fungi

366

Si

Casting


SEM

PA6.6


2103 Scanning electron microscopy (SEM microscope)

Definition

2104 Scattered light

Definition

2105 Scrape the oxidation layer

Definition

2106 Scraping

Definition

2107 Scratches:

Definition

2108

381

••on PA6.6

2109 Screen pack:

58

Definition

SEM


No. 2110

Technical Term


Molded Part

Contrast

451

Water pipe

DL-POL + 

PE

Extrusion

2111 Screw

Definition

2112 Screw expanding forces

520

PBTP-GF20


AL

2113 Screw guidance, sloped

418

PC-CF10


AL

2114 Screw size: L : D ratio is too large

035

PE

Extrusion

Sheet

AL

2115

453

PE

Extrusion

Sheet

DL

2116 Screw speed, too low

280

PE

Extrusion

Protective conduit

AL

2117 Screw tightening torque, high

060

ABS


AL

2118 Screwing: for HDPE

178

HDPE


AL

2119

••not tight for PPO

177

PPO

Polished sample

Water container

AL

2120 Screwing moment: with crack initiation

409

PE

Polished sample

Screw cap

AL

2121

410

PE

Polished sample

Screw cap

AL

479

PP

Thin section

Float

DL-POL

POM

Extrusion

Rail

AL

••L : D ratio is too large

••without crack initiation

2122 Seam offset for ultrasonic seam

Glossary

••with pigment and spherulite streaks

2123 Search examples with technical terms Definition 2124 Seating force of the nozzle is too low 222 2125 Secondary valence forces

Definition

2126 Segregation

Definition

2127 Seizure marks and plastic abrasion

062

PA6.6


AL

2128 Self-cutting screw, expanding forces

520

PBTP-GF20


AL

2129 Self-serving allegations: from the customer

182

PC


2130


DL-POL

540

PVC

2131 SEM figure numbers in the book, all

307–381

SEM

2132 SEM microscope

Definition

2133 Semicrystalline plastics (see → types of plastic materials)

Definition

2134 Semifinished part

Definition

2135 Semifinished part quality during extrusion

Definition

2136 Separation seam

Definition

••from the customer

2137 Separation through: breaking by hand 342

PLA98

Medical comparison

Implant pin

SEM

2138

••He-laser

349

PLA98

Medical comparison

Implant pin

SEM

2139

••jet-cutting process

348

PLA98

Medical comparison

Implant pin

SEM

2140

••oscillating saw

344

PLA98

Medical comparison

Implant pin

SEM

2141

••oscillating saw

345

PLA98

Medical comparison

Implant pin

SEM

2142

••surgical tongs

343

PLA98

Medical comparison

Implant pin

SEM

59


Glossary

No.


Molded Part

Contrast

2143

Technical Term ••thermal loop at 295 °C

346

PLA98

Medical comparison

Implant pin

SEM

2144

••thermal loop at 400 °C

347

PLA98

Medical comparison

Implant pin

SEM

2145 Service life

Definition

2146 Shape stains and matte spots

Definition

2147 Shaping is too late

077

PA

Block ground sample

Electric ductwork

DL-POL + 

2148 Shear cracks in a random dome

414

ETFE

Coating

Radome dome

AL

2149 Shear flow, glass fibers

119

POM-GF30

Block ground sample

Molded part

AL

2150 Shear force influence

551

PA6.6-GF30

Polished sample

Cooling unit

AL

2151 Shear stress

430

PC

Forming under pressure


AL

2152 Shear zone:

Definition

2153

••in a welding seam

056

PA

Thin section

Oil tank

DL-POL + 

2154

••in PP spherulites

055

PP

Thin section

Filter

DL-POL

470

PP100

Thin section

Water pipe

DL-POL + 

Spherulite

DL-POL + 

2155 Shear zones with welding bead 2156 Shearing

Definition

2157 Shot (during injection molding)

Definition

2158 Shot weight

Definition

2159 Shrinkage:

Definition

2160

••between spherulites

507

POM

Thin section

2161

••extreme

493

SAN


DL AL: 1 : 1

2162

••for PBT T40

568

PBT T40


2163

••for PP

001

PP

Injection molding Protective cover AL

2164 Shrinkage compensation:

Definition

2165

••is missing

524

PA6.6-GF30


AL

2166

••is missing

525

POM


AL

2167

••is missing (large vacuole)

534

POM


DL-POL + 

2168

••is missing (vacuole creation)

533

POM


DL-POL

2169 Shrinkage cracks: on a brass inserts

386

ABS


AL

2170

398

SAN


AL

2171 Shrinkage fibrils

376

PPO

2172 Shrinkage stresses

007

PA/PTFE

2173 Shrinking:

Definition

••through shrinking on

Molded part

SEM


2174

••during welding (blown film)

085

PE

Coextrusion

Carrying bag

AL

2175

••in a pipe diameter

327

PE-X

Extrusion

Pipe, crosslinked

SEM

Si

Casting


SEM

2176 Shrinking on

Definition

2177 Sickle aperture

Definition

2178 Silane crosslinking

Definition

2179 Silicone decomposition due to fungi

365

60


No.

Technical Term


Contrast


Multilayer film

AL + DL + POL

PE


Multilayer film

DL-POL

Definition

2181 Single-layer film: with intentional film scratches

093

PE

2182

092

••with film scratches

2183 Sink mark(s):

Definition

2184

••after demolding

516

PE


AL

2185

••are reduced through propellant additives

154

PC


AL-DF

2186

••in a molded part surface

573

PA11


AL

2187

••large

572

CP


AL DL-POL

2188 Slip-stick effect:

Definition

2189

094

PE


2190 Slipway deformation, higher

062

PA6.6


AL

2191 Slit die extrusion

Definition

2192 Socket joint: nonstandard

174

PVC

Adhesion

Pipe sleeve, adhesive joint

AL: 1 : 1

2193

••THF adhesive with UV light (366 nm) visible

176

PVC

Adhesion


AL: 1 : 1

2194

••with adhesive residues

175

PVC

Adhesion


AL: 1 : 1

464

PB

Socket welding

T-fitting

AL: 1 : 1

••for PE

2195 Socket joint weld line: poorly welded

Multilayer film

2196

••with crack

465

PE100

Polished sample

Gas pipe

AL

2197

••with crack

466

PE100

Socket welding

Gas pipe

AL

2198 Soft-coat with bubbles: for PA6-GF30 205

PA6-GF30

Injection molding Frame

AL

2199

PA6-GF30

Scalpel section

Frame

AL-DF

PA6-GF30

Scalpel section

Frame

AL-DF

SB

Vapor deposition

Molded part

AL-DIC + 

••for PA6-GF30

206

2200 Solution, quick

Definition

2201 Solvent evaporation:

Definition

2202

206

••from the coated surface?

2203 Solvents for plastics

Definition

2204 Solvents: additive in the paint

210

2205

••influence creates tension cracks

262

PA/PE

Thin section

Hub cap

DL

2206

••penetration depth

262

PA/PE

Thin section

Hub cap

DL

2207

••penetration into the molded part

207

PA/PE

Thin section

Hub cap

DL

2208

••reduce amount

207

PA/PE

Thin section

Hub cap

DL

Film

DL + AL

2209 Speck:

Definition

2210

••for PE

095

PE


2211 Spherulite cracks

510

PP


DL-POL

2212 Spherulite deformations

Definition

2213 Spherulite growth

Definition

2214 Spherulite growth rate

509

POM

Thin section

DL-POL + 

2215 Spherulite streaks:

Definition

Molded part

61

Glossary

Molded Part

2180 Silver streaks


Glossary

No.


Molded Part

Contrast

2216

Technical Term ••in PA6

100

PA6

Thin section

Handle

DL-POL + 

2217


505

PA6.6

Thin section

Molded part

DL-POL + 

2218


504

PA

Thin section

Molded part

DL-POL + 

2219 Spherulite stretching volume shrinkage

057

PA

Thin section

Oil tank

DL-POL + 

2220 Spherulite structure, atypical

426

PP

Thin section

Warming tray

DL-POL

2221 Spherulites (LM subchapter)

501–510

2222 Spherulite(s):

Definition

2223

••extremely homogeneous spherulite structure

503

PA6

Thin section

Spherulite

DL-POL + 

2224

••in a welding bead

502

PP

Thin section

Water pipe

DL-POL + 

2225

••in PA

504

PA

Thin section

Molded part

2226

••in PA

510

PP


DL-POL +  DL-POL

2227

••in the residual granulate

184

PP

Thin section

Sheet, PP

DL-PH

2228

••in the residual granulate

185

PP

Thin section

Sheet, PP

DL-POL

2229

••large and small spherulites

100

PA6

Thin section

Handle

DL-POL + 

2230

••large and small spherulites

101

PA


DL-POL + 

2231

••mixing spherulites

099

PC

Thin section

Tooth fracture

DL-POL + 

2232

••of PA are similar to sugar crystals

194

White sugar


Refined sugar

DL-POL + 

2233

••of the same size

303

PA

Thin section

Part

DL-POL + 

2234

••sheared (with crack)

055

PP

Thin section

Filter

DL-POL

2235

••spherulite growth

501

PP

Thin section

Spherulite

DL-POL + 

Lid

AL: 1 : 1

2236 Split ground sample

Definition

2237 Splitting of ether links for POM

246

POM

Compression molding

2238 Sprocket with poor impression

583

PA6


AL

2239 Sprue (LM subchapter)

001–005

2240 Sprue:

Definition

2241

••with burn streaks

539

ABS

Injection molding Circuit board

AL

2242

••with calotte (dome)

147

ABS


AL

2243

••with cold-flow lines

158

PC

Injection molding Clock hand

AL

2244

••with cold-flow lines

182

PC


AL

2245

••with crack

395

PPSU


AL

2246

••frozen

152

POM

Injection molding Actuator

AL

2247

••frozen

301

POM

Thin section

DL-POL + 

2248

••with internal stress

488

ABS/PC


Snap fit

AL

2249

••not frozen

306

POM

Thin section

2250

••with orange skin

539

ABS

Injection molding Circuit board

AL

2251

••pin gate, stripped

005

PA6


AL

2252

••ring gate

159

PA4.11


AL: 1 : 1

62

Torsion bar

DL-POL + 


No.

Technical Term


Molded Part

••with shrinkage cracks in material accumulation

396

PPSU


2254

••with surface roughness

Contrast AL

497

PC


AL

2255 Sprue area: with cold flow lines

144

PS


DL + AL

2256

004

POM


AL

••with crack

2257

••with fibrils and bulge

037

PP-GF30


AL

2258

••with microvoids

532

PP-GF40


AL

2259

••with orange skin

004

POM


AL

PUR

Foaming

Foam

SEM

LDPE

Blown film

Stretch film

AL

PE

Extrusion

Sheet

DL

ABS

Electroplating

Cover

AL

SAN


DL

2260 Sputtering (gold plating):

Definition

2261

371

••of PUR

2262 Sputtering layer (gold layer)

Definition

2263 St. Andrew’s cross DBL 7384 and DBL 7399

Definition

2264 Stab injury

558

2265 Stabilizer(s)

Definition

2266 Stagnation pressure:

Definition

2267

453

••too low

2268 Stains:

Definition

2269

267

••black

2270 Steel needle

Definition

2271 Stereomicroscope

Definition

2272 Strainer impression:

Definition

2273 Strand formation

Definition

2274 Streaks (LM subchapter)

445–460

2275 Streaks:

Definition

2276

••brown

Definition

2277

••brown

Definition

2278

••brown burn streak

447

2279 Stress center

Definition

2280 Stress crack corrosion

Definition

2281 Stress crack test

Definition

2282 Stress crack(s): in PA

260

PA


AL

2283

486

PE100

Flame treatment

Gas pipe

AL

Gas pipe

••in PE100

2284

••PE100

487

PE100

Extrusion

2285

••in PPSU

395

PPSU


AL

2286

••through groove

180

PA6-GF15

Injection molding Clamping mechanism

AL

2287

••through groove

181

PA6-GF15

Polished sample

Clamping mechanism

AL AL

AL

2288

••through media influences

489

PA6.6


2289

••through solvents

173

PA6

Adhesion

Car door handle AL

PE


Diesel can

2290 Stress whitening:

Definition

2291

051

••in a pinch-off weld

Glossary

2253

AL

63


No.

Glossary

2292

Technical Term ••in a snap-in hook

2293 Stresses (LM subchapter)

Figure No. Type of Plastic Processing 052 Definition

2295

074

2296 Stresses in the molded part:

Definition

2297

236

••create cracks in the wetting agent test

Contrast


AL

PE

Blown film

DL-POL

SAN

Injection molding Filter cup

485–500

2294 Stresses: ••through stretching

Molded Part

ABS

Blown film

AL: 1 : 1

2298

••create cracks through media attack 234

SB

Vacuum forming

Cleaning tray

AL

2299

••create shell cracks

384

PMMA

Vacuum forming

Dome light

DL

2300

••in a mandrel

519

PBTP-GF20


AL

2301

••in a PVC pipe

399

C-PVC

Extrusion

Fitting

AL

2302

••production-related

551

PA6.6-GF30

Polished sample

Radiator

AL

2303

••through injection molding

490

SAN


DL

2304

••underneath the paint

261

PC

Thin section

Ventilation cover

AL

2305

••visible through hot air treatment

465

PE100

Socket welding

Gas pipe

AL

2306

••visible through wetting agent test

496

PC


AL

2307 Stretch film: with hole or stab injury? 557

LDPE

Blown film

Stretch film

AL

2308

558

LDPE

Blown film

Stretch film

AL

2309 Stretched tip

512

LDPE


AL

2310 Stretching area, cold

082

PE


Diesel can

AL

2311 Strips

Definition

2312 Structure, inhomogeneous (poor homogenization)

453

PE

Extrusion

Sheet

DL

2313 Structure, semicrystalline

185

PP

Thin section

PP sheet

DL-POL

2314 Structure study

Definition

2315 Styrene globules

358

SB


SEM

2316 Subcontraction

Definition

2317 Surface error:

Definition


2318 Sulfate ash content

Definition

2319

••dirt deposits

012

PP

Injection molding Garden chair

AL

2320

••grease residues

240

PBTP-GF20


AL

2321

••insular dissolution after weathering 308

PP-UV stable

Injection molding Lounger, UV stable

SEM

2322

••mechanical

511

PBTB


AL

2323

••surface, good and poorly painted

202

ABS


AL

2324

••surface, painting

547

—

Coating

AL-DF

Coated surface

2325

••surface, ripped-open

377

PEEK


SEM

2326

••surface, rough

063

PA6.6

Injection molding Streaks

AL

2327

••surface, unpainted, without errors 201

ABS


AL

2328

••surface, weathering

008

PVC-U

Extrusion

AL

325

PEEK


2329 Surface: destruction

64

Window profile

SEM


No.

Technical Term


••discoloration

Definition

2331

••refining

Definition

Molded Part

Contrast

2332 Surface finish: with good matrix adhesion

331

PC-GF25


2333

336

PPO-GF35


SEM

2334 Surface layer delamination

393

PA6.6


AL

2335 Surface layer, very cold

527

POM

Injection molding Pipe bracket

AL

2336 Surface loads through electrons

325

PEEK

Injection molding Fastener

SEM

2337 Surface pressure, slide bars

061

PA6.6


AL

2338 Surface stress

Definition

2339 Swan neck lighting

Definition

2340 Symmetry balance

003

PA/PTFE


AL: 1 : 1

2341 Systematic errors

Definition

2342 Talcum conglomerate up to 62 µm

567

PP-T40


DL

2343 Tear:

Definition

2344

322

SB


SEM

••with punctual matrix adhesion

••with sloped fibrils

2345 Tear zone: in ABS

312

POM


SEM

2346

313

POM


SEM

2347 Temperature increase due to browning 023 caused by outdoor weathering

PVC


DL

••in POM

2348 Temperature influence

Definition

2349 Tempering (tempered storage):

Definition

Roofing element

2350

••for ABS

570

ABS


AL: 1 : 1

2351

••for PA/PE

262

PA/PE

Thin section

Hub cap

DL

Glass holder nut DL

2352

••for PC

498

PC

Turning

2353

••for SAN

492

SAN


DL

2354

••for SAN

493

SAN


DL

2355

••prevents stress cracks

DL

207

PA/PE

Thin section

2356 Tempering, unequal, encourages warpage

568

PBT-T40


AL: 1 : 1

2357 Tensile stresses

Definition

2358 Test certificate

Definition

—

Microscope

AL: 1 : 1

2359 Test pins: test ink (for the examination of wettability)

Definition

2360

250

ABS

Injection molding Connector

AL: 1 : 1

2361 Tetrahydrofuran turns white at too-early exposure to water

389

PVC

Extrusion

Water pipe

AL

2362 TG analysis

Definition

2363 Thermal damage:

Definition

2364

••test ink

Hub cap

412

PB

Extrusion

Heating pipe

AL: 1 : 1

2365 Thermal decomposition creates blowholes

227

ABS

Vacuum forming

Tray

AL

2366 Thermal streaks

Definition

2367 Thermogravimetry TG

Definition

••of PB

Glossary

2330

65


Glossary

No.

Technical Term


2368 Thermomechanical analysis TMA

Definition

2369 Thermoplastic elastomers TPE:

Definition

2370

195

••TPE-spring element


AL: 1 : 1

389

PVC

Extrusion

Water pipe

AL

176

PVC

Adhesion


AL: 1 : 1

Thin ground sample

Thin grinding device

—

—

Definition

2372 Thermoset(s)

Definition

2373 THF: tetrahydrofuran adhesive for pipes 2374

2375 Thin grinding device to produce a thin ground sample:

Definition

2376

109

••schematic diagram

Contrast

TPE

2371 Thermoplastics

••visible in UV light (366 nm)

Molded Part

2377 Thin ground sample

Definition

2378 Thin layer chromatography

Definition

2379 Thin section (LM subchapter)

067–072

2380 Thin section:

Definition

2381

••8 µm of a blown film

074

PE

Extrusion

Blown film

DL-POL

2382

••10 µm of a piston ring

076

PA/PTFE

Thin section

Compression ring

AL

POM

Thin section

Ring

AL

TEEE

Extrusion

Vacuum line

AL

PE

Extrusion

Blown film

DL-POL

2383

••after a cold treatment

Definition

2384

••by a bar with weld line

034

2385

••comparison to thin ground sample Definition

2386

••compression

Definition

2387

••corrugated by residual stresses

134

2388

••corrugation

Definition

2389

••weld line

074

2390 Thin section device (microtome):

Definition

2391

••schematic diagram

110

—

Microtome

—

Table

2392 Thin section error: cutting error creates eruptions and nicks

070

PE

Thin section

Water pipe

DL

2393

••with air induction

072

PBT

Thin section

PBT

DL

2394

••with rippling

071

PE

Preparation

Water pipe

DL

067

PE

Preparation

Water pipe

DL

068

PE

Preparation

Water pipe

DL

069

PE

Preparation

Water pipe

DL

PE

Extrusion

Water pipe

DL

2395 Thin section placement: in Canada balsam, 1st step 2396 2397

••in Canada balsam, 2nd step rd

••in Canada balsam, 3  step

2398 Thin section, types of knives:

Definition

2399

Definition

••knife angle

2400 Thorough mixing, inhomogeneous

127

2401 Thread: distorted

417

PC-CF10

Polished sample

Housing

AL

2402

418

PC-CF10

Polished sample

Housing

AL

Housing

••distorted

2403

••distorted

419

PC-CF10

Thin section

2404

••worn on one side

178

HDPE

Injection molding Casing

66

AL AL


No.

Technical Term

Molded Part

Contrast

PC

Extrusion

Screw nut for glass

DL

2406 Thread base, sharp

179

HDPE

Injection molding Casing

AL

2407 Thread overload (in plastic)

Definition

2408 Throughput is too high

127

PE

Extrusion

DL

2409 Time fracture line

320

PVC


SEM

2410 Time savings in expert opinions

Definition PP

Extrusion welding T-butt weld

AL

••with cracks through influences of media

2411 T-joint with welding factor up to 0.95 484

Water pipe

Glossary


2405

2412 TMA analysis

Definition

2413 Toluene content in Canada balsam

411

PS

Thin section

Cover

DL

2414 Tooth fracture through pigment streaks

099

PC

Thin section

Tooth fracture

DL-POL + 

2415 Top coat delamination

547

—

Coating

Coated surface

AL-DF

2416 Top secret investigation:

098

—


Coating layer

DL-POL + AL

2417

541

PA/PTFE


AL

HDPE

Extrusion

DL

••of PA/PTFE

2418 Topography

Definition

2419 Torpedo

Definition

2420 Torpedo bridges in the extruder

445

Sewer pipe

2421 TPE (thermoplastic elastomer):

Definition

2422

195

TPE


AL: 1 : 1

314

POM


SEM

2424 Transition section, wide (Gauss curve) 095

PE


DL + AL

2425 Transition without rounding: acts as a groove

304

CP

Injection molding Threaded nut

AL

2426

180

PA6-GF15

Injection molding Clamping mechanism

AL

2427 Transmission of liquid (electroplating error)

269

PP

Thin section

DL-POL

2428 Transmitted light

Definition

2429 Transmitted light illumination

106

—

Microscope

2430 Transverse orientation of macro molecules

137

PE


2431 Tube lens

Definition

2432 Turbulence

Definition

2433 Tweezers

Definition

••TPE-spring element

2423 Transient area of the tearing zone

••benefits the fracture

Film

Mounting plate

AL: 1 : 1 Bottle

DL-POL

2434 Type of carbon black: unsuitable

287

PE

Thin section

Roof sheeting

DL

2435

••not homogenizable (wrong  masterbatch)

293

PE

Extrusion

Water pipe

DL

2436

••wrong (carbon black conglomerate 294 up to 100 µm)

PE

Extrusion

Water pipe

DL

2437 Ultrasonic cleaning

358

SB


SEM

2438 Ultrasonic inspection

172

PVC

Adhesion

AL: 1 : 1

Bonded socket joint

67


Glossary

No.


Molded Part

Contrast

2439 Ultrasonic welds: poor

Technical Term

478

PP

Ultrasonic welding

Float

AL

2440

••poor

479

PP

Ultrasonic welding

Float

DL-POL

2441

••with a good seam strength

482

POM

Ultrasonic welding

Molded part

DL-POL + 

2442

••with lower seam strength

481

POM

Ultrasonic welding

Molded part

DL-POL + 

2443 Ultrasonic weld line strength: better

482

POM

Ultrasonic welding

Molded part

DL-POL + 

2444

481

POM

Ultrasonic welding

Molded part

DL-POL + 

••lower

2445 Ultraviolet radiation (UV radiation)

Definition

2446 Ultraviolet radiation (UV radiation in outdoor weathering)

Definition

2447 Universal microscope

Definition

2448 UP-resin coating, leaking

421

UP

Coating

Resin coating

AL

2449 Use of torque wrenches

498

PC

Turning


DL

2450 UV attack with salt impact

353

PP


SEM

2451 UV cracks

382

PE-Xc

Extrusion

AL

2452 UV load through fluorescent tubes

024

SB


AL

2453 UV radiation

Definition

2454 UV spectroscopy

Definition

2455 UV stabilization: poor for PP

012

PP

Injection molding Lawn chair

AL

Heating pipe

2456

••poor for PUR foam

310

PUR foam

Foaming

Bumper

SEM

2457

••poor for PVC

023

PVC


Roofing element

DL

2458 UV stabilizer(s):

Definition

2459

016

PC


DL-DIC

2460 Vacuole: center vacuole

306

POM

Thin section

DL-POL + 

2461

••in the sprue, shows a lack of holding pressure

524

PA6.6-GF30


AL

2462

••in the sprue, shows a lack of holding pressure

525

POM


AL

••in PC-facade plate

Torsion bar

2463

••microvacuole

376

PPO

Molded part

2464

••none

242

POM


AL

2465

••still visible

301

POM

Thin section

Snap fit

DL-POL + 

2466

••with microvacuoles in the fracture area

535

PPS-GFM

Fracture area

Pipe sleeve

AL

2467

••with sink mark

516

PE


AL


AL

2468 Vacuoles (LM subchapter)

516–536

2469 Vacuoles (SEM subchapter)

375–376

2470 Vacuoles and blowholes:

Definition

2471

120

68

••and glass fibers

Molded part

SEM

SEM PBT


No. 2472

Technical Term


Molded Part

Contrast

521

Fracture area

Housing

AL

Resin

PA6.6-GF25

2473

••are harmless in the granulate

518

PC

Extrusion

2474

••below the sink mark

517

PE


AL

2475

••in AMMA

522

AMMA

Thin section

DL

Bracket

Glossary

••and tougher flow of the molding compound due to glass fibers

AL

2476

••in PA/PTFE

076

PA/PTFE

Thin section

Piston ring

AL

2477

••in POM

299

POM

Thin section

Housing

DL-POL + 

2478

••in POM

152

POM


AL

2479

••in POM

533

POM


DL-POL

2480

••in the fracture area

527

POM

Thin section

AL

2481

••microvacuoles

375

ASA


SEM

2482

••through a lack of holding pressure 526

PPE


AL

ABS


AL-DIC + 

PUR

Foaming

Mattress

SEM

PA6.6-GF25

Fracture surface

Housing

AL

2483 Vapor deposition:

Definition

2484

209

••with aluminum

2485 Ventilation, insufficient

Definition

2486 Venting (mold venting)

Definition

2487 Vicat temperature

Definition

2488 Victoria blue (coloring agent)

Definition

2489 Vignetting

Definition

2490 Virus filter made from PTFE-foam

374

2491 Viscosity

Definition

2492 Viscosity influence:

Definition

2493

521

••of glass fibers

2494 Viscosity measurement

Definition

2495 Viscosity number VN

Definition

Pipe bracket

2496 Visual awareness region, microscopic Definition 2497 Visual examination

Definition

2498 Voltage punctures: with “punch channel”

081

PE

Extrusion

Gas pipe

AL

2499

080

PP

Compression molding

Membrane

AL

••at up to 40,000 Volts

2500 Volume shrinkage

Definition

2501 V-shaped inward movement of the seam

083

PE


Diesel can

AL

2502 Wall thickness distribution of a back- 431 molded PC-film

PC

Polished sample


AL

2503 Warm/cool streaks

101

PA


DL-POL + 

2504 Warp film: with hole or stab injury?

557

LDPE

Blown film

Stretch film

AL

2505

558

LDPE

Blown film

Stretch film

AL

ABS



2506 Warp(s)

Definition

2507 Warpage (LM subchapter)

568–573

2508 Warpage:

Definition

2509

570

••for ABS

AL: 1 : 1

69


Glossary

No.

Technical Term


Molded Part

Contrast

2510

••through molded part stress

571

ABS


AL: 1 : 1

2511

••with bulging

569

PBT T40


AL: 1 : 1

2512

••with deflection (uneven tempering) 568

PBT T40


AL: 1 : 1

2513 Warps (SEM subchapter)

327–327

SEM

2514 Water contamination

298

HDPE

Extrusion

Water pipe

AL

2515 Weakening of the cross-section: through charcoal particles

279

PA

Compression molding

Piston ring

DL-POL + 

Tray

2516

••through blowholes

227

ABS

Vacuum forming

2517

••through a vacuole

531

PBTB


AL

2518 Wear, plastic

381

PA6.6


SEM

2519 Weathering (LM subchapter)

006–027

2520 Weathering (SEM subchapter)

307–311

2521 Weathering, artificial, of:

Definition 2

AL

SEM

2522

••EPDM up to 8000 MJ/m (4074 h) 013

EPDM

Extrusion

Gasket profile

AL

2523

••EPDM up to 8000 MJ/m2 (4074 h) 021

EPDM

Extrusion

Window seal

AL

EPDM

Extrusion

Window seal

AL

Facing tile

SEM

2

2524

••EPDM up to 8000 MJ/m (4074 h) 022

2525

••facing tile with crystals

311

Cement bonding

Compression molding

2526

••PA/PTFE up to 15000 MJ/m2

007

PA/PTFE


2

2527

••PC up to 1964 MJ/m (1000 h)

017

PC


DL

2528

••PC up to 3927 MJ/m2 (2000 h)

016

PC


DL-DIC

2529

••PP-UV up to stable 4800 MJ/m (2444 h)

2

307

PP-UV stable


SEM

2530

••PUR up to 8000 MJ/m2 (4074 h)

025

2531

PUR

Casting

Spoiler

AL-DF

2

PVC-U

Extrusion

Window profile

AL

2

••PVC-U up to 8000 MJ/m (4074 h) 008

2532

••PVC-U up to 8000 MJ/m (4074 h) 009

PVC-U

Extrusion

Window profile

AL

2533

••PVC-U up to 8000 MJ/m2 (4074 h) 010

PVC-U

Extrusion

Window profile

AL

UP-GF

Compression molding

Sheet

AL + DL

2534

2

••UP-GF up to 9818 MJ/m (5000 h) 011

2535 Weathering data

307

PP-UV stable


SEM

2536 Weathering warranty, insufficient

308

PP-UV stable


SEM

2537 Webs (floating burr, plastic burr):

Definition

2538

578

PPS


AL

••at the ejector

2539 Weight change

Definition

2540 Weld line:

Definition

2541

••circular

032

POM


AL

2542


274

PA6.6

Electroplating

AL

Clamp

2543

••cold flow, similar to weld line

143

PE

Injection molding Pipe reducer

AL

2544

••cold flow, similar to weld line

157

SAN


AL

2545

••in PS

155

PS

Injection molding Rocker key

AL AL

2546

••lines

028

ABS


2547

••lines

140

PE

Injection molding Spraying nozzle DL-POL

70


No.

Technical Term

Molded Part

Contrast

••lines

399

C-PVC

Extrusion

Fitting

AL

2549

••lines, close to the sprue

030

SB


AL

2550

••not visible in normal transmitted light

141

PE


DL

2551

••open

031

POM


AL

2552

••visible in polarized transmitted light

140

PE


DL-POL

2553

••with axial crack

252

PP


2554

••Y-weld line

029

CA


AL

2555

••Y-weld line

159

PA4.11


AL: 1 : 1

2556

••Y-weld line

160

PA4.11


DL-POL

PA4.11


DL-POL

POM

Injection molding Web ring

AL

Glossary


2548

2557 Weld line (LM subchapter)

028–035

2558 Weld line area with parabolic cold flow lines

160

2559 Weld line number

Definition

2560 Weld line strength

Definition

2561 Weld line, unavoidable

032

2562 Welding (LM subchapter):

461–484

2563 Welding: inclined

464

PB

Socket welding

T-joint

AL: 1 : 1

2564

••of a winding pipe location

439

PE

Filament winding

Laminated pipe

DL-POL + 

2565

••with unequal MFR value

471

PP

Polished sample

Filter

AL

2566 Welding aids

Definition

2567 Welding axis, not in alignment

474

PE

Polished sample

Water pipe

AL

2568 Welding bead comparison: good

463

PP

Polished sample

Pressure membrane

AL

2569

462

PP

Heated tool welding

Pressure membrane

AL

2570 Welding bead: with distinct shear zones

470

PP100

Thin section

Water pipe

DL-POL + 

2571

481

POM

Ultrasonic welding

Molded part

DL-POL + 

471

PP

Polished sample

Filter

AL

••poor

••with lower seam strength

2572 Welding beads: alike 2573

••unequal

477

PVC

Thin section

Window

AL

2574

••unequal

478

PP

Ultrasonic welding

Float

AL

2575

••with good strength of the welded seam

482

POM

Ultrasonic welding

Molded part

DL-POL + 

2576

••with good welding parameters

483

PE

Heated tool welding

Pressure pipe

AL

2577

••with one-sided withdrawal

479

PP

Thin section

Float

DL-POL

2578

••with welding stress

480

PE100

Block ground sample

Water pipe

AL

2579 Welding error

Definition

2580 Welding factor 1: for a PE heating element welding seam

483

PE

Heated tool welding

Pressure pipe

AL

2581

472

PP

Thin section

Container

DL

••a PP-V-notch

71


Glossary

No.


Molded Part

Contrast

2582 Welding influences in an ultrasonic welding seam

Technical Term

479

PP

Thin section

Float

DL-POL

2583 Welding lines

079

PVC/Acryl

Polished sample

Window profile

AL-DIC

2584 Welding parameter

481

POM

Ultrasonic welding

Molded part

DL-POL + 

2585 Welding pressure in electro fusion welding

474

PE

Polished sample

Water pipe

AL

2586 Welding seam: wider than the sum of the individual films

074

PE

Thin section

Blown film

DL-POL

2587

••examine

Definition

2588

••insertion depth

475

PB

Polished sample

Sleeve

AL

079

2589

••of a window profile seam

2590

••rule: a minimum of 10–20% of the 480 wall thickness

2591

••seam comparison (good and bad seam)

2592

••seam contour (electro fusion sockets weld line)

PVC/Acryl

Polished sample

Window profile

AL-DIC

PE100

Block ground sample

Weld line

AL

477

PVC

Heated tool welding

Window

AL

475

PB

Polished sample

Sleeve

AL

2593

••seam influences

477

PVC

Thin section

Window

AL

2594

••seam width of a blow film

073

PE

Thin section

Blown film

DL-POL

2595

••thicker seams

074

PE

Heated tool welding

Blown film

DL-POL

2596

••V-notch with cooling zones

472

PP

Fan welding

Container

DL

2597

••weld line, microscopic

479

PP

Imbedding EP

Float

DL-POL

2598

••with carbon black streaks

469

PE

Thin section

Sheet

DL

2599

••with shearing zone

056

PA

Rotational molding

Oil tank

DL-POL + 

2600 Welding stresses in a polymer welding line

309

Polymer

Extrusion

Bituminous sheeting

SEM

2601 Wet sanding paper, graining

517

PE

Block ground sample

Handle

AL

2602 Wettability:

Definition

2603

••of ABS

250

ABS

Injection molding Connector for partition walls

AL: 1 : 1

2604

••reduced

211

PA6-GF30/PE


AL

2605 Wetting agent test:

Definition

2606

••created media cracks

236

SAN

Injection molding Filter cup

AL: 1 : 1

2607

••for ABS/PC

488

ABS/PC


AL

2608

••for PC with toluene-propanol 1 : 3

065

PC

Vacuum forming

2609

••for PC with toluene-propanol 1 : 3

496

PC


AL

2610

••for SAN

485

SAN


DL-POL

Sky light

AL

2611 Wetting agents:

Definition

2612

••cracks in the pinpoint gating

488

ABS/PC


AL

2613 Wetting defects on part surface

168

POM


AL

2614 Wetting test:

Definition

72


No. 2615

Technical Term ••with test pins


Molded Part

Contrast

Injection molding Connector for partition walls

AL: 1 : 1

2616 Wollaston prism:

Definition

2617

••example of an application for PA6.6-GF30

115

PA6.6-GF30

Thin ground sample

Cover

DL-POL + DIC

2618 Wood fibers as a reinforcement material (WPC)

196

WPC

Extrusion

Profile

AL: 1 : 1

2619 WPC-plastics:

Definition

2620

196

WPC

Extrusion

Profile

AL: 1 : 1

2621 Y-crack

401

PVC-U

Extrusion

Pipe

AL

2622 Yellowing of PVC

Definition

2623 Zinc layer, thickness measurement after etching: with nitric acid

441

Zn

Etching

Cast sleeve

DF-AL

2624

442

Zn

Etching

Cast sleeve

DF-AL

••example: extrusion profile

••with acetic acid

73

Glossary

ABS

Chapter 2 Definition of Terms in the Technical Glossary This chapter contains, in alphabetical order, explanations of the technical terms (definitions) in the Technical Glossary with links (arrows) to related quality and damage causes, manufacturing processes, and microscopy accompanying studies. If a technical term cannot be found in this chapter, then the search can be continued in the Technical Glossary (Chapter 1). Learners will also find unknown technical terms, and thus a quick introduction to the subject through “→ novice terms” and “→ microscopic examination” in this chapter. These terms are the source of the network with arrows through the entire encyclopedia. This chapter is especially suited for learning. It also contains brief description of key manufacturing processes and microscopy accompanying studies. Using the technical terms and the corresponding figure numbers from the Technical Glossary, the associated figures can be found in the Chapter Quality and Damage Figures (Chapter 3). In an examination, experts quickly recognize the technical word that is relevant to the distinctive feature and thus find it in the Technical Glossary, and from the given figure number the associated figure with figure caption in the Chapter Quality and Damage Figures, and, if desired, an explanation of the technical word in the Chapter Definitions. Color coding

Explanation

Thumb Index

Technical terms, arranged alphabetically in the Technical Glossary

Glossary

Figure numbers from 1 to 588, arranged in the Chapter Quality and Damage Figures

Figures & Text

LM subchapter with figure captions in the Chapter Quality and Damage Figures

Figures & Text

SEM subchapter with figure captions in the Chapter Quality and Damage Figures

Figures & Text

Explanation of the technical terms from the Technical Glossary in the Chapter Definitions

Definitions

LM = Light microscopy (or light microscope) SEM = Scanning electron microscopy (or scanning electron microscope)

For search examples, see pages X–XII. Novice terms are words for striking features of a sample that the student can see directly (visually) or under the microscope. There are external and internal striking features. Internal striking features are examined, for example, in a thin section or a fracture surface. The following table connects colloquial, novice words with the corresponding technical terms. In the technical terms glossary, the corresponding quality or damage image can be found through the figure number, and more explanations can be found in chapter definitions.

75

Definitions

Definition of Terms in the Technical Glossary

Novice Terms

Place

Technical Terms e = external and i = internal striking features

Abrasion

e

Damages, mechanical

Appearance, old

e

Aging

Back injection

i

Fig. 430

Bead

e

Welding bead comparison, welding bead

Bonding

e

Bonding, residue

Brittleness

i

Fracture, embrittlement

Break

I

Fracture, fracture types, fractures, cracks, embrittlement

Browning

e/i

Diesel effect, overheating

Bubble(s)

e

Bubble, bubble formation, mold venting

Burning

e/i

Burning, burn streak, decomposition, thermal

Cavity

i

Blowhole, vacuole

Chatter marks

e

Slip-stick effect

Chemical attack

e/i

Resistance to chemicals, media attack

Coating

e

Coating, laminating, surface refining

Color changes

e

Aging, color change, surface discoloration

Color streaks

e

Color streaks, streaks

Contrast

e

Illumination, contrast, contrast processes in microscopy

Crack

i

Cracks, fractures, types of fractures, media that can cause stress cracking

Cut

e/i

Thin section, cutting, cutting injury, scalpel cut

Damage

e

Surface error, damages, mechanical

Deflection

e

Shrinkage, post-crystallization, plastic deformation, tempering, warpage

Deformation

e/i

Deformation, post-crystallization, plastic deformation, warpage

Dent

e

Dent, notch, surface error, groove, damages, mechanical

Deposition

e

Particle, residue

Deposits of grease

e

Wettability, residue

Dimensional error

i

Deformation, free-fall demolding, design error, dimensional error, warpage

Discoloration

e

Aging, color change, migration, surface discoloration, overheating

Displacement

e

Delamination, painting error, surface error, layer displacement

Dissolving

e

Dissolving

Dots, also dark spots

e/i

Particle, pigment conglomerate, carbon black pigments

Edge, sharp

e

Burr formation, web, burr

Embrittlement

i

Aging, moisture influence, media attack, embrittlement, predrying

Error

e/i

Surface error, error, human, rheological and systematic

Fading

e

Efflorescence, fading

Filament

e/i

Gate filament, fibrils

Flow direction, different

i

Reversal of the flow front, mass inversion

Flow front

i

Reversal of the flow front, mass inversion, cold flow front, cold flow area

Fracture

e

Aging, artifact, cracks, embrittlement

Furrows

e

Gate grooves, cold flow lines

Gate filament (string)

e

Gate, runner

Glass fibers

i

Glass fiber length distribution, glass fiber breakage

Gloss change

e

Gloss measurement, spots

Gold plating

e

Sputtering, scanning electron microscopy

Goose bumps

e

Orange skin, cold flow, surface error

76


Novice Terms

Place

Technical Terms e = external and i = internal striking features

Graining

e

Orange skin

Granulate contamination e/i

Granulate contamination

Grip

e

Haptic, surface refining

Groove

e

Groove, surface error

Hole

e/i

Sprue, gate, blowhole, vacuole

Image resolution

e

Resolution, illumination, image resolution, contrast

e

Coating, laminating, surface refining, layer formation

Lines, bright

e/i

Streaks, homogenization, microcracks

Lines, colored

i

Isochromatics, polarization optics

Lines, dark

i

Spherulite streaks, pigment streaks, carbon black streaks

Lines, mechanical

e

Coldflow line, scratch, surface error, polishing, groove, grinding

Marking

e

Ejector mark, surface error

Material change

i

Masterbatch change

Matte spot

e

Moisture, moisture streaks, shape stains, matte spots

Metallized surface

e

Electroplating

Mold change

e

Deformation, dimensional change, shrinkage, tempering, warpage

Notch

e

Notch, surface error, groove

Over-injection

e

Weight change, material residue transfer, particle, over-injection

Particle

e/i

Particle, pigment conglomerate, carbon black pigments, over-injection

Pressure point

e

Dent, surface error, damages, mechanical

Record groove

e

Gate grooves, cold flow lines

Roughness

e

Orange skin, cold flow, surface error

Scratch

e

Scratch, groove, cold flow line, surface error, polishing, grinding

Sensitivity to fracture

i

Aging, moisture influence, notch, media attack, embrittlement

Shaping

e

Molded part quality, mold impression, mold filling

Shrinkage

i

Shrinkage, volume shrinkage

Shrinking

i

Shrinkage, post-crystallization, plastic deformation, tempering, warpage

Sink marks

e

Weld line, sink mark, shrinkage

Solution

e

Dissolving

Spots

e

Orange skin

Stains

e

Shape stains, matte spots, media streaks, surface error, residue

Streaks

e/i

Streaks, hot-cold streaks, pigment streaks, thermal streaks, burn streaks, surface discoloration

Strips

e

Strips, streaks, black streaks, pigment streaks, surface discoloration

Surface error

e

Surface error

Swirls of color

i

Large and small spherulites, inversion layers

Thin ground sample

e/i

Thin ground sample, thin grinding device

Thin section

e/i

Thin section, thin section device (microtome)

Thorough mixing

i

Homogenization

Tip

e/i

Fibrils, stretching tip (Fig. 46)

Track

e

Surface error, grinding, damages, mechanical

Warp

e

Cold flow line, cold flow, paint warp, streaks

Waves

i

Fig. 458, grooves, tear (Fig. 322), bead

Weathering

e

Weathering, artificial

Wetting

e

Wettability, wetting test, test pins, test ink

Definitions

Layer displacement

77

Definitions


Abrasion

Technical Terms


Abrasion

Abrasion is surface wear, for example due to reinforcing materials in the screw and in the cylinder (see also → glass fibers).

Achromatic lens

In an achromatic lens, the objective is corrected in the two colors, red and blue, so that both will be reflected in the focal plane without distortion (see also → Neofluar lenses, → objective, and → plan apochromatic objective).

Additive

Additives are added to plastics to improve their properties and service life (aging). Additives include antioxidants (inhibitors, light stabilizers, fire protection equipment, radiation protection, UV stabilizers, heat stabilizers), filler materials (nanofillers, glass fibers, kaolin, chalk, magnesia, sand), lubricants, and nucleating or reinforcing materials (see also → antioxidants, → fire prevention equipment, → filler materials and reinforcing materials, → GC analysis, → glass fibers, → lubricants, → HPLC analysis, → inhibitors, → IR analysis, → analysis of plastic materials, → light stabilizers, → nanofillers, → nucleating agents, → radiation protection, → UV spectroscopy, → UV stabilizers, → reinforcing materials, and → heat stabilizers).

Adhesion

Diffusion-based acrylic adhesives have particularly proven their worth for adhesion of thin ground samples onto glass slides. Depending on the sample hardness and requirements, EP and UP resins with and without filler materials are also used. A sample glued with a diffusion-based acrylic adhesive can be carefully removed with a preparation needle from the glass slide after 10 minutes immersion in ethanol. Many plastics have adequate resistance. Then the exposed thin ground sample is fixed onto a glass slide with Canada balsam or Eukitt and is covered with a cover glass. This is how clean thin ground samples can be manufactured in thin section quality, without air bubbles, peeling places, and coolant back migration (see also → thin grinding device and → adhesive bonding).

Adhesion testing for paint

→ Microscopic examination

Adhesive bonding

Adhesive bonding is the bonding of similar or dissimilar joining partners with crosslinking or solvent-containing adhesives, with or without filler material content. Thin sections are bonded onto glass slides with Canada balsam or Eukitt and protected with a cover glass. For thin sections, the abrasive samples are bonded onto glass slides with two-component adhesives on an EP-/UP- and acrylic-base or one-component cyanoacrylate adhesive and are then ground. If thin section samples are difficult to handle, are sensitive, and have multiple edges, they are still bonded onto glass slides with the above-mentioned adhesives and are cut afterwards. One- or two-component adhesives can be used (see also → adhesion, thin ground sample, → thin section, → glass slide, → Canada balsam, → polishing, → preparation techniques, and → grinding).

Adhesive tape test

The adhesion of paints and film coatings is measured with the adhesive tape test (also adhesive tape method). For example, an adhesive tape is rubbed free of air onto the paint layer and is then suddenly torn off perpendicular to the surface. The more paint particles adhere, the worse the adhesion strength.

After-treatment

→ Pre- and post-treatment

Agglomeration

Agglomeration is a secretion of microparticles by efflorescence and chalking of ingredients (see also → efflorescence).

Aging

Aging is a degradation, destruction, or discoloration of the matrix (matrix degradation) or molding surface by additives, agglomeration, aging causes, segregation, color change (molded part), moisture, molded part stresses, hydrolysis, inhomogeneities, media influences (ozone, acids, alkalis, cracking under stress, swelling), migration, holding pressure error, post-crystallization, post-shrinkage, surface defects (porosity, paint influence, color and gloss changes), orientational stresses, oxidation, polymerization, relaxation, stress corrosion cracking, ultraviolet or ionizing radiation (-, -, and -rays), and alternating temperatures. The higher the temperature, the faster a plastic ages. Changing temperatures cause faster aging by stretching and shrinkage stresses. Chemical, thermal, and or physical-mechanical tests are carried out to test the aging resistance, often mixed as accelerated aging tests (media, causing cracking under stress, cooking test, weathering, MFR analysis, VZ analysis, heat exposure as well as tensile, pressure, and bending tests, etc.). Additional factors are the type of plastic and quality, the mechanical load, the miscibility of the additives, and microbes (see also → additives, → agglomeration, → aging resistance, → aging influences, → aging protection, → causes of aging, → weathering, artificial, → segregation, → color change (molded part), → moisture, → molded part stresses, → hydrolysis, → inhomogeneities, → cooking test, → media, causing cracking under stress, → media influence, → MFR analysis,

78

Aperture, numerical


Technical Terms


Aging

→ migration, → holding pressure error, → post-crystallization, → post-shrinkage, → surface defects, → orientation stresses, → oxidation, → polymerization, → relaxation, → stress corrosion cracking, → ultraviolet UV radiation, → UV stabilizers, → viscosity number, → pre- and post-treatment, → heat exposure, → changing temperatures).

(continued)

An air inclusion is formed in a mold with insufficient ventilation because the air cannot escape fast enough when injecting the molding compound. Air inclusions are also possible during welding when the joint partners have a strong topography and the welding parameters (temperature, pressure, and time) are not sufficient (see also → air streaks and topography).

Air streaks

Air streaks (air inclusions) are caused in the mold by entrained air during injection molding of poorly degassed molding compound, insufficient nozzle position, and a knocked-out bushing or nozzle (see also → air inclusion).

Analysis of plastic materials

Plastics, its additives, and its properties can be determined for example with the following tests: → density determination, → DMA analysis, → DSC analysis, → ESCA analysis, → FTIR analysis, → determine fillers and reinforcing materials, → GC analysis, → glass transition temperature range, → GPC analysis, → gravimetry (weight determination), → HPLC analysis, → IR analysis, → MFR analysis, → molecular weight is determined, → monomers, → MVR analysis, → ODSC analysis, → oxidation stability, → determine polymer blends, → measure residues, → TG analysis, → thermogravimetry, TG, → TMA analysis, → UV spectroscopy, → Vicat temperature, → viscosity measurement, → viscosity number, → determine thermal stability, and → determine plasticizer.

Analyzer

→ Polarizer, → universal microscope, → Wollaston prism

Angle of inclination j → Knife angle Antioxidants

Antioxidants are antiaging agents (antiozonant and antioxidant) to protect the plastic from oxygen and ozone attack. Antioxidants delay aging (see DIN 50035-1) in the manufacture and application of plastic. Antioxidants are inhibitors, light stabilizers, radiation protection, UV stabilizers, and heat stabilizers (see also → aging and → causes of aging, → inhibitors, → light stabilizers, → radiation protection, → UV stabilizers, and → heat stabilizers).

Aperture

The aperture (opening) should be large enough that the rays of light entering the objective will give a bright, sharp picture. In transmitted light, the light through the particles (e.g., pigments, spherulites) is refracted and diffracted in a thin section or thin ground sample. The smaller the particles are, the greater the light is refracted. A condenser is used so that no light is lost. It has the same aperture as the objective. A further improvement of the aperture is achieved by immersion oils. They have a refractive index of n = 1.51 (like glass). These oils reduce the reflection of light at the boundary layers of glass slide/cover glass/air/objective, and the light behaves as if all the boundary layers are made of glass. The numerical aperture NA grows with the objective and condenser aperture; a high refractive index (immersion optics); the cleanliness of the slide, objective, and cover glass; the correct cover glass thickness (0.15 mm); “Köhler illumination;” decreasing light wavelength  (e.g., blue light); and the magnification of the objective number VOB (see also → aperture, numerical, → aperture diaphragm, → image resolution, → resolution, microscopic, → refractive index, → Köhler illumination, → condenser, → microscope, and → lens).

Aperture angle

→ Aperture, numerical

Aperture diaphragm

The aperture diaphragm in the pupil’s optical path controls the resolution, contrast, and depth of field. It is not visible in the picture, only its effect. While it affects the brightness, it is not responsible for it. When dimmed, the diffraction (diffraction margin) increases and thus the image quality decreases. The adjustment of the aperture to the objective aperture is done through the aperture diaphragm. In reflected light, the following order applies: lamp – aperture – field diaphragm, and in transmitted light: light – field diaphragm – aperture diaphragm. The aperture diaphragm should only be closed to about one-third; otherwise the image quality drops due to diffraction margins and image dimming. But it is only closed until the best or desired image contrast is achieved (see also → hatch optical path, and → optical path of the pupil).

Aperture, numerical

The numerical aperture NA = n · sin  ( = aperture, n = refractive index, nair = 1). An objective comparison is achieved via the numerical aperture NA. Theoretically NA reaches the value 1 in air, which corresponds to an opening angle of 180°. The maximum angle is 142°, that is, the numerical aperture reaches a maximum of 0.95. The magnification numbers and NA, such as 20x/0.5, are given on the objectives. The highest resolution achieved is the currently strongest immersion optic of 40x/1.4 i.

79

Definitions

Air inclusion

Definitions


Appraiser qualities

Technical Terms


Appraiser qualities


Artifact

An artifact is an outbreak in the molded part surface.

Audit

→ Report and → report preparation, fast and competent

Axial crack in the inner surface of a pipe

The outside surface of heating pipes is compressed during calibration and is rapidly frozen with compressive stresses in the water bath, while the uncooled, warmer inner surface of the pipe further shrinks under tensile stresses. With hot water use, or in 150 °C heat exposure, the stress decrease between the outer pipe and the inner pipe surface and the resulting decrease in compression stresses enlarge the outside diameter of the pipe again and the “tempered” inner diameter of the pipe (spring back). Therefore, axial cracks sometimes only develop in the inner surface of the pipe, without a connection to the outside (see Fig. 403, → heat exposure, and → water bath).

Azo crosslinking

→ Plastics, crosslinked

Back injection

Back injection occurs when, for example, a film preformed in a vacuum process is placed into an injection mold and back-injected with polyamide for reinforcement, or if an elastic material is injected or back-injected to the molded part on a following shot (see also Fig. 430 and → following shot).

Barrier layer

→ Diffusion barrier

Beam splitter (blocking filter)

In an incident light microscope, a beam splitter is used to guide the bulb light to the sample. From there it passes through the beam splitter (reflective) and passes into the ocular. In fluorescence contrast, a part of the blue excitation light is reflected from the beam splitter onto the sample, and the other part passes through the beam splitter to the ocular as green excitation light with changed wavelength  (Stokes shift). Thereby a barrier filter filters out blue components (UV components), and the fluorescent image glows green against a black background image (see also → contrast processes in microscopy).

Beilby layer

→ Polishing

Black streaks

→ Overheating, thermal

Blackening

Blackening occurs through a burning of the molding compound (diesel effect) or in PVC window profiles through the reaction of lead or cadmium with sulfides to form black lead sulfide or cadmium sulfide, respectively (see also → diesel effect, → surface discoloration, and → red coloration of PVC).

Block ground sample A block ground sample is formed by hand-grinding a sample and is also that what remains in the grinding machine when a thin ground sample is produced. After removal of the sample, it is usually only ground (ground sample) on one side with a grain size 320, 500, 800, and 1200 (grain size 15 microns), and then directly analyzed in the light microscope. The block ground sample shows the orientation and distribution of the fillers and reinforcing materials after a short preparation time. Should, after grinding, polishing be done with alumina Al2O3 (grain size of 1 micron), the less frequently used wet grit paper with a graining of 4000 (grain size 5 micron) reduces the grain-jump from 5 microns to only 1 micron, instead of 15 microns to 1 micron. Typical grain sizes of alumina are 0.25, 0.5, and 1 micron (see also → thin grinding device, → orientation, and → grinding). Block section

A block section is the remaining specimen that is left in the microtome after a thin section is cut. Its surface is smooth, as if polished. PVC integral-rigid foams (KG pipes with PVC rigid foam between the inner and outer layer) can be cut very well and are thus much quicker to manufacture than with a polished sample (see also → thin section, → thin section device (microtome), and → polished sample).

Blocking filter

→ Beam splitter

Blow molding

The blow molding of hollow bodies (bottles with a threaded neck) is performed on an injection molding machine in a special mold. For example, PET bottles are produced in a two-stage process. First, a preform is injected into a 5 to 8 °C warm mold half. It is then inserted into the mold blow half after rewarming to 90 to 120 °C and is there inflated by a blast of compressed air to form the bottle and is ejected after cooling. The wall thickness of the preform is 4 mm (see also → Fig. 48, → extrusion blow molding, → injection molding, and → rotational molding).

Blow molding of hollow objects

During blow molding of hollow objects, a pipe is extruded from the extruder, guided into a shaping opened mold through an angle head, inflated with compressed air after closing, and demolded as a hollow body (molded part) (see also → film blowing, → blow molding, → extrusion, → injection, and → rotational molding).

Blowhole

→ Vacuoles and blowholes

80

Cavity



Bright field contrast AL-HF and DL-HF

The bright-field contrast AL-HF is the simplest microscopic contrast process with normal incident light (without lambda plate or polarizer). The bright field contrast is suitable for transmitted or not-transmitted samples and the bright-field contrast DL-HF only for transmitted samples (see also → thin section, → contrast processes in microscopy).

Bubble

→ Bubble formation

Bubble formation

Fine bubbles in the molded part surface are caused by high residual moisture. Therefore, a plastic granulate is basically predried in drying devices (e.g., 4 h at 60 to 80 °C). In addition, a degassing screw may be useful (see also → electroplating error, → painting error, → residual moisture, and → predrying).

Burn streak(s)

Burn streaks are brown streaks or black streaks. They develop through overheating or thermal decomposition (see also → brown streaks, → black streaks, and → overheating).

Burr formation

A burr formation (web or burr) is created during the mold separation by mold breathing, on ejectors (through wear) and areas of ventilation, particularly for easily flowing molding compound, at high injection and holding pressures, insufficient clamping force, slow-moving molding compound, and high pressure or high mass temperature (see also → holding pressure).

Calendering

Calendering is the manufacture of smooth and embossed films of a high surface quality on a large roller system. Calendered films have more precise wall thicknesses than extruded and blown films.

Camera switch

The camera switch switches the amount of light from the ocular to the image camera in a universal microscope (Fig. 105).

Canada balsam

Canada balsam and Eukitt are embedding agents. They are used for the adhesion of thin sections and to improve the contrast, because their refractive index corresponds to the one of glass (microscope slides and cover glass). Canada balsam contains toluene, dries very slowly, and can be thinned with alcohol. Eukitt dries very quickly (even in the bottle) and has an unpleasant odor. A fresh thin section can still be examined immediately (see also → diffusion adhesive, → thin grinding device, → thin section, → embedding media, and Fig. 103). Source: Merck Eurolap (Laboratory supplies, microtomes, slide, Canada balsam, Tel: +49 911/64208040).

Carbon black streaks

Carbon black streaks are black pigment streaks. They develop with subsequent coloring and lack of homogenization (see also → coloring, → homogenization, → masterbatch, and → decomposition, thermal).

Cause of cracking

Possible crack causes are molded part stresses in production (injection molding, extrusion, etc.), high screw tightening torque, design error, media attack, mechanical stress during use, UV and radioactive radiation, processing forces (drilling, thread cutting), embrittlement, alternating pressures, alternating loads, changing temperatures (see also → aging, → extrusion, → molded part stresses, → design error, → media attack, → sample preparation, machining, → cracks, → redirecting the crack, → injection molding, → embrittlement, and → changing temperatures).

Causes of aging

Aging causes are agglomeration (efflorescence of additives), limited miscibility of individual additives to the plastic, residual stress (caused by uneven cooling and density distribution, often leading to stress cracks), poor homogenization of additives, mechanical stress (fatigue cracks), media influences (oil, solvents, and wetting agents, ozone, acids and alkalis, autocatalytic oxidation (O2), and hydrolysis by H2O), migration of additives or plasticizers, microbes, post-crystallization, post-shrinkage, orientation stresses (through macromolecule orientations generating stress cracks), temperature change, incomplete polymerization, addition and condensation, embrittlement, heat, and ultraviolet or ionizing radiation. Stress corrosion arises when corrosion and stress are interacting. Other causes: see also → additives, → aging, → aging resistance, → aging influences, → aging protection, → antioxidants, → efflorescence, → vaporizing, → coating protects from light, UV, and media influence, → electroplating, → inhibitors, → painting, → light stabilizers, → quality influences during extrusion, → quality influences during injection molding, → radiation protection, → tempering, → heat stabilizers, → heat exposure).

Causes of fracture

See also → embrittlement and influences, → holding pressure, → hold pressure, → holding pressure error, → lack of holding pressure, → pigment streaks, → relaxation, → tempering, and → heat exposure.

Cavitation

Cavitation generates erosion and cavity formation, simply by a flow of liquid or in conjunction with foreign objects, such as sand in PVC water pipes (see also Fig. 559).

Cavity

The mold cavity is a formed hollow chamber in the mold. A mold can have many cavities, spread across different levels (stack mold), to get higher quantities or time. In the molded parts, the mold cavity numbers are already embossed into the mold. Thereby a defective molded part can be assigned to the cavity in which it was prepared by the cavity number. This is also important, for example, for a filling study.

81

Definitions

Technical Terms

Definitions


Center vacuole

Technical Terms


Center vacuole

A center vacuole usually occurs in thick-walled, symmetrical molded parts. The core remains plastic longer and the plastic volume has more time to disappear in large wall thicknesses. The vacuoles become particularly large at a too-short holding time in the center of large-volume cross-sections (see also → shrinkage, → core, plastic, and → holding pressure time).

Certificate, testing

→ Test certificate

Chalk in PVC-U

Chalk is a filling and processing aid (see also Fig. 337). The chalk content in plastics (e.g., PVC-U) is calculated stoichiometrically from the sulfated ash content with ≅ 1.36 × chalk content% (SKZ formula; see also → filler materials and reinforcing materials testing).

Changing temperatures

Changing temperatures are rapidly varying temperatures in use or periodically created temperature changes in laboratory studies to determine the aging resistance of, for example, water pipes. Long-lasting, rapidly changing temperatures shorten service life through structure degradation (see also → aging, → aging resistance, → matrix degradation, → service life, and → temperature influence).

Chemical baths

In chemical baths, an increase in the → wettability occurs through an O2 involvement.

Clamping block method (Measuring the film layer thicknesses)

With the clamping block method, layer thicknesses for multilayer films are examined much faster than after embedding in epoxy resin EP or by thin section. Between two PVC clamping blocks (see also Fig. 96), equally sized film cuts are inserted into both clamping sides so they remain parallel when tightening the brass screws. Both excess films are cut off (dragging diagonally) with a scalpel, flush with the PVC surface. Thereby, the developing cut grooves are located diagonally to the individual layers and do not simulate more layers than available. The scalpel cut is then measured microscopically. Caution: a thin section is suitable to identify the layers, but never shows the exact layer thickness due to an unavoidable transverse contraction like a scalpel or block section (sample residue between the clamping blocks or in the microtome).

Clamping force

→ Mold clamping force

Cleaning agent influence

Release agent residues on the molded parts should be washed thoroughly with suitable cleaning agents, even against manufacturer’s instructions. Influences can be seen under → fading, → solvent evaporation, → delamination, → release agents, → color change, → electroplating error, → thread overload, → painting error, → surface discoloration, → preparation agents, → release agent, and → packaging and transportation.

Clouding

When clouding on the molding surface occurs, the following processing parameters are too low: → injection rate (injection pressure), bulk temperature, or → mold temperature.

Coating

Plastic surfaces are coated to beautify and to improve the feel, aging, sliding properties, and abrasion. The coating also protects against light, UV, and media influences (see also → haptics and → surface refining).

Cold embedding

→ Embedding

Cold flow

Cold flow is the generic term for cold flow areas and cold flow errors due to a reduced molding compound flow. Cold flow is, to our knowledge, one of the most common causes for damage. It is created during injection molding through cold processing and too-slow mold filling due to a low injection rate, molding compound temperature, narrow pinpoint gate, poor mold venting, defect jacket heating, high molding compound viscosity (filler and reinforcing materials, type of plastic), roughness of the flow path (polish sprue/gate, nozzle, and channels), core flowing, metal inserts (insert, without preheating), mold temperature, long flow paths, very thin flow cross-sections, and wall thickness as well as film hinges. See also → weld line with V-shaped collection of the surface and structures, which are similar to the weld line, → delamination (only through hot-cold streaks), → sink mark, → error, rheological, → molding compound, frozen, → inversion layers, → cold flow area, → cold flow front, → cold flow lines (record grooves), → cold plugs (cold particle), → flaking, → surface, tortured, → orange skin, → mold filling, poor (see also → extrusion, → error, rheological, → reversal of the flow front, → mass inversion, and → injection molding).

Cold flow area(s)

→ Cold flow

Cold flow errors

→ Cold flow

Cold flow line(s)

A cold flow line is a warp in the molded part surface (see also → cold flow).

Cold particles

→ Cold plug, → particle

82

Conditioning



Cold plug

A cold plug (flaking) is a cooled molding compound particle, for example from a “dead corner,” which is often washed onto the molded part surface close to the sprue (material residue transfer). It also develops when the jacket heating of the nozzle seat is defective – was applied poorly or too far away – and thereby the nozzle heating is not sufficient or effective, or if the nozzle bore hole is too small. Another cause could be a too-old sprue bushing (see also → material residue transfer, → cold plug, → particle, and → dead corners in the mold).

Cold treatment in thin sections

A cold treatment turns soft plastics (elastomers) for thin sections into harder plastics, which can then be cut. A cold spray is not enough because the heat content of the microtome knife is too high in comparison to the developing thin section. This can only be done with a cryostat system.

Collection chamber

→ Injection molding

Color change (molded part)

When changing the color between a good and a defective part, a concealed pigment change, for example through low-cost purchases, must be considered. Other influences include → aging, → aging influences, → aging causes, → weathering, artificial, → masterbatch change, → moisture, → media influence, → surface discoloration, → oxidation, → temperature influence, → ultraviolet radiation (UV radiation), and → pre- and post-treatment.

Color filter

Color filters enhance or weaken the color impression under the microscope. A blue filter lightens and increases the resolution. A polarizing filter or a DIC slider with a lambda plate works like a color filter (see also → resolution, microscopic, → illumination, DIC slider, → lambda plate, and → polarizing filters).

Color measurement

→ Weathering, artificial, → color change

Color pigments reduce the strength

Color pigments should be dosed low. They can disturb the plastic matrix and do no bond with it. They are divisive, especially with increasing content and poor homogenization. And pigment streaks can result in a tensile fracture.

Coloring

Fine cracks and even weld lines and heating regions in conjunction with a hot air treatment become visible through coloring with 3 to 5% fuchsine or Victoria blue. The color pigments are water or alcohol soluble. Fuchsine is a red and Victoria blue is a blue pigment powder. The pigments are stirred into water or better yet into alcohol, if compatible with the plastic, and are applied with a cloth. Any excess should be immediately wiped off. The dispersion penetrates quickly into the smallest cracks with high capillary reaction and makes it more contrasting and more visible. The coloring of noncolored plastics is achieved with a masterbatch or rarely with a liquid color. Pigments basically interfere in the matrix, and can reduce the molded part strength, because they are foreign bodies between the macromolecules and do not connect with them. Therefore, it is recommended to only use an approved masterbatch and to only use as little as possible. An increased tendency to fracture is sometimes observed after a masterbatch change for cost reasons (see also → causes of fracture, → dispersion, → molding compound, primary colored, → molded part strength, → hot air treatment, → homogenization, → contrast processes in microscopy, → masterbatch, → matrix, and → discoloration).

Combine contrast processes

For examination under a microscope, the statement depth of various contrast processes should always be checked. Frequently, seemingly meaningless combinations of polarizing filter, -plates, and DIC sliders will result in unexpectedly good contrasts, which would not be possible with the contrast processes that are recommended (see also → contrast processes in microscopy).

Company’s expert report

→ Report, → report preparation, fast and competent

Compatibilizers

→ WPC plastics

Condenser

The condenser should optimally illuminate the sample and the lens and should be correctly set for every increase in height, axis, and opening. Following the Köhler illumination principle, the light rays that are coming from the field diaphragm are combined in the sample by condensing. From here the imaging is performed together with the sample over the intermediate image plane onto the retina. With proper height adjustment of the condenser, the edge of the field diaphragm along with the sample will appear sharply (see also → resolution, microscopic, → aperture diaphragm, and → Köhler illumination).

Conditioning

Freshly demolded plastic molded parts made of polyamide PA are brittle and break easily. Therefore, they must, for example, be conditioned under water for two hours, so their brittleness (sensitivity to fracture) disappears. The conditioning is unnecessary, for example, for a PA/PE polymer blend because this initial brittleness disappears by adding polyethylene PE.

83

Definitions

Technical Terms

Conglomerate



Conglomerate

→ Pigment conglomerate

Contrast

The contrast grows with the proper contrast process, resolution, and sharpness. The aperture diaphragm has an influence as well. The contrast is zero if the color difference ∆E*ab and the brightness distance ∆L*ab are both zero. A contrast is created if one of these values is greater than zero, even if the other one is zero. For example, on a viewing surface, a contrast is created between two different color values or two brightness values (see also → resolution, microscopic, → aperture diaphragm, and → contrast processes in microscopy).

Contrast processes in microscopy

There are six basic contrast processes in microscopy: DF, DIC, FL, HF, PH, and POL, because no image is created without a contrast! Although the bright field contrast HF (AL and DL) also provides a contrast, it is not included in the literature. The basic contrast processes form a total of 16 contrast processes in the incident and transmitted light with contrast-changing polarizers and lambda plates (with POL and DIC). The contrast processes of microscopy are:

Definitions

Technical Terms

Type of contrast

Incident light

Transmitted Application light

Bright field contrast HF

AL-HF

DL-HF

AL: Transparent and nontransparent samples,

Dark field contrast DF

AL-DF

DL-DF

AL: Pigment colors, surfaces,

DL: transparent samples DF: fine, bright structures

Differential AL-DIC interference contrast DIC

DL-DIC

AL: Topographies, metallized surfaces,

Differential AL-DIC + l interference contrast DIC with lambda

DL-DIC + l

Fluorescence contrast FL

AL-FL

DL-FL

AL: Microcracks visible though fluorescent agents,

Phase contrast PH

AL-PH

DL-PH

AL: Filler material in elastomers,

Polarization contrast POL, not colored

AL-POL

DL-POL

AL: Avoidance of gloss reflections,

Polarization contrast POL, colored

AL-POL + l DL-POL + l

DL: only used for special contrasts (from the author) AL: Topographies, metallized surfaces, DL: only used for special contrasts (from the author)

DL: not necessary (from the author) DL: fine refractive indices Dn DL: spherulites, orientations, and molded part stresses

See also → analyzer, → illumination, → DIC prism, → lambda plate (-plate), → contrast, → microscopic examination, and → polarizer. Convection oven

A convection oven has precise tempering and air circulation so that the entire interior has the same temperature. For example, molded parts are tempered or predried in a convection oven (see also → heat exposure).

Conversion filters

Fig. 105 and → microscope parts

Cooking test

A cooking test is an aging test, for example for paints. Painted molded parts are heated in 90 to 100 °C hot water for several hours (depending on specification) and are then usually visually and microscopically examined for blistering, peeling paint, and color changes in correspondence to given evaluation criteria.

Cooling time

The plastic molding compound is cooled due to the lower temperature in the mold and solidifies. The time required for this is the cooling time (see also → injection molding).

Core displacement

→ Core offset

84

Crystallite melting temperature range



Core offset

A core offset (core displacement, molded part offset) is created by asymmetric gating of a long, not sufficiently rigid mold core or at high injection and/or holding pressures. Here, the mold core escapes sideways due to the flow pressure. A core displacement mostly causes significant differences in wall thickness and hence different strengths, especially close to the sprue because there the injection pressure pushes the core furthest. An offset of the mold separation can cause an offset in the molded part (molded part offset) if the mold guide pins are not well fitted.

Core, plastic

→ Plastic core

Corona treatment

→ Electrostatic surface treatment and → wettability

Correspondence

→ Report preparation, fast and competent

Corrosion

→ Wetting test, → stress crack corrosion, → media attack

Cost factors

→ Influences on quality and costs, → quality influences during extrusion, and → quality influences during injection molding

Court opinions


Cover glass

Fig. 103 (see also → cover glass thickness and → thin section)

Cover glass thickness

Cover glass and embedding material are part of the optical system. Therefore, the cover glass thickness is calculated to be 0.15 to 0.16 mm. The cover glass effect is negligible up to a numerical aperture NA of 0.40. The cover glass tolerance decreases from 0.40 up. Therefore usually cover glasses with a thickness of 0.15 to 0.16 mm are used, because the embedding material between the sample and cover glass is also included. A loading is also an advantage during the drying of the mounting medium. The permissible tolerance of cover glass thickness decreases with increasing NA. The cover glasses have a size of 18 mm × 18 mm (see also → aperture, numerical, → embedding media, and → glass slide).

Crack(s)

Cracks preferably develop at design errors (missing radii) in the area of stress peaks, in surface damages (notch, scratch), in inhomogeneities (pigment conglomerates and streaks, foreign material), at a media attack, warpage, and temperature change (see also → cause of cracking).

Craze(s)

A craze is a microfracture area with fine fibrils between the crack flanks. Crazes (microcracks with fibrils) occur only in ductile plastics through slow mono- or multiaxial tensile stress or volumetric shrinkage. Depending on the form design, particularly in a mass accumulation in the absence of holding pressure, partially different volume shrinkages and thus crazes are caused by molded part stress. In mono- or multiaxial tensile stresses, the fibrils are, depending on the crack flank angles, more or less inclined to the crack flanks. Multiaxial tensile stresses are produced at volume shrinkage. Such is the case in Fig. 376, which shows a microvacuole with fibrils that are perpendicular to the wall due to multiaxial volume shrinkage. Spontaneous fractures and brittle plastics usually do not develop crazes. However, rubber (impact resistant) plastics can form crazes due to faster tensile stress. Many crazes contain a white-colored bending zone, a so-called stress whitening (see also Fig. 376, → fracture center, and → stress whitening).

With a crockmeter, the resistance of a surface against abrasion or chemical attack is tested. For example, Crockmeter DIN EN ISO 105-X12 a car radio button is tested in accordance with DBL 7384, Section 4.9, with the following chemicals: synthetic hand sweat, plastic cleaner, tar remover, glass cleaner, detergent, lipstick, and cigarette ash. The chemicals are applied on a cloth. After the test with the crockmeter, the discolorations and residues that have arisen must be removable by wiping off using prescribed cleaning agents, and the surface of the radio button should then have no discoloration. The discoloration on the cloth and possibly changes in the surface are then documented in a table. Cross table

A cross table, a table that can be oriented in x-, y-, and z-directions, is used to position the sample. The sample that should be examined under a microscope is placed on the cross table (see also → microscopic examination).

Crosslinking


Cryogenic temperature fracture

→ Fracture at room and low temperature

Crystallite melting temperature range

The crystallite melting temperature range determines the temperature range in which the spherulites (“crystallites”) of a partially crystalline plastic melt.

85

Definitions

Technical Terms


Crystallites


Crystallites

Spherulites are developed during cooling of a molding compound of a semicrystalline plastic (“crystallites”) with semicrystalline and amorphous regions (see also → spherulites).

Curing

Thermosets have a crosslinked polymer matrix. During manufacture, for example during injection molding or extrusion, the thermoset molding compounds are still not crosslinked and can therefore be formed. If they crosslink at processing temperatures, they cannot be melted anymore. This process is referred to as curing. Using DSC analysis the curing and crosslinking of thermosets is investigated (see also → thermosets, → DSC analysis, → extrusion, → plastics, crosslinked, and → injection molding).

Customer contact


Customer inquiry

→ Questions for the customer, → report preparation, fast and competent

Cutting

The main cutting methods are those to make a thin section, block section, or scalpel cut, as well as cutting with scissors or a knife (see also → thin section, → block section, → sample preparation, and → scalpel cut).

Cycle time

The injection molding cycle time is the amount of time between the shot sequences of the molded parts. The shorter the cycle time, the more mold parts can be produced in a given time. Extrusion is a continuous process. Therefore, there is no cycle time. Molded part and machine size as well as the temperature of molding compound and mold have the greatest impact on the cycle time and thus the production costs.

Definitions

Technical Terms

Magnitudes of influence and contexts can be seen under → injection pressure, → injection rate, → following shot, → molding compound, → molding compound, cold, → molding compound, reinforced, → molding compound, reduced, → molding compound temperature, → molding compound temperature, too cold, → friction, → glass fiber content, → fiber breakage, → homogenization, → surface quality, → turbulence, → processing parameters, → reinforcing materials, → warpage, → viscosity, and mold temperature (see also → quality influences during injection molding). Damage reenactment

A damage reenactment is used to prove damages. Therefore, good parts, such as retained samples of the damaged series or of a new batch, are exposed to the same or suspected damage effects (see also → retained samples).

Damages, mechanical

Mechanical damages include a dent, a scratch, or a groove. A dent is caused by pressure or impact damage. Scratches and grooves are line-like damages in the molded part surface due to a contaminant or another outside influence (see also → dent, → groove, → scratches, and Figs. 92 and 562).

Dark and bright field slider

→ Microscope parts

Dark field contrast, incident light

Fine structures in the sample diffract the oblique light that is coming from the condenser into the objective; finer structures diffract more light. These shine brightly in front of a dark background image (see also → contrast processes in microscopy).

Dark field contrast, transmitted light

The dark field contrast AL-DF suppresses the gloss effect and shows the color more clearly than the other contrast processes. In normal incident light, a black surface is hardly distinguishable from a white one because both often have a silvery shine. An examination in the dark field contrast AL-DF is only possible with a small working distance and large aperture. A coaxial sample illumination through the objective is also particularly suitable for glossy surfaces (see also → contrast processes in microscopy).

Dead corners in the mold

“Dead corners” are areas in the injection molding unit or in the mold in which the molding material lingers for a long time and can therefore be thermally damaged (see also → overheating, thermal).

Deburring

Deburring is the removal of a → burr formation.

Declination angle s

→ Knife angle for thin sections

Decomposition, thermal

Over time, thermal overheating leads to thermal decomposition. The cause may be excessive (high) temperatures or lower, long-lasting temperatures. Thereby a destruction of the plastic matrix occurs by degradation of macromolecular chains, causing outgassing and black coloration (see also → degradation, → diesel effect, → macromolecules, and → overheating, thermal).

Defective vision

Defective vision of the eye complicates microscopy. Spherical eyeglass lenses do not create problems, but toric lenses will. Examination with toric lenses (eye cylinder) is not recommended. The lenses should be AR coated. Breaks should always be taken when there is eye fatigue because one’s concentration decreases and microscopic abnormalities may be overlooked (see also → microscopic examination and → microscope optimization).

86

Dent


Technical Terms


Deformation

Molded part deformation can arise from a too-early demolding of molded parts that are still soft, a high ejection speed, poor demoldability from the mold with missing draft angles, mold overfilling through high injection and holding pressure, a strong undercut, high mold roughness, or due to a negative pressure between the molded part and mold during ejection due to poor ventilation (see also → deformation layer, ventilation and → plastic deformation).

Deformation layer

→ Deformation, → grinding, → polishing, → plastic deformation

Deformation, plastic → Plastic deformation A chemical or mechanical degradation of the molded part surface is caused by a media attack or wear, and a chemical or thermal degradation of the matrix (the structure) is caused by a media attack or by increased temperature exposure (see also → aging, → hydrolysis, → solvent, → matrix, → media attack, → stresses, → stress corrosion, → overheating, thermal, → wear, → changing temperatures, and → decomposition, thermal).

Degree of dryness

→ Residual moisture

Delamination

Delamination is a layer separation (chipping). It can happen when the same or opposite directions of the molding compound flow (reversal of the flow front) into pigment separation layers (pigment streaks through poor homogenization), especially at long filling times and under the influence of internal and external forces (shrinkage, bending, compressive, and tensile stresses). The molding compound that is close to the sprue and first freezes on the cold mold wall becomes increasingly thicker and colder with increasing filling time. Molding compound flows still further under this cold layer until the mold is completely filled. It is however only insufficiently “bonded” with the already frozen molding compound and can therefore easily delaminate. During delamination, film-like layers, mostly in the vicinity of the sprue, dissolve from the molded part surface. Other causes include cold edge zones, mold oils or greases, foreign material after a molding compound change, shear flows (high injection rate), and flaking at a high holding pressure in a cold mold, as well as media attacks (cleaning agent) at stress-bearing shear zones. Some plastics such as PFA (perfluoroalkoxyalkane) are particularly prone to delamination (see also → injection rate, → foreign material, → reversal of the flow front, → hot-cold streaks, → cold flow, → flaking, → marginal zone in amorphous plastics, → marginal zone in semicrystalline plastics, → marginal zone, poor in spherulites, → shearing, → streaks, → surface refining, → coating, → electroplating error, → adhesive tape method, and → preparation techniques).

Demolding

For demolding, mold halves (or parts) are sometimes heated up higher to ensure that the molded part shrinks, for example onto a mold core, which will make demolding easier (see also → ejection and → demolding errors).

Demolding agents

Demolding agents (release agents) are sprayed into the mold so that the molded parts can be removed from the mold faster and more easily. It is important to have a uniform distribution, spray duration, and sequence. Demolding agents that are diffused into the molded part can diffuse out again after some time, causing color changes on the surface. Demolding agents based on polytetrafluoroethylene PTFE (Teflon) or silicone SI are very common in carrier liquids. Some demolding agents supposedly do not need to be washed off. This requires, however, a thorough examination to avoid future complaints (see also → efflorescence and → residue).

Demolding errors

Demolding errors occur, for example, in the absence of draft angles in the mold, in the case of holding pressure errors, or when the mold temperature is higher in the area of the shrinkage side. The molded part adheres better to the mold by shrinkage (see also → ejection, → demolding, → holding pressure error, → post-crystallization, → quality influences during injection molding, → shrinkage, and → mold temperature).

Demolding onto conveyor belt

Demolding onto a conveyor belt is preferred over a → free-fall demolding.

Demolding problems → Demolding errors, → injection molding Density determination

Density determination of plastics is achieved by an MFR analysis or with the buoyancy method according to DIN 53479 and DIN EN ISO 1183-1 (see also → analysis of plastic materials and → MFR analysis).

Dent

A dent is an unwanted, rounded concave depression (dent, hollow) in the molded part or mold surface. It is caused by pressure or impact injury (see also → notch, → scratches, → surface defects, → polishing, → groove, → packaging and transport, and → damages, mechanical).

87

Definitions

Degradation

Definitions


Deposition

Technical Terms


Deposition

A deposition is a physical or chemical → residue on the molded part surface.

Depth of field

A sample under the microscope has a varying height (depth). If an objective has a good depth of field (or depth of focus), the sample is in focus over the entire depth (over all height differences). The depth of field increases with the size of the numerical aperture (see also → aperture, → image resolution, → multifocus, → field diaphragm, objective, and → topography).

Design error

Design errors include the following: the sprue is too small (high shearing of the molding compound), the sprue or the weld lines are in the area of the main stress (risk of fracture), large wall thickness differences, flow paths are too long (molding compound flow, reduced), inserts in undersized wall thicknesses, missing draft angles, inappropriate type of plastic, nonrounded molded part transitions (notching), and too many cavities. A glass fiber amount above about 40% creates high abrasion, often with glass fiber accumulations in the flow shadow of webs and surface roughness, but also causes a loss of strength through microvacuoles and parallel layers of the glass fibers in weld lines. With high abrasion, glass pellets or ceramic powder, instead of glass fibers, are more suitable (see also → abrasion, → sprue, → weld line, → molded part flow, reduced, → insert, and → notch effect).

Destruction of the surface

→ Causes of aging and → hydrolysis

Determine crystallinity

→ DSC analysis

Determine filler and reinforcing materials

→ Filler and reinforcing materials testing

Determine foreign material

→ IR analysis

Determine melting point

→ DSC analysis

Determine molecular weight

The determination of a molecular weight distribution is carried out by gel permeation chromatography GPC or viscosity number VN. Identical sample areas from good and bad parts are often compared (see also → GPC analysis, → analysis of plastic materials, and → viscosity number (K-value)).

Determine monomers

→ GC analysis and → analysis of plastic materials

Determine plasticizers

→ HPLC analysis (see also → migration and → analysis of plastic materials)

Determine polymer blends

→ TG analysis and → analysis of plastic materials

Determine thermal stability

→ Vicat temperature and → analysis of plastic materials

DIC prism

The DIC prism (Wollaston prism) divides the linearly polarized light that is coming from the polarizer into two parallel, sinusoidal, orthogonal oscillating light bands of equal intensity and phase, with a distance of Dx. Only upon passage through the sample do the two light bands experience a path difference (phase shift) through different refractive indices n in the sample. Then the two light bands pass the second DIC prism (a DIC slider) and are reunited. They oscillate perpendicular to each other but with a phase difference. In the analyzer, the light bands are “drawn” near the oscillation plane of the analyzer and are brought into the same level or they increase or reinforce themselves in the intermediate image by interference. They then will shine brightly in the visual field against a black background image (see also → analyzer, → contrast processes in microscopy, → lambda plate (-plate), and → polarizer).

DIC slider

→ DIC prism

Diesel effect

A “diesel effect” is caused by compression of the trapped air in the mold at temperatures up to 1500 °C. The cause is a rapid injection with a high friction of the molding material in narrow flow channels (shearing) and bad mold venting. The “diesel effect” then produces a brown to black surface area of burnt molding compound. A similar error is also created by a long dwell time of the molding compound in the injection unit or in the mold in so-called “dead corners.” The thermally damaged molding compound also discolors brown to black, and brown streaks (brown streaks) occur in the molded part during injection (see also → injection, → venting, → friction, → shearing, → streaks, → dead corners, and → dwell time).

88

Drying time



Differential interference contrast method AL-DIC and DL-DIC

Using differential interference contrast methods AL-DIC and DL-DIC, elastomeric rubbers as well as filling and reinforcement materials are investigated: asbestos fibers, glass fibers, mica, kaolin, chalk, synthetic fibers, carbon black and talc. Using a lambda plate (-plate), the differential interference contrast methods AL-DIC and DL-DIC become color methods. The differential interference contrast method AL-DIC is suitable for studying the topography and is particularly appropriate for metallic surfaces (see also → DIC prism, → contrast processes of microscopy, → lambda plate, → polarizer, and → topography).

Diffraction angle a

The diffraction angle increases with decreasing particle size. It could go past the light rays on the objective. To prevent this from happening, a condenser is used, which bundles the light in the objective and has the same aperture as the objective (see also → aperture).

Diffusion adhesives

The diffusion adhesive that is used for thin ground samples is an acrylic adhesive. Finished thin ground samples that are glued with a diffusion adhesive can be dissolved from the glass substrate using alcohol and then transferred to a normal glass slide for microscopy (see also → adhesive and → thin grinding device).

Diffusion barrier

A diffusion barrier prevents the activation or migration of gases, such as a permeation layer for heating oil and gasoline tanks that prevent the escape of odorous substances (see also → oxygen diffusion barrier).

Dimensional error

Dimensional errors are mainly caused by a too-high or too-low mold temperature, a low or too-high injection and/or holding pressure, hard ejection, or improper exposure after demolding. Causes and influences of dimensional errors can be seen under → deformation, → injection rate, → molded part stresses, → free-fall demolding, → design error, → material residue transfer, → holding pressure, → post-crystallization, → plastic deformation, → shrinkage, → tempering, → over-injection, → warpage, → mold filling, poor, and → mold temperature).

Dioptric compensation

→ Microscope optimization, → ocular

Discoloration

Discoloration is a color change on the surface or in the interior of a molded part (sees also → color change, → surface discoloration, and → packaging and transport).

Discoloration, brown/red, with PVC

Brown/red discoloration with brownish-red spots is formed during the extrusion of PVC window profiles, if the added cadmium-tin stabilizer (Cd-Sn) contains inappropriate chemical compounds (see also → surface discoloration).

Dispersion

If there are pigment conglomerates that are more than 80 microns in size due to a subsequent coloring of the molding compound with a masterbatch, despite all good intent and homogenization, an unsuitable masterbatch carrier, a false masterbatch, or an unsuitable pigment has been used. In some known cases, for example, an unsuitable, cheaper carbon black pigment from the raw material supplier was used that did not disperse, or there was an undesired confusion in the injection molding process. The molded part resistance can also decrease during such an error (see also → coloring, → molding compound, primary colored, → molded part strength, → homogenization, → masterbatch, → matrix, and → carbon black streaks).

Dissecting needle

Fig. 103 (see also → thin section)

Dissolve plastic materials

→ Dissolving of plastics

Dissolving (of plastics)

Plastics can be dissolved in solvents. This is important, for example, in the determination of the fiber content in a molded part (see also → solvent, → fiber length determination, → glass fiber breakage, and → plastic materials).

Distinctive features

Distinctive features are quality and damage features that are found in a sample upon visual or microscopic examination. Distinctive features should be photographed immediately (see also → report preparation, fast and competent, → microscopic examination).

DMA analysis

The glass transition of plastics is determined with the dynamic mechanical analysis DMA.

Double refraction

Double refraction samples (writing appears twice when viewed throught it) include spherulites, chalk, kaolin, talc, quartz, calcite, zircon, apatite, corundum, starch, and sugar. Double refraction is also created by material stresses, such as stresses in PMMA, PS, PC, PETP, and CA (see also → DIC prism, → lambda plate (-plate), → polarization contrast, → polarizer, and → polarized light).

Drawing blend

→ Extrusion

Drying time

→ Residual moisture

89

Definitions

Technical Terms


Technical Terms


DSC analysis

With DSC analysis (differential scanning calorimetry), polymers and additives are determined as well as their melting point, crystallinity, and oxidation. The glass transition temperature range is measured by DMA analysis or DSC analysis. The start of the glass transition temperature range (or softening temperature range) begins at the glass transition (softening point) with softening of amorphous and semicrystalline plastic materials (see also → ODSC analysis).

DIN 53765, ISO 11357-2

Definitions

DSC analysis

Dwell time

The dwell time is the passage of time between the granulate intake from the hopper, heating, plasticizing, and homogenizing until the start of injection into the mold (see also → injecting, → homogenization, → plasticizing, and → injection molding).

Edge effect in the SEM

The edge effect is a distinct brightening at sample edges and protrusions because more secondary electrons (Se) are emerging there.

Efflorescence

Efflorescence is a residue caused by a migration of ingredients from the molded part to the surface (see also → migration and → residue).

Ejection (demolding)

When ejecting, the finished part is ejected with ejectors (e.g., ejector pins and plates) from the mold (see also → ejector mark and → demolding error).

Ejector mark

After cooling of the injected molding compound in the mold, the molded part is usually removed from the mold by ejector pins (or ejector plates). Particularly in an early ejection, the ejector pins leave a mark on the molded part surface, as an ejector mark.

Elastomer(s)

An elastomer (PUR, SI, SBR, NBR) is a chemically (weakly) crosslinked, flexible, and extensible plastic material. The injection moldable and extrudable preproducts only crosslink at the processing temperature (see also → thermoset, → type of plastic).

Elastomer, thermoplastic, TPE

→ Thermoplastic elastomers (see also → type of plastic).

Electroplating

Plastic-molded parts are metallized to beautify or improve aging (vaporized or electroplated). Electroplating (metallization) protects against UV, media, and temperature influences (see also → electroplating error, → surface refining, and → surface errors).

Electroplating error

Electroplating errors (see also Figs. 265–277) are caused by suspension in the electroplating bath (too dense), gas emissions, bath makeup (wrong), baths (aged), bath impurities, weld lines with and without air induction, bubbles in the metal layers, delaminations, diesel effects, degreasing (poor), grease residue, fingerprints, stains (dried-on), molded part errors (surface defects), molded part stresses, electroplating shadow, mass inversion (Fig. 231), handling errors (when inserting, removing), cold flow regions (cold flow), cold flow lines, plastic particles (displaced), conductive layer (too thin or missing), marks (due to suspension), dull spots, metal layer (missing), oil residues, moisture residual in the molded part, salt deposits (Fig. 268), cleanliness (lack of), delamination, streaks, transport and packaging influences, over-injecting, injuries (mechanical), predrying (deficient), and mold deformations. For a microscopic examination, the electroplating layers are removed up to the damage area (for example, the chromium layer with HCl 25% for 3 min at 30 °C, or 40% HCl for 1 min at 65 °C) and existing bubbles are opened. Attention is paid to the quality and the number of electroplating layers, and the molding surface should then be examined for molded part errors and compared with a freshly molded part (or reference samples). Sometimes a molded part error correlates with a later electroplating error. Then the blame lies with the injection molder, if packaging and transportation influences can be eliminated. If not, the research must be continued. Bubbles develop due to media outgassing or inadequate predrying in surface areas with outstanding glass fibers and air induction (delaminations, weld lines, mass inversions, cold-flow areas). Demolding and cleaning agents from the injection and also chemicals from the electroplating baths penetrate into these bubbles. Moreover, the bath temperatures can temper the molded parts, molded part stresses and delamination can be activated, and outgassing media (vapor pressures) can change the surface and cause blisters. With high residual moisture, an outgassing occurs on the entire molded part surface and not only in a small area. If partial bubbles always occur in the same area, the cause is not a lack of predrying. In this regard, the protection assertion from the electroplater is often unsubstantiated. Bubbles with a sharp edge develop more rarely at the bottom area of vertically hanging molded parts. As usual, after cleaning, heating is performed with chromic acid, and a conductive layer (usually palladium) and several micrometers of nickel are then chemically applied and are then copper plated, matte nickel plated, or chrome plated. If the bubbles do not have any inclusions after opening and the freshly molded

90

Embossing offset


Technical Terms


Electroplating error

parts (often retained samples) have a comparably nonporous, glossy surface without moisture streaks or residues (mold release agents, oils and fats, dirt), the cause of damage may be a bath liquid or a dried pickling or cleaning agent, which diffuse again at the lowest point in the copper bath, following gravity. However, this must be done during the conductive layer or copper construction, because the electroplating layers are brittle and hard, and therefore sharp-edged bubbles cannot subsequently form. Domed bubbles with a sharp bubble edge therefore always develop with the start of the first metal layer. Bubble-like delaminations of the metal layers are possible with poor adhesion. The bubbles are then flat on a large area without a sharp edge.

(continued)

Electrostatic surface treatment

The purpose of an electrostatic surface treatment is to increase the wettability by the use of a corona treatment with a high DC voltage of, for example, 5000 V (see also → wettability and → corona treatment).

Element determination

→ ESCA analysis

Embedding

Embedding usually takes place at room temperature (cold mounting) for better handling, clamping ability, and larger adhesion surface and edge strength. Samples with clamping surfaces that are not parallel or sensitive are embedded in EP and UP resins (two-component resins) or acrylates (one- and two-component resins). The sample is placed on the bottom of a round polyethylene casting mold using double-sided tape, and the intermixed embedding media, which is thoroughly stirred with a spatula or stirring machine, is poured over the sample. For faster removal of the air bubbles, use a vacuum (vacuum embedding). Narrow cavities with long flow paths should be injected with the embedding media, which is filled into a syringe. EP and UP have low shrinkage and cure in about 8 h at room temperature. Heating accelerates the curing but can cause overheating and warping through an exothermic reaction. Heating reduces the viscosity of the embedding resin, which will enable a better filling of the pores. Especially for foams, the edge strength increases during cutting or grinding. A UV lamp can accelerate curing in two-component resins. Although heating accelerates the curing time, it also increases the reaction temperature, whereby the sample may overheat. Therefore, good heat dissipation should be ensured. The curing temperatures of 2C resins are at about 50 °C and for one-component resins mostly over 100 °C. But they have, however, short curing times of only about 20 minutes. Embedding at elevated temperature (→ hot mounting) takes place at about 50 °C and accelerates curing. Burns may be caused through mixture errors or aged components (see also → embedding in a vacuum, → embedding media, → grinding, → cutting, and → warpage).

Embedding in a vacuum

For better removal of air bubbles after embedding, hardening takes place at 50 °C in a vacuum bell or in a vacuum chamber with a vacuum of about 500 mbar. Thus it can be ensured that air bubbles are removed. At the same time, the heating causes a better capillary action through the viscosity decrease of the embedding resin, which is also penetrating into small cavities (see also → embedding).

Embedding media

Common embedding media are epoxy resins, unsaturated epoxy resins, and polymethyl methacrylates (PMMA). Epoxy resin has been working very well as an embedding medium for molded samples. Diffusion adhesives that are acrylic-based are used for adhesion. Water-soluble cyanoacrylate tissue adhesives are also used (see also → thin section, → thin grinding device, → embedding, and → Canada balsam).

Embossing offset

An embossing offset in injection molding through shifted mold halves, for example at a knocked-out guide (bolts, pins, etc.), produces changes in the molded part surface. But also the core offset, at a high injection speed and high injection pressure, causes an embossing offset. The same happens during extrusion, when the embossing of, for example, corrugated pipes is done too late (see also → injection pressure, → injection speed, → extrusion, → core offset, → surface errors, and → injection molding).

91

Definitions

If the examined molded part surface has no sharp-edged bubbles (even for a freshly molded comparison sample), it is very likely that a protracted contamination from a dirty cleaning bath evaporated, depending on how the molded part was suspended, for example in the lower area. If bubbles arise at the same place during electroplating, there is a “systematic error” (see also → aging, → bubble, → weld line (with and without air induction), → bubble, → delamination, → diesel effect, → error, rheological, → error, systematic, → moisture streaks, → stains, → molded part stresses, → mass inversion (with and without air induction), → glass fibers, → inversion layers, → cold flow, → surface error, → residue, → streaks, → tempering, → turbulence, → over-injection, → packaging and transport, → predrying, and → mold venting).

Definitions


Embrittlement

Technical Terms


Embrittlement

Embrittlement and fracture sensitivity are generally caused by a chemical, thermal, and mechanical degradation in overheating, shearing, and destruction of the macromolecules. A high MFR increase between the molding compound and the finished molded part indicates a high shearing or high molding compound temperature, or a long dwell time in the cylinder or the sprue system. Remedy: Increase the gate (e.g., use a fan gate), polish the runner, control the nozzle heater, use a vented screw (with PFA dissipate hydrogen sulfide), use a nonreturn valve to reduce flow resistance, reduce screw speed, control screw gap, adjust the injection molding machine to the shot weight, reduce stagnation pressure, optimize mold venting, increase mold temperature, and temper flow paths evenly. Especially with PFA (see Fig. 385, notch sensitivity) and PC-molded parts with inadequate predrying (see also → degradation, → additives, → aging, → enlarge the gate, → causes of fracture, → coloring, subsequent, → color streaks, → moisture in the molding compound, → molding compound temperature, → molded part stresses, → filler materials and reinforcing materials, → glass fiber breakage, → granulate, unmelted, → hot-cold mixture, → hydrolysis, → inhomogeneities, → cold flow, → notch effect, → conditioning in water, → plastic materials, → plastics, semicrystalline, → solvent, → matrix degradation, → media influence, → holding pressure error, → post-crystallization, → post-shrinkage, → surface errors, → oxidation, → marginal zone for amorphous plastics, → marginal zone for semicrystalline plastics, → marginal zone, poor in spherulites, → residual moisture, → crack causes, → redirecting the crack, → shearing, → stresses, → stress crack corrosion, → spherulite streaks, → tempering (stress reduction), → overheating, thermal, → ultraviolet radiation, → vacuoles and blowholes, → processing, cold, → crosslinking, → reinforcing materials, → dwell time, → predrying, → changing temperatures, → mold temperature, and → decomposition, thermal).

Embrittlement of PFA

→ Embrittlement (see also Fig. 385)

Embrittlement of PVC

→ Embrittlement, → level of gelling of PVC, and → ODSC analysis with DSC analysis (see also Fig. 23)

Error during painting

→ Painting error

Error influences, human

Causes of human error factors are fear of job loss and excessive demands, amount of work, attention (lacking), training (education), promotion (blocked), lack of experience (competence), recreation deficiency, fatigue, quality of leadership (poor), health loss (diet quality, luxuries, drugs, narcotics), lack of concentration, termination (internal), motivation (insufficient), negligence, anxiety, overwork, fatigue, low pay, education (lacking), and fear of the future (see also → influences on quality and costs).

Error, rheological

Rheological errors occur during melting, flowing, and processing of plastics, but are almost independent of the processing machine (injection molding machine, extruder, press, etc.). They are the same in all plastics and manufacturing processes and are only dependent on the processing parameters (temperature, time, pressure). Type of plastic, machine, or manufacturing processes only have a marginal impact on the appearance and are therefore negligible, as well as minor differences caused by different density, fillers, and reinforcing materials or media influences. Rheological errors look the same and have the same causes in all semicrystalline plastics—only the clarity can vary slightly. This correspondingly applies to amorphous resins. This knowledge is very valuable, especially if the dictionary is missing a wanted plastic. For example, a weld or cold-flow line for a PA6 molded part looks just like one for an ABS molded part. Rheological errors are → delamination (but only through hot-cold streaks), → mass inversion (with and without induction, see also → inversion layers), → large and small spherulites, → hot-cold mixture, → hot-cold streaks, → cold-flow errors, → spherulite deformation (Fig. 57), and spherulite cracks (Fig. 55). The plastic melt that results during melting is a plasticized (melted), honey-like flowing molding compound.

Error, systematic

92

A systematic error always appears at the same place, often at the same time in the same environment, or by the same person (e.g., always away from the sprue, 11:00 p.m. in the night shift by Mr. X). This realization leads very quickly to damage solution through skillful questions for the customer. Therefore it should already be determined in the preliminary examination whether a systematic error is present (see also → questions for the customer, → report preparation, fast and competent, → customer inquiry and customer contact, → painting error, → examinations, comparing, → packaging and transport).

Extrusion



ESCA analysis

Element determinations are performed on surfaces with ESCA analysis (electron spectroscopy for chemical analysis). This method is particularly suitable for studies of very small deposits on molded part surfaces (see also → type of plastic, → analysis of plastic materials, → MFR analysis, → MVR analysis, and → residue).

Etching

Easily soluble areas in the plastic are removed during etching by acids or acid mixtures, for example with chromic acid etching or xylene etching.

Evidence order

An evidence order is a description of the examination issued by the court and has to be mentioned in the beginning of the assessment. Answering the evidence order is done at the end of the assessment, clearly understandable and with full justification. An expert is not a clairvoyant and cannot always give an exact answer. But if he has an opinion (expert opinion from experience), the conclusions must be understandably accurate, especially for “laypeople,” as well as for a lawyer and judge (see also → report, → report preparation, fast and competent, and → microscopic examination).

Examination after order confirmation


Examination devices, microscopic

→ Macroscope, → microscope, → microscopic examination, → microscope parts, → polarization optics, → scanning electron microscope, → universal microscope, and → stereomicroscope (see Figs. 104–107)

Examination methods, microscopic

→ Main examination, → contrast processes of microscopy, → microscopic examination, → examination, comparing, → examination, visual, → examination devices, microscopic, and → preliminary examination

Examination, comparing

Rapid results and time savings result from comparing examinations in microscopic, chemical, mechanical, and thermal analysis (see Figs. 540–556). The following options are common: 1.

The good part is compared with the defective part. But beware; the alleged good part is sometimes an unexamined good part, which means an unrecognized defective part.

2.

The retained sample (often an alleged good part of previous production) is compared with the defective part from new production.

3.

If a good part is available, the defective part must be microscopically examined and the abnormalities are determined by thermal, mechanical, or chemical methods (e.g., DSC, IR, or MFR analysis).

See also → DSC analysis, → error, systematic, → questions to the customer, → report preparation, fast and competent, and → IR analysis, and → MFR analysis. Examination, microscopic


Examination, visual

→ Visual examination (see also → preliminary examination)

Examine the flow behavior

The flow behavior of plastics is examined by means of a filling study, MFR analysis, MVR analysis, and viscosity numbers (see also → molding compound, flow behavior, → filling study, → MFR analysis, → MVR analysis, and → viscosity number).

Examine welding seams

→ Hot air treatment

Example searches

→ Search examples

Expert opinion


Exposure test

→ Aging resistance, → resistance to chemicals, and → impact assessment.

Extrusion

During extrusion, granules or powder is fed, mixed, plasticized, and forced continuously through a perforated disc (usually with screen packs) by a rotating screw from the hopper into the cylinders, which is electrically heated with jacket heaters, and is formed and cooled in the subsequent mold. The perforated disc and screen packs increase the back pressure and improve the homogenization. In contrast to injection molding, there is no collection chamber and the screw is much longer. Extrusion is a continuous process in contrast to injection molding. The back pressure can also be increased by an axial screw displacement in the conveying direction or with a jam bushing in front of the screw tip or by increasing the mold resistance (see also → homogenization, → perforated disc, → perforated disc imprinting, → quality influences during extrusion, → strainer impression, → screen pack, → jacket heating, and → screw).

93

Definitions

Technical Terms


Extrusion

Technical Terms


Extrusion

In the production of pipes (pipe extrusion), the pipe, which is still plastically exiting the extruder head, is calibrated by drawing apertures, cooled in the subsequent water bath, stripped with a chain pull, and then the continuously formed pipe is shortened with a saw.

(continued)

Definitions

In film and board production with a slit die, the resulting film is calibrated and cooled through subsequent rollers. In extrusion blow molding (film blowing), a plastic, thin pipe, which is exiting from an angle head, is blown up, cooled, and flat wound using a cross-flow fan (see also → slit die extrusion, → film blowing, → film production, → blow molding of hollow objects, → link chain, → jacket heating, → pipe extrusion, → screw, → injection blow molding, → water bath, and → drawing blend). Extrusion blow molding

→ Extrusion, → extrusion blow molding, → blow molding of hollow objects (see also → rotational molding and → injection blow molding)

Eye

The eye, which is directly connected to the brain via the optic nerve, has a higher power range than modern imaging devices in speed, resolution, light-dark adaptation, sharpness, and depth of field. The iris controls the brightness and the lens focuses the image on the retina from a 25 cm visual distance to infinity. The retina contains light receptors, about 120 million rods for night vision (gray) and only about 6 million cones for color vision (day vision). The rods and cones convert the light into electrical signals. Then they travel from the optic nerve into the brain, where they are perceived as color and brightness. Three types of cones, sensitive to short-, medium-, and long-wavelength light, detect blue, green, and red light, respectively. On the opposite side of the pupil is the center of the retina that is most sensitive to color vision, the fovea, and, just below, the blind spot (papilla). At the blind spot, the retina connects via the optic nerve to the brain, and the blood vessels connect with the choroid; no rods or cones are found there (see also → fovea).

Eyeglass wearers

→ Defective vision

Fading

Plastics fade by the UV light of the sun (especially red pigments), white fluorescent light tubes (which is usually underestimated), and chemical attack during service life (e.g., photosensitizing of cleaning and maintenance products). The application frequency of the cleaning agents is as important as the concentration. High temperature, humidity, and chemo-atmosphere also increase the fading rate.

Fibrils

Fibrils are ductile stretched tips in a fracture surface or between crack faces (see also → fracture center).

Field glass principle for the stereomicroscope

A stereomicroscope with a field glass principle has parallel visual axes. This is a condition for multifocus recordings (see also → Greenough principle stereomicroscope, → microscope parts, and → multifocus).

Field lens

The field lens or front lens is located in the microscope above the condenser, and can be swiveled in and out. It is swiveled in at objective apertures NA = 0.25, equivalent to about a magnification of M = 100, which increases the illumination (see also → universal microscope).

Field of vision, black

→ Polarizer

Filler materials and reinforcing materials

Filler materials are, for example, wood fibers, nanofillers, chalk, kaolin, magnesia, and sand. These materials increase the stiffness, often produce a matte surface, prevent sink marks, even with large wall thickness, but can reduce the tensile strength. Nanofillers, in contrast, mostly improve the optical and mechanical properties. For example, a calcium additive Ca should increase the stiffness, strength, and sliding properties in the extrusion of PVC-U pipes. This is also achieved up to an optimum by a good adhesion promoter (finish)—with increasing fineness of the Ca particle and dispersibility (homogenization) in the molding composition. In addition, however, an increased Ca content has a harmful effect (like foreign material) on the strength (see also → additives, → aperture, → adhesion, → fracture at room and low temperature, → sink marks, → filler materials and reinforcing materials testing → lubricant, → nanofillers, → nucleating agents, → orientation, → phase contrast PH, → polished sample, and → WPC plastics).

Filler materials and reinforcing materials testing

For the investigation of fillers and reinforcing materials, fracture surfaces are studied using light and scanning electron microscopy (through dissolution in appropriate solvents) with thermal analysis, by incineration of the plastic matrix at 650 °C or by means of thermogravimetry. In order to determine the content of chalk, a filling and processing agent in plastics, for example in PVC-U water pipes, a sample is taken, placed in sulfuric acid H2SO4, and this is evaporated with a Bunsen burner; then the residual sample is heated at 950 °C in a furnace (muffle furnace). In this way, the calcium Ca content in the PVC is converted into calcium sulfate and thus not dissolved by the released hydrochloric acid HCl from the PVC (see DIN EN ISO 3451-5). The chalk content of the PVC-U sample is then calculated stoichiometrically from the remaining sulfate ash content with approximately 1.36 × chalk content% (SKZ formula).

94

Fluorescence contrast AL-FL and DL-FL


Technical Terms


Filler materials and reinforcing materials testing

In elastomers and rubbers, the fillers are determined by, for example, differential interference contrast, whereas polarization contrast is used for thermoplastics (see also → differential interference contrast, → filler materials and reinforcing materials, and → plastic materials).

(continued) Filler materials in elastomers and rubbers are, for example, examined with the differential interference contrast (see also → differential interference contrast, → filler materials and reinforcing materials, → filler materials and reinforcing materials testing, and → plastic materials).

Filling study(ies)

If the mold quality does not meet the requirements, a filling study with various successive mold temperatures, then molding compound temperatures, then injection speeds and pressures, and finally with various holding pressures, is recommended. It is recommended to only change one value and first start with the mold temperature. If the filling study is no improvement, a mold adjustment (e.g., polish or repolish the sprue/gate) will be necessary. For example, an adjustment of the sections in a runner improves the form quality in all cavities. This requires that the sections are partially polished, because the lengths of flow paths between the sprue and the mold cavities are usually different. The goal is a possibly equal filling of the mold cavities (see also → sprue, → examine molding compound flow behavior, → holding pressure, → cavities, and → polishing).

Film blowing

In film blowing (extrusion blow molding), similar to blow molding of hollow objects, first a thin-walled pipe with a large diameter is extruded, then guided over an angular head into a crossflow fan, blown with compressed air, and cooled, and the resulting film tube is laid out flat and wound onto a roll (see also → extrusion and → film manufacture).

Film manufacture

Conventional manufacturing processes for films are slit die extrusion, film blowing, or calendering. The film, which is created in the film manufacture through a slit die, is calibrated over subsequent rolls, cooled, and wound up. In calendering, films of the highest accuracy are created with a smooth or textured surface (see also → slit die extrusion, → extrusion, → film blowing, or → calendering).

Filter

→ Illumination, → color filter

Fire prevention equipment

Fire prevention equipment usually consists of oxygen-binding additives such as chlorine, fluorine, and bromine compounds (see also → additives).

Fire prevention treatments

Tetrabromoxid, antimony trioxide, lead in overdose or high processing temperatures to separation and formation of craters in the coating of plastic surfaces, especially when exposed to moisture.

Fisheye

A fisheye is a stretched or torn film area (short crack) and looks like a fish eye with sharp corners. A fisheye is caused by the film stretching during blow molding in an inhomogeneous film area.

Fishtail nozzle

→ Slit die extrusion, → extrusion

Flaking

→ Cold plug, → particle

Flame treatment

The flame treatment of a plastic surface causes a better wettability and adhesion through the associated surface oxidation. Thus the paint adhesion and bonding strength increases and is even made possible for some nonpolar plastics (e.g., PE, PP, PB, PIB). Other methods are electrostatic and chemical surface treatments (see also → wettability and → priming).

Flocking

When flocking, PVC flakes, after an electrostatic charge of the plastic surface, are vertically drawn to the surface and are embedded there (see also → surface refining).

Flow lines

A flow line is formed in an unexpected area at an unexpected confluence of mass flows, for example, a core offset. A weld line, however, is created in an expected area, for example after a core flowing or at the confluence of two or more mass flows. Flow lines (cold flow lines) in a molded part surface are a rheological error. They are created by molding compound flows, which are flowing at different rates due to differences in temperature and/or flow resistances in the mold (see also → core offset, → error, rheological, → mass flows, leading, → reversal of the flow front, → weld line, and → weld line number).

Flow resistance

→ Molding compound, flow behavior, → reinforcing materials, → cycle time.

Flow streaks

→ Paint streaks (see also → streaks)

Flowability

→ Molding compound, flow behavior

Fluorescence contrast AL-FL and DL-FL

Fillers and reinforcing materials, such as silica (SiO2) and magnesium oxide (MgO, ZnO), of elastomers and rubbers are examined with the fluorescence contrast AL-FL and FL-DL (see also → contrast processes in microscopy).

95

Definitions

Filler materials, testing

Definitions


Fluorination

Technical Terms


Fluorination

Fluorination of the surface makes molded parts chemically resistant to chemical influences, such as gasoline and diesel oil. In the automotive industry, the moldings made of polyamide PA are chemically resistant.

Foaming

During foaming, the plastic matrix is inflated by gases (such as CO2). Many small gas bubbles (cells) develop in the plastic, and its density and thermal conductivity decrease. There are open-celled and closed-celled foams. Sample preparation for structural studies is usually done with a thin section, cold fracture in nitrogen, or razor blade cut.

Following shot

The injection process in injection molding is also called “shot,” and the subsequent one is called “following shot.” A material residue transfer occurs when molding compound particles get caught in the mold after demolding and are over-injected with molding compound during the following shot, and for example are incorporated flat into the surface. If the displaced mass particle protrudes through the mold surface, an over-injection occurs (see also → material residue transfer and → over-injection).

Foreign granulate

Foreign granulate is an undesirable foreign particle (or granulate) of foreign material in a molded part or granulate. It is often harder to melt than the matrix and is then present in an unmelted material (see also → foreign particles).

Foreign material

Foreign material is a → foreign particle and → foreign granulate.

Foreign particle

Foreign particles are undesirable in plastics because they deteriorate the quality (e.g., appearance, strength, chemical resistance). A foreign particle consists of a different plastic than the molding compound or material (impurities, sand, metal, etc.), and it is often difficult to melt or cannot be melted at all (see also → foreign granulate and → particle).

Forming

→ Primary forming

Fovea

The entire field of vision is not consciously detected in microscopy. Only the well-defined, direct view (as in the 2° fovea area) is conscious and brings knowledge. Therefore, the sample should be “scanned point by point” with the eyes and any striking feature (even the slightest) should be noted. A reflection on the possible cause and prevention facilitates finding the technical term and the comparison with the figures in the encyclopedia (see also → eye, → visual awareness region, microscopic, and → report preparation, fast and competent).

Fracture

A fracture is a complete break. A distinction of the type of fracture is particularly difficult when the crack is chemical and the tear mechanical (by an external force) until the fracture occurs. Under the influence of time and temperature, media fractures and media cracks develop in a molded part by fats, oils, wetting agents, solvents, and ionizing radiation in the range of stress peaks. They usually appear as brittle cracks in atypical areas (for example, near the weld line) with a netlike surface profile, and the crack edges and the crack environment can show plastic deformations and spots. The crack surfaces are often glassy smooth and rarely have fracture edge cracks. The fracture surfaces have, depending on the plastic, following the fracture area, small or large fracture steps (fracture edge cracks), often with a fracture area of 45° or more (the harder the plastic, the steeper) as well as parallel cracks. The velocity of the crack initiation also has a major influence. Mechanical fractures and cracks are caused by external influences, such as impact, shock, and tension or internal forces in the area of molded part stresses, by post-crystallization or shrinkage during cooling (see also → weld line, → fracture types, → causes of fracture, → craze, → stains, → stresses in the molded part, → solvent, → media attack, → media fractures, → media cracks, → post-crystallization, → wetting agents, → cracks, → shrinkage, → stresses, → temperature influence, and → plastic deformation).

Fracture center

Upon loading a cross-section, inhomogeneous, circular areas (normal stress centers) with perpendicular fibrils fail first. At a tear (Fig. 322), the fibrils and the mostly parabolic stages of cracking (fracture parabolas) are pointed in the direction of the crack propagation. The “tip” of a fracture parabola points to the fracture area (the beginning of the crack in the fracture center or normal stress center) and the ends are pointing to the crack. A crack that is leading to a fracture always starts with a center break or fracture center. It initially spreads circularly, and then opens up, following inhomogeneities, to a fracture parabola (or several). A fracture center results from stresses in a thermal stress area (through heat), in a mechanical damage areas (weld line, notch), or in an inhomogeneous defect by a foreign particle (see also → weld line, → fibrils, and → foreign particles).

Fracture stages

→ Fracture

96

Fracturing at room and low temperature


Technical Terms


Fracture test

Room-temperature fracture is only possible during the sample preparation of hard and brittle samples. The sample, which is clamped into a bench vice at room temperature, is broken at a previously inserted saw notch (fracture at a defined point) using pliers, a hammer, or between two flat tongs. The low-temperature fracture is used in tough, soft, and elastic samples. They become brittle after immersion in liquid nitrogen, which now allows the same fracture method as with the room-temperature fracture (see also → fracture at room and low temperature and → cryogenic temperature fracture).

Fracture types (author definitions)

A break is a finished crack. In the microscopic damage analysis of plastics, five main fracture types are used. These are short-term, long-term, media, temperature, and stress whitening. These are further subdivided into: Development

Adhesion fracture

Joining fracture is an adhesion at the adherend border (EN ISO 10365, ISO 472)

Bending fracture

Bending fracture with fracture flank, which is stretched on one side and compressed in fracture area

Brittle fracture

Through aging or fast crack initiation, also in tough plastics

Calotte fracture (dome fracture)

Annular compressive stress with dome-shaped fracture surface. Example: sheared plastic rivet in a bore hole with diameter shrinkage.

Cohesion fracture

Cohesion fracture with visible separation in the adhesive or adherend (EN ISO 10365, ISO 472)

Delamination fracture

With layered fracture areas

Fatigue due to vibration failure

Tear with fine fracture stages with varying load

Flow front fracture

Slow force induction and constant load with usually differently long fine fraction steps during discontinuous tearing

Definitions

Type of fracture

Long-term fracture With discontinuous tear and fine, even fracture steps at constant load Media fracture

Chemical attack usually in stress areas, with or without temperature influence

Melt fracture

Doughy heated fracture edges through rapidly alternating bending loads

Splinter fracture

Brittle fracture with outbreaks and splinters

Stress whitening

This term has existed for many years. Stress whitening is not a fracture yet but has a white coloring (crazes) in a bending zone or beginning fracture zone.

Torsion fracture

In hard plastics with wave-like fracture and increasing fracture area up to 45° and more in soft plastics for fast force induction

See also → causes of fracture, → craze, → crack, and → cracks. Fracture, edge cracks

→ Fracture

Fracture, nick (surface)

→ Artifact

Fracturing at room and low temperature

Fracture at room and low temperature is a quick sampling as well as a fast sample preparation at the same time. The resulting fracture surfaces show used fillers and reinforcing materials, their type, size, orientation, and distribution of matrix adhesion, directly in the incident or scanning electron microscope. Furthermore, the fracture behavior shares some information about the brittleness or embrittlement due to aging. Rigid polyurethane foams slightly notched with a scalpel cut can break easily and can be quickly examined. A room-temperature fracture is only possible for hard, brittle samples. The sample, which is clamped into a bench vice at room temperature, is broken at a previously inserted saw notch (fracture at a defined point) using pliers, a hammer, or between two flat tongs. The low-temperature fracture is used in tough, soft, and elastic samples. They become brittle after immersion in liquid nitrogen and are then broken as with the room temperature fracture (see also → aging, fracture test, → filler materials and reinforcing materials, → LM microscope, → scanning electron microscope, → scalpel cut, and → cryogenic temperature fracture).

97

Definitions


Free-fall demolding

Technical Terms


Free-fall demolding

In free-fall demolding, after opening the mold, the molded parts fall from a great height into a catcher, which is located below, and hit each other. This can lead to warpage and damage. Demolding onto a conveyor belt at the mold height is therefore much gentler (see also → demolding onto conveyor belt and → warpage).

Free-jet formation

→ Mass stream

Freezing in liquid nitrogen

After freezing in liquid nitrogen, elastic plastics can be fractured, and the striking features (additives, foreign material) in the fracture faces are examined microscopically. A scalpel or saw cut is made into the plastic surface before freezing so that the subsequent fracture occurs at a defined point (see also → preparation techniques).

Friction and local overheating

Friction is a shearing friction with heating of the molding compound through the screw, and friction in the cylinder, for example in injection molding and extrusion. Together with the dynamic pressure and the jacket heating, it causes homogenization and melting. Unwanted friction in narrow flow channels and in the sprue can lead to brown and burn streaks and glass fiber friction by local overheating (see also → sprue, → brown streaks, → glass fiber breakage, and → burn streaks).

Front lens

→ Field lens

FTIR analysis

→ MFR analysis

Fuchsine (coloring agent)

→ Coloring

Gate

The gate is the transition from the sprue to the molded part. A constructively misplaced gate causes a disturbed molding compound flow and, subsequently, molding defects. Usual types of gates are film gate, pinpoint gate, fan gate, sword gate, and direct gate. The gate, runner and, sprue comprise the filling channel to be removed on the molded part after demolding. A pinpoint gate requires no rework. A gate thread often develops after a premature ejection. (see also → sprue, → injection molding error, → mass stream).

GC analysis

The quantitative determination of monomers and additives is achieved by gas chromatography GC (see also → analysis of plastic materials).

Gelling, level of

→ Level of gelling

General causes of aging

→ Causes of aging

Glass fiber breakage

High friction and rapid injection through a narrow pinpoint gate shortens the fiber lengths and reduces the mold strength. The glass fiber length distribution of a molded part is determined with solvents according to the resolution of the matrix (resin) or by incineration in an oven at 650 °C. The exposed glass fibers are bloated in acetone, and their length is measured under the microscope, and the size fractions (distribution) are specified (see also → friction, → glass fiber fracture, → solvent, → media that can cause stress cracking, and → media cracks).

Glass fiber length distribution

→ Glass fiber breakage

Glass fibers

Glass fibers increase with homogenous distribution of the molded part strength, but also the weight and the warpage in the machine and in the mold. Glass fibers particularly tend to form parallel layers in the weld line, causing a reduction in strength. In flow shadows, glass fiber segregation occurs, which will lead to fiber enhancement in other areas (Fig. 116). High glass fiber content of over 40% significantly reduced the molding compound flow. Then microvacuoles and vacuoles can often form. In cold processing, glass fibers can protrude through the molded part surface (see also → weld line, → molding compound, flow behavior, → weight change, → fiber breakage, → microvacuoles, → vacuoles, → warpage, → reinforcing materials, and → viscosity).

Glass slide

A glass slide is a thin glass plate with the dimensions 26 × 76 × 0.9 up to 1.0 mm (see also → cover glass thickness).

Glass temperature

→ Glass transition temperature range

Glass transition

→ Glass transition temperature range

Glass transition temperature range

The glass transition temperature range is measured by DMA analysis or ODSC analysis. The start of the glass transition temperature range (or softening temperature range) begins at the glass transition (softening point) with softening of amorphous and semicrystalline plastic materials.

98

Grinding


Technical Terms


Glass transition temperature range

Semicrystalline plastic materials have two different transition ranges before complete melting. With increasing temperature, the ultimate tensile strength B and stiffness (Young’s modulus) decrease slowly up to the glass transition (softening point) – the beginning of softening in the softening temperature range – and then more rapidly until the semicrystalline regions (spherulites) melt at the end of the crystallite melting temperature range.

(continued)

Amorphous plastics do not have a crystallite melting temperature range. With increasing temperature, the ultimate tensile strength B and Young’s modulus decrease up to the beginning of softening in the softening temperature range. Melting begins at the glass transition point (softening point) (see also → DMA analysis, → plastic materials, amorphous → plastic materials, semicrystalline, → ODSC analysis, → plasticizing, and → spherulite(s)) A globule is a spherical particle (see also → foreign material).

Gloss measurement

Gloss is measured with a reflectometer at an R′ value of 20° (with high gloss, or if 60° R′ value is greater than 70), 60° (medium gloss), or 85° (matte finish or if at 60° the R′ value is less than 30). Causes of measurement errors are gloss differences on the surface, curvature of the measuring surface, wrong measurement geometry, different measuring points, roughness and graining of the measuring surface, and temperature at the measurement surface.

Gold plating, sputtering

→ Sputtering

Goose bumps

→ Orange skin

GPC analysis

The molecular weights of polymers, blends, and copolymers are determined by GPC (gel permeation chromatography) analysis. It measures the macromolecule length distribution more accurately than MFR and VZ analyses and provides information on the degradation by thermal or mechanical damage, aging, and masterbatch changes.

Graining

The graining of sandpaper shows the number of screen meshes per inch through which the largest abrasive grains still fall through.

Granulate contamination

To test the granulate for the presence of foreign material or contaminants, about 100 g of a bright granulate batch is spread (single layer) on a dark plastic tray (for dark granulate, vice versa) and is visually inspected. Granulate with impurities is usually very easy to recognize. They are sorted out and are further examined under a microscope in a Petri dish (diameter 8 cm) at 6- to 10-fold magnification.

Granulate, unmelted

Unmelted granulate is an insufficiently melted residual granulate or hard or unmeltable foreign granulate. The cause is a lower molding compound temperature or poor homogenization. The examination is performed on a thin section in transmitted light, without polarizing filter, so that even dark granulate residue will be visible (polarization creates a dark background). A particle that appears to be bright in transmitted polarized light in a thin section may be an unmelted, partially crystalline granulate. This is why a hole would be black in polarization, as is the object glass slide itself, as well as a torn conglomerate or an amorphous plastic particle (see also → coloring, subsequent, → molding compound, cold, → molding compound, reinforced, → molding compound temperature, → foreign granulate, → homogenization, → conglomerate, → contrast types, → plastic materials, → plasticizing, and → injection molding).

Gravimetry (determination of weight)

Gravimetry is a weight determination of the plastic content in a plastic compound with a precision scale (see also → analysis of plastic materials).

Gray streaks

Cloudy gray streaks are caused by → metal abrasion (see also → streaks).

Greenough principle in the stereomicroscope

This type of stereomicroscope has visual axes that are inclined 7 degrees to each other. Therefore, multifocus shots are not possible because the images drift apart with increasing working distance (focus settings) (see also → field glass principle and → microscope parts and → multifocus).

Grinding

The aim of grinding is to remove material to plane and refine the sample surface or to penetrate to a certain depth. Grinding is, like polishing, a machining process. There are ground sample types: the block ground sample, thin ground sample, and split ground sample. For grinding of thermoplastics and thermosets, seven sanding levels of graining, 180, 220, 320, 500, 800, 1200, and 4000, are common. Most often, 220 grit will be used to start with and a 180 grit in “lubricating plastics” (PE, PP, PB, PIB) to save time. It is important that the following finer grit removes the roughness of the preceding. This is achieved with the above-mentioned grain gradation. A grinding quality from a graining of 1200 is already sufficient for detecting macroscopic events. To examine microscopic structure components, polishing

99

Definitions

Globule(s)


Technical Terms


Grinding

with a surface roughness < 1 micron is often necessary. The surface is removed through the cutting action of the abrasive (silicon carbide SiC on wet-strength paper), which leaves scratches and plastic deformation (deformation layer). Here, a structural change is made up to the depth of the sample surface (total depth). The total depth increases with the graining number. It is the sum of the deformation layer, surface roughness, and depth of deformation and is dependent on the binding of the grinding wheel, graining, cooling, type of plastic material (temperature, fillers, hardness), and the grinding pressure (see also → thin grinding device, → graining, → scratches → type of plastic material, → polishing, → surface roughness, → plastic deformation).

(continued)

Definitions

Grinding

Groove

A groove is line-like damage in the molded part surface with retracted or broached beaded edges due to mechanical damage. It is deeper and wider than a scratch (see also → dent, → notch, → scratches, → surface errors, → polishing, → packaging and transport, and → damages, mechanical).

Ground sample

→ Block ground sample.

Guide pins

Guide pins center the mold halves when opening and closing (see also → mold breathing, → mold filling, and → mold offset).

Halogen light source Incident and transmitted light illumination in microscopes is usually done using halogen lamps. For the external lighting, a two-armed halogen light source (gooseneck lighting) of 150 to 250 W is often used in a macroscope with ring light and sickle aperture. The advantage of the sickle aperture is a change in brightness at a constant light color (about 5000 lux). By controlling the halogen lamp, the brightness and color of the light changes (see also → microscope parts). Haptics

The word indicates how a surface feels. If a molded part surface has good haptics, it feels good and has a good grip.

Hatch optical path

The hatch optical path consists of the field diaphragm, the sample plane, the intermediate image, and the retina. The field diaphragm LB controls the field of view and illumination in the hatch optical path (see also → aperture diaphragm, → Köhler illumination, → field diaphragm, and → optical path of the pupil).

Heat exposure

Location and size of the molded part stresses are often clearly visible after heat exposure close to the glass transition temperature. Therefore, the molded part is placed in a convection oven and the warpage is measured every day. The frozen molded part stresses cause shrinkage, especially in the larger wall thicknesses (mass accumulations). The higher the molded part stresses, the greater the shrinkage, and usually also the warpage (see also → molded part stresses, → tempering, → convection oven, → warpage, and → predrying).

Heat stabilizers

A heat stabilizer protects the molding compound from thermal degradation during processing and in the use of high temperatures (see also → degradation and → additives).

Hold pressure

→ Holding pressure, → holding pressure error, → lack of holding pressure, → holding pressure time, → residual mass cushion

Holding pressure

For shrinkage compensation, the holding pressure pushes molding compound from the residual mass cushion of the injection unit into the closed mold. The holding pressure size, time, and progress affect the following variables: molding quality, weld line strength, sink marks, demolding behavior, weight, burrs, dimensional accuracy, shrinkage, and vacuoles. A holding pressure that is too high can produce demolding problems, burr formation, core displacement, stresses (high frozen), and overfilling (change in weight). In a poor molding impression, an initially high holding pressure (about 95% of the injection pressure) is very beneficial, but there is a significant drop just before the end of the holding pressure time. Reasoning: An initially high holding pressure pushes more molding compound from the residual mass cushion in the already shrinking but still plastic molding compound in the mold, than at the end of the holding pressure time. This creates a good impression of the mold surface. A relatively high and long-acting holding pressure mostly only increases the molded part stresses (see also → impression (molded part impression), → aging, → deformation, → burr formation, → microvacuoles, → hold pressure, → holding pressure error, → lack of holding pressure, → holding pressure time, → post-crystallization, → post-shrinkage, → roughness, → residual mass cushion, → stagnation pressure, → vacuoles, → processing parameters, → warpage, and → mold impression, poor).

Holding pressure error

Holding pressure errors are caused by a lack of holding pressure and cause weld lines and reduced strength, sink marks, weight fluctuations, blowholes, dimensional errors, shrinkage, vacuoles, and warpage. A holding pressure that is too high creates demolding problems (deformation), burr formation, core offset, stresses, overfilling and warpage (see also → impression (molded part impression), → weld line, → weld line strength, reduced, → deformation, → sink marks, → demolding errors, → weight change,

100

HPLC analysis



Holding pressure error (continued)

→ burr formation, → core offset, → dimensional errors, → holding pressure, → lack of holding pressure, → holding pressure time, → shrinkage, → stresses, → vacuoles and blowholes, → warpage, and → mold filling).

Holding pressure time

During the holding pressure time, the holding pressure affects the residual mass cushion (see also → holding pressure, → holding pressure error, → lack of holding pressure, and → injection molding).

Hollow body, closed

Closed hollow bodies (seamless) are produced through → blow molding of hollow objects, → rotational molding, and → blow molding.

Homogenization

Homogenization is the optimum heating (plasticization) of a molding compound, for example during injection molding or extrusion, by mixing all of the ingredients (additives, pigments, filler, and reinforcing materials). A molding compound is homogeneous when all of the chemical, electrical, optical, and physical properties are the same over the entire cross-section. Homogenization errors lead to thermal streaks and pigment streaks, as well as to reduced molded part strength. Molded part defects can be caused by homogenization times that are too short. For subsequent coloring and poor homogenization, the pigments are insufficiently dispersed into the molding compound, which will allow a formation of pigment streaks and weak or uncolored areas (bright streaks, lines) (see also → extrusion, → masterbatch change, → pigment streaks, → plasticizing, → plasticization unit, → residual mass cushion, → streaks, thermal, and → injection).

Homogenization error

→ Homogenization

Homogenization, poor

→ Homogenization

Hot air treatment

Molded part stresses are plastically visible with a hot air treatment. A reduction of the molded part stresses also occurs through simultaneous tempering. For example, to detect the width of a heating element weld line, a block ground sample with SiC wet sandpaper, 1200 grit, is manufactured through the weld line and is then gently fanned with a hot air fan at 320 °C. By the hot air treatment, frozen welding stresses are freed and weld flow lines (of the weld line) are thereby made visible. The weld line width should reach a wall thickness of about 10 to 20% for good weld line strength (see also → molded part stresses, → preparation techniques, and → tempering).

Hot-cold mixture

A hot-cold mixture results in the mixing of warm, internal with cool, external molding compound through an insufficient homogenization or oscillating mold filling at too-rapid injection or extrusion. Large spherulite streaks are generated in the semicrystalline plastics in the fine-spherulitic matrix (large and small spherulites) due to the mixture in the molding compound area of different temperature ranges. Cracks in the streaks are then often generated by mechanical stresses through a notch effect between the large and small spherulites. The cause of a hot-cold mix is usually a mass inversion (see also → delamination, → error, rheological, → mass inversion, → hot-cold streaks, → homogenization, poor, and → spherulite streaks).

Hot-cold streaks

The orientation of the macromolecules in hot-cold streaks is made visible through isochromatics in polarized transmitted light, in amorphous plastics. They are generated through flow processes in shaping. Hot-cold streaks in semicrystalline plastics include large and small spherulites, which are recognizable by their structural differences, also only in polarized transmitted light (see also → isochromatics, → inversion layers, → hot-cold mixture, and → spherulite streaks).

Hot mounting

Thermoplastics or thermosetting precursors (as embedding agents) are heated to the softening temperature of about 150 °C in an embedding machine. The thermoset embedding agents are thereby cured. Thermoplastic embedding agents are cooled in air or water so that they are solid for demolding. The sample is embedded within minutes into a steel mold with great force. Therefore, the process is unsuitable for pressure- and heat-sensitive samples and is thus seldom used (see also → embedding and → plastic materials).

Hot runner

After injection via the sprue into the mold, the molding compound further flows through a hot runner into the mold cavity or through hot runners distributed into the mold cavities. The hot runner stays hot (as the word indicates) through the construction and/or heating, so that the molding compound does not freeze.

HPLC analysis

With HPLC (high performance liquid chromatography) analysis, the quantitative determination of additives with solvents (especially plasticizers) is achieved. For the determination of plasticizers, about 5 mg of sample material is dissolved in a solvent and pressed through a measuring column using pressure (see also → additives and → analysis of plastic materials).

101

Definitions

Technical Terms


Hydrolysis

Technical Terms


Hydrolysis

Hydrolysis is the decomposition of a plastic molding compound at elevated temperature by water, H2O (e.g., hydrolysis of POM from 60 °C).

Illumination

Depending on the type of lighting (illumination) and the contrast method, previously unnoticed striking features of a sample become visible. Usually pure or filtered halogen light is used for the various types of lighting in reflected and transmitted light. The contrast methods work with or without color filter, polarizer, DIC prism, or lambda plate or with combinations thereof (AL-HF, AL-DIC, AL-DIC + , AL-DF, AL-FL, AL-PH, AL-POL and AL-POL +  and DL-HF, DL-DIC, DL-DIC + , DL-DF, FL-DL, DL-PH, DL, and DL-POL-POL +  ).

Definitions

Polarized incident or transmitted light with a polarizing filter is not colored but can be colored with a lambda plate (-plate). A blue filter produces blue light with a shorter wavelength  and higher resolution than pure halogen light. Microcracks sprayed with fluorescent agents are visible in UV light. For DL-HF, DF-DL, DL, and DL-FL-PH, no DIC slider or lambda polarizing plates are used. The aperture and field diaphragm adjust the brightness, depth of field, and contrast. Other types of illumination are one (better) two-armed halogen light source with 150 W (“gooseneck lighting”), for shadow-free illumination also with ring light. The two-armed halogen light source provides a one- or two-sided, high to low standing oblique light with shadows and shows topographies particularly sharply. Centric incident light through the objective also produces a shadow-free illumination. And in the transmitted light method, a folded front lens provides for more brightness. The electron beam (secondary electrons Se) in the scanning electron microscope is also a “type of illumination.” Electrons result in a much higher resolution than light rays (see also → resolution, microscopic, → aperture diaphragm, → incident illumination (Fig. 106), → illumination with reflected light (Figs. 191, 213, 272, 273, 286, 292), → DIC prism, → angle of illumination (Figs. 125, 191), → transmitted light illumination (Fig. 106), → front lens, → halogen light source, → Köhler illumination, → condenser, → contrast, → contrast process, → lambda plate (-plate), → field diaphragm, → microscopy with oblique incident light (Fig. 561), → microscopy contrast with the wrong DIC slider, → microscope parts, → polarizer, → scanning electron microscopy, and → topography). Image resolution

The image sharpness increases with the resolution and contrast, that is, for a high numerical aperture NA of the objective and condenser, “Köhler illuminated” field diaphragm, short wavelength  (blue light), optimal (beneficial) magnification, and high index of refraction n (immersion optics). The cleanliness of the following parts also has great influence: slides, cover glass, objective, ocular, and correct thickness of cover (see also → aperture, → aperture diaphragm, → resolution, microscopic, → refractive index n, → cover glass, → immersion optics, → Köhler illumination, → contrast, → field diaphragm, → objective, → object slides, → ocular, → magnification, optimal).

Immersion optics

→ Aperture, numerical, → resolution, microscopic

Impact assessment

To do an impact assessment, the molded parts are embedded in the media they will come in contact with later. Therefore, three parts are immersed into differently diluted media with different temperatures and are taken out at various times (see → wetting agent test). After removal from the embedding bath and after drying, the microscopic examination follows in regards to swelling, cracks, and warping (see also → solvent, → media, → wetting test, → cracks, and → warpage).

Incineration

→ Glass fiber breakage

Incipient crack

→ Fracture center

Increase counter‑pressure

→ Extrusion

Influences on quality and costs

Quality requires research and continuous adaptation to demands. Quality is present when all requirements are met and remain that way. Influences on quality and costs are rejects, work climate, design, development costs, production, production type, production control, production quantity, molded parts and machine size, use, design (complexity), handling, production costs, duration of illness, life, labor costs, market analysis, machine, employee concerns (error factors, error rate, salary, health, toxic exposure, skills, lighting, number of employees, motivation, climate, overwork, vacation, and training), the need for he product, value for money, product characteristics (chemical, electrical, mechanical, optical), product quality (required), resource depletion and environmental pollution (often unrecognized costs due to environmental conditions or disasters), as well as advertising and sales (see also → dispersion, → error influences, human, → molding compound temperature, → semifinished part, → cost factors, → type of plastic, → quality influences during extrusion, → quality influences during injection molding, → processing, cold, → pre- and post-treatment, → mold temperature, and → cycle time).

102

Isochromatics



Ingredients

→ Additives, → diffusion barrier, → residue

Inhibitors

Inhibitors delay a chemical or thermal reaction (see also → additives).

Inhomogeneity(ies)

A molding compound with ingredients that are unevenly distributed is inhomogeneous. It then has unequal, distributed over the cross-section, chemical, electrical, or physical properties. Inhomogeneities are, or may cause, for example → additives, → foreign particles, → filler and reinforcing materials, → mass flows, → pigment streaks, and → spherulite streaks.

Injecting

Injection is, in the injection molding process, the filling of the mold with plasticized molding compound. When the injection pressure and the part size increase, the clamping force of the mold increases and the molding compound temperature increases with the flowability (see also → weld line, → injection pressure, → injecting, → injection rate, → molding compound temperature, → core offset, → needle shut-off nozzle, → embossing offset, → residual mass cushion, → webs, → shrinkage, → turbulence, → over-injection, → processing parameters, → mold clamping force).

Injection molding

In injection molding, granulate or powder is fed into the electrically heated cylinder with rotating screw from the hopper, mixed, plasticized, and fed into the collection room before the screw tip. In cooperation, the jacket heating, the friction, and the stagnation pressure cause melting and homogenization of the molding compound. Due to the growing mass cushion, the screw moves back against the stagnation pressure and acts as a piston after switching to stagnation and injection. The discontinuous process is divided into homogenization (plasticization, dosing), injection, holding pressure, and cooling time. The size of the temperatures, times, and pressures determine the part quality (see also → injection, → friction, → homogenization, → cooling time, → jacket heating, → holding pressure, → plasticizing, → plasticizing unit, → quality influences during injection molding, → stagnation pressure, and → cycle time).

Injection molding error (injecting error)

→ Error, rheological, → molding compound rrresssidue, → molded part optimization, → molded part quality, → holding pressure, → holding pressure error, → plasticizing errors, → injection molding, and → over-injection

Injection pressure

→ Injecting, → molding compound temperature

Injection rate

The injection rate is to be selected so that the molding compound rapidly reaches the mold cavities through the flow channels without turbulence and possibly without cooling losses. Cold flow can occur during cooling (see also → injection pressure, → injecting, → injection rate, → molding compound temperature, → cavity, → cold flow areas, → turbulence, and → mold clamping force).

Injection, turbulent

→ Injecting, → turbulence

Insert

An insert is a part that is inserted, and it is usually made of metal. It is inserted into the mold by hand or automatically before the next shot. A typical insert is, for example, a threaded bushing or a shaft bearing made of brass.

Interference

→ Wollaston prism

Internal stresses

→ Molded part stresses

Inversion layer(s)

A starting inversion layer is initially a counter flow layer (molding compound flow) caused by turbulence. It can also flow in the direction of the flowing molding compound. Inversion layers often have a higher temperature than the matrix (or vice versa) and therefore also different shrinkage and stress conditions. They are especially noticeable in semicrystalline molding compounds, as hot-cold streaks (large and small spherulites) with large spherulites in a small spherulitic matrix (or vice versa) and in amorphous plastics after a subsequent coloring. Inversion layers tend to separate through internal and external forces (delamination). They are formed at high injection or transfer pressures. When cold marginal layers mix with the warmer matrix, a hot-cold mixture with large and small spherulites results. Criteria for an inversion layer can be hot-cold streaks (spherulite streaks of different sizes) or pigment streaks (show the reversal of the flow direction) or delamination (see also → delamination, → large and small spherulites, → mass inversion → hot-cold mixture, → hot-cold streaks, and → spherulites).

IR analysis

A thin sample is subjected to IR radiation with the IR spectrometer. The type of plastic can be determined by the characteristic absorption bands found in the IR spectrum. Foreign material and additives can be determined as well.

Isochromatics

Isochromatics (colored lines) are refractions of light of macromolecule orientations (developed in rheological flow processes) that are made visible in polarized transmitted light. Macromolecule orientations can also be cause by molded part stresses. This is why isochromatics will show macromolecule orientations and molded part stresses. They can however only be seen in transparent and translucent molded parts (see also → polarization optics and → polarizing filter).

103

Definitions

Technical Terms

Definitions


Jacket heating

Technical Terms


Jacket heating

The electrical jacket heating heats the cylinder during injection molding and extrusion and keeps the temperature constant, so that the molding compound, after good plasticization and mixing, reaches the correct molding compound temperature (see also → extrusion, → molding compound flow, reduced, → plasticizing, → plasticization unit, and → injection molding).

Jam bushing

→ Extrusion

Knife angle for thin sections

Thin sections should be cut with a low cutting power, that is, with the largest possible declination angles  (40° or more). This is especially true for hard and wide plastic samples. In modern thin section devices, the declination angle is unfortunately fixed and no longer adjustable, because the main customers are mostly medical scientists and they make paraffin sections. A large declination angle improves the lifetime and reduces knife outbreaks, and the thin section does not roll so close together when cutting (coil or “Schillerlocke”). This practical experience was not acknowledged in discussions with various equipment manufacturers (probably for cost reasons). Incorrect inclination angles  and especially dull blades cause thin section compressions. Even high cutting forces encourage this. To determine the optimal inclination angle, longitudinal thin sections of a plastic sample of 20 × 5 mm can be cut with different -angles, until the thin section length is about the length of the block section. The thin section will always be slightly shorter than the block section because of the influences of the inclination angle, the cutting force, and the knife sharpness. Theoretically, the inclination angle for each sample has to be determined again. A constant inclination of 5° is sufficient for good thin sections (based on experience from 35 years in the business and the largest possible declination angle ).

Knives for thin sections

Very rigid blades are used for the production of thin sections. Glass knives have little meaning because of their lower cutting width, lifetime, strength, and somewhat complicated production. Basically, a carbide blade with the cutting type D is preferable. The blade is rigid and stays sharp longer. A steel blade of the same cutting type is less expensive but has a shorter lifetime. Knives with the cutting type C are less desirable because they yield with a hard sample, which creates a thick and thin section.

Köhler illumination (microscope optimization)

The optimization of the microscope is achieved through “Köhler illumination” at M = 100-fold. For Köhler illumination, the eyepiece is first focused on the eye, then the sample, and then the field diaphragm, which is closed to the edge of the image through the height adjustment of the condenser, and then the aperture should be closed to about 30% up to the beginning of a desired effect. As a result, the intermediate image is optimally illuminated, and the field of view, depth of field, sample heating, and flaring are optimized. Note: Close the field diaphragm first, center, focus, and then open again to image size and correct the sharpness again. When performing Köhler illumination in incident light, the eyepiece should be removed, the aperture diaphragm should be centered, and the field diaphragm should be closed, centered, and then opened to the image size (see also → aperture diaphragm, → defective vision, → condenser, → field diaphragm, and → ocular).

Lack of holding pressure

Causes for a partial lack of holding pressure are poor-flowing molding compound masses, when they are cold, highly filled, or reinforced; long flow path in the tool; holding pressure times that are too short; a frozen sprue; a mold temperature that is too low; or an insufficient or missing residual mass cushion in the injection unit, because the screw tip sits close to the cylinder. The sprue often freezes when the mold temperature and/or the molding compound temperature are too low. Then, for shrinkage compensation, no more molding compound from the residual mass cushion can be pressed through (see also → sprue, → molding compound temperature, → holding pressure, → holding pressure error, → holding pressure time, → residual mass cushion, → screw, → shrinkage compensation, → vacuoles and blowholes, and → mold temperature).

Lambda plate (-plate)

The -plate (also Red 1 or gypsum board) itself is birefringent and only has an effect in polarized transmitted light between polarizer and analyzer. The -plate is ineffective without a polarizing filter. It turns brightness values into colors. Here, the path differences in the -plate generate colors and solutions of wavelengths in white polarized transmitted light. The polarizing filter and -plate can only be used in the POL and DIC contrast process. Moreover, the -plate turns the dark image background red-violet during polarization and can thus also recognize, for example, pigment streaks and conglomerates. The -plate turns the polarization contrast to a colored polarization contrast (POL + -plate) and the differential interference contrast to a colored differential interference contrast (DIC + -plate) (see also → DIC prism, → contrast processes in microscopy, and → polarizer).

Laminating

Laminating is the application of a film or multiple layers of film onto a molded part (see also → surface refining).

104

Macromolecules



Large and small spherulites

→ Inversion layers → hot-cold streaks

Laser error

Laser errors are caused by laser pulsations or varying velocity profiles when writing (e.g., increased friction in the laser head guide), increased heat dissipation of the melt low volume in the cold molded part, and gas and particle formation around the laser head (can weaken the laser beam and distract it). Particles and some harmful gases (formaldehyde, chlorinated hydrocarbons, benzene, HCl, etc.) lead, at a high writing speed, to blurred letters, contamination, and corrosion in the environment. A suction avoids this and increases the writing performance up to three times.

Laser writing

→ Laser error, → lasering of letters and numbers

Lasering of letters and numbers

A thin laser beam scans over the molded part while writing and burns letters or numbers into the surface. Here, each letter (or number) is repeatedly run over in a parallel offset way, until readable. However, this is done at least twice as often in crossing points, which can result in a bad typeface, because there the input of energy is greatly increased.

Layer displacement

→ Delamination

Layer formation

→ Coating, → delamination, → electroplating, → laminating, → painting, → laminating, → marginal zone for amorphous plastics, → marginal zone for semicrystalline plastics, and → marginal zone, poor in spherulites

Layer thickness

The measurement of film thickness is made in 10 micron thin sections or polished samples. When cutting, decreasing blade sharpness causes a growing transverse contraction of the thin section and prevents the accurate determination of layer thickness in the microscope. Therefore, it is better to measure the remaining polished samples because there the true thicknesses are still present (unchanged).

Lens barrel

→ Microscope

Level of gelling

The level of gelling indicates the maximum degree of partial melting in percent. It should be approximately 60 to 70% after a PVC extrusion and is determined by OSCD analysis. During welding of window profiles, the level of gelling can rise so high that the weld lines become brittle with further temperature loads (see also → OSCD analysis).

Light field diaphragm

The field diaphragm controls the interframe illumination, the size of the field of view, depth of field, and sample heating. They prevent contrast-reducing stray light and hide optically uncorrectable lens margins (overexposure). Thus, the depth of field is improved. The field diaphragm sits in the hatch optical path and can be sharply seen in the image at a correct condenser setting (Köhler illumination). The following sequence applies in incident light: lamp–aperture diaphragm–field diaphragm, and in transmitted light: lamp–field diaphragm–aperture diaphragm (see also → aperture diaphragm, → Köhler illumination, → hatch optical path, and → optical path of the pupil).

Light microscope LM

→ Microscope (light microscope)

Light stabilizers

Added light stabilizers protect the plastic surfaces from light and UV effects and color changes (e.g., fading) by absorption. Also lightproof pigments such as titanium dioxide and carbon black pigments act protectively.

Light, polarized

→ Polarized light

Lighting

→ Illumination

Link chain

Pipes are removed during extrusion using a link chain, so that the pipe, which is still plastic when it exits the extruder head, is not compressed and is cooled in a water bath (see also → extrusion).

LM

LM is short for light microscope (see also → microscope)

Lubricant (internal and external)

There are internal and external lubricants (such as waxes). They improve the processing of plastics in the processing machinery and produce for example smooth surfaces during extrusion molding.

Macromolecules

Macromolecules consist of at least 1000 monomers, connected by chemical bonds (main valence forces). A molded part in turn consists of countless macromolecules (macromolecule chains), which are held together by intermolecular attraction forces (secondary valence forces) (see also → main valence forces and → secondary valence forces).

105

Definitions

Technical Terms

Definitions


Macro- and microscopic examination

Technical Terms


Macro- and microscopic examination

→ Macroscope, → microscope, and → microscopic examination.

Macroscope

The preliminary examination in the macroscope is often a perfect answer to the quality or source of damage. If not, the main examination follows, after sample preparation, under a microscope at M = 30–500-fold, of the details that were recognized under the macroscope. A macroscope (stereomicroscope) should have equipment for quality and failure analysis such as a stereomicroscope with field glass principle (essential for multifocus shots), and magnification of about 5 to 30 times and, after a lens change, to 100-fold. Supplementary lenses and post-enlarging oculars do no create good image quality. The most effective types of contrast are incident AL and transmitted light DL with polarizing filter POL and lambda plate (-plate), as well as incident and dark field contrast AL-DF. Recommended accessories are moving stage, two-armed halogen light source 150 W with ring light, adapter for photo and video camera, photo camera, three-chip video camera, multifocus device, software for PC image exposure, and a color laser printer to print images (see also → image resolution, → field glass principle, → Greenough principle, → halogen light source, → main investigation, → contrast process of microscopy, → microscope (universal microscope), → microscopic examination, → microscope parts, → multifocus, → sample preparation, → stereomicroscope, → depth of field, → examination devices, microscopic, → examination, comparing, and → preliminary examination).

Magnification

The magnification VM = VOB · VOK achieves values of up to 4000-fold in light microscopy. For plastic samples, enlargements up to 500-fold are common. The reason is the low depth of field of microscopes. It decreases rapidly with increasing magnification. Thin section and thin ground sample preparations must therefore be plane-parallel to the slide. This also applies to block ground samples and polished samples. They should not have any topography if possible (without “peaks and valleys”). The theoretical resolution is about 0.16 microns; the practical is only 0.3 microns to 1.5 microns. The depth of field is already, at 200-fold magnification, so low that a scalp hair (over its entire diameter) is no longer in focus. The magnification should not be increased with post-magnifying oculars, especially if the numerical aperture NA of the objective is small and does not provide sufficient pixels. A high post-magnification with insufficient resolution only provides blurred images. The optimal magnification is calculated using the following rule: VM ≈ 500 · NA to 1000 · NA. NA = numerical aperture, VOB = magnification number of the ocular, and VOK = magnification number of the objective

Magnification number

The magnification number is the magnification of the objective and ocular (see also → magnification and → aperture, numerical).

Magnification, optimal

→ Magnification

Main inspection, microscopic

The main microscopic examination is performed in a universal microscope at about 30 to 500 times magnification, usually after a visual and microscopic preliminary examination. For an examination, specimens are taken from the conspicuous areas of the preliminary examination using appropriate preparation equipment and preparation techniques. The main investigation can also be done directly with known or other striking features from the preliminary examinations or after any necessary pretreatment with preparation agents. Such striking features include aging, weld lines, fracture types, fractures, thickness measurements of paint layers, laminates films and panels, molding compound overheating, molded part dimensions, foreign material (regranulate), fillers and reinforcing materials, cold-flow areas, conglomerates, blowholes, matrix adhesion (better in SEM), media attack, surface defects, pigment dispersion, pigment inks, polymer blends (better in SEM), cracks, shear orientations, layer thickness (on thin sections or polished samples), melting processes (melting stage), welds, shrinkage, stress and notch effects, marginal zones lacking in spherulites, spherulite size, spherulite distribution, and vacuoles. Different contrast methods may be used for a clear illustration of the striking features (see also → molded part errors, → contrast processes, → macroscope, → microscopic examination, → multifocus, → preparation devices, → preparation agent, → preparation techniques, → marginal zone for amorphous plastics, → marginal zone for semicrystalline plastics, → marginal zone, poor in spherulites, → universal microscope, → examination, visual, and → preliminary examination).

Main valence forces

106

Main valence forces are the chemical bonding forces of the molecules and macromolecules (such as C–C bond, see also → secondary valence forces).

Material residue transfer



Marginal zone of amorphous plastics

Amorphous plastics get marginal zones in cold molds, but they are usually not visible. In hard plastics, an intentionally produced violent fracture shows the thickness of the marginal zone at a 45° outgoing fracture edge or boundary layer separation (see also → marginal zone in semicrystalline plastics, → plastic materials).

Marginal zone of semicrystalline plastics

The thicker the marginal zone, which is low in spherulites, the colder was the mold and/or molding compound temperature in a fast injection. With a 10-micron thin section, the marginal zone, which is low in spherulites, is mostly easily measured at 100-fold magnification and normally reaches a thickness of up to about 100 microns. If it is exceeded, the mold temperature was usually too low. A higher magnification may complicate a thickness determination, because a blurry small-spherulitic transition area is often observed in the marginal zone. Therefore, an increase in the range of 50- to 100-fold is recommended (see also → marginal zone in amorphous polymers, → plastic materials, → mold temperature, and → vacuoles and blowholes).

Marginal zone, poor in spherulites

Marginal zones, which are low in spherulites, occur at the colder mold surface and are only visible in semicrystalline plastics. Amorphous plastics also get marginal zones, but are usually not visible. Generally speaking, the colder the mold, the greater the marginal zones of amorphous and semicrystalline plastics (see also → marginal zone for amorphous plastics, → plastic materials, and → vacuoles and blowholes).

Mass accumulation

The term mass accumulation points to a larger plastic volume, which has a distinct shrinkage tendency when cooling the mold. A mass accumulation, which occurs, for example, in the transition to ridges (ribs), preferably causes stresses and vacuoles. Therefore, the wall thickness there (constructively) should be as small as possible.

Mass flows, leading

→ Weld line

Mass inversion, with and without induction

A mass inversion (without air induction) is a reversal of the flow front. It develops, for example, when the molding compound bonds with molding compound that is flowing back from the end of the mold. This happens especially in turbulent filling, stream formation, or high injection rates when different (at different injection rates) same- or counter-direction mass streams meet each other and bond (Figs. 99–102). In the area of the molded part surface, air can also be drawn in and a mass inversion with air induction often occurs close to the sprue (Figs. 231 and 269) through the turbulence of already cooled molding compound (from the wall) with hot molding compound (from the plastic core). The molding compound, which is still very warm, is swirled at the colder mold wall, draws air in, and can then (being highly viscous) only poorly or not at all bond. This error even occurs with an inadequate mold venting. Demolding and detergent agents from injection molding or other media preferably penetrate there and into other weak points, such as in weld lines and cold flow areas (see also → weld line, → reversal of the flow front, → hot-cold streaks, and → inversion layer).

Mass stream, free

A free mass stream is a wormlike strand in the molded part surface or in the molded part. Remedy: The free-jet formation is, for example, prevented by a transfer of the section or when injection is done against a baffle (baffle pin) or wall.

Mass temperature

The mass temperature is the temperature required for melting and homogenizing of the molding compound (see also → molding compound temperature, → molded part quality, → jacket heating, and → injection molding).

Masterbatch

A masterbatch is a color concentrate (granulate) with 30 to 50% amount of color in a plastic material that also corresponds to the molding compound to be colored. By its granular form, a masterbatch is easier to homogenize than powder or liquid paint. Unsuitable masterbatch carrier results in reduced molded part strength and pigment streaks (see also → molded part strength and → pigment streaks).

Masterbatch carrier, If a thin section has pigment conglomerates higher than 80 microns, a mixed-up masterbatch or an unsuitable masterbatch carrier may be present (see also → masterbatch). unsuitable Masterbatch change A masterbatch change or rebatching is always present when a molding compound delivery (masterbatch) which is not from the same manufacturing date, with the same, proven quality, is processed. This also (rebatching) applies when only one ingredient in its concentration or quality has been changed, such as an additive, the color, or type of pigment (see also → additive). Material residue transfer

A material residue transfer occurs when, after demolding in the mold, a molding compound particle (material) gets stuck and is over-injected with molding compound in the following shot and is then embedded, flat or recessed, into the surface. An over-injection is present when the molding compound particles protrude through the molded part surface (see also → transmission of the bath, → shot sequence, → cold plug, → particles, and → over-injection).

107

Definitions

Technical Terms


Matrix


Matrix

The matrix is a surrounding molding compound of, for example, filler and reinforcing materials. For example, glass fibers must be completely wetted by the matrix (molding compound) for force transmission and embedded in it, which means that they need to have a good matrix adherence. Generally, the term matrix means molding compound with all additives such as additives, filler, and reinforcing materials (see also → additives, → filler materials and reinforcing materials, and → structure study).

Matrix bonding

→ Matrix

Matrix degradation

→ Aging and → decomposition, thermal

Matte spots

→ Shape stains and matte spots

Measure migration

→ Migration

Measure oxidation

→ DSC analysis

Measure residues

→ ESCA analysis and → analysis of plastic materials

Measuring plate

→ Ocular

Media attack

A media attack first produces net-like cracks in the highest stress areas of the molded part surface under the influence of temperature and time by fats, oils, wetting agents, solvents, and ionizing radiation. Polyolefins (PE, PB, and PP) are already being attacked by copper in an aqueous environment (copper attack). If cracks are developing close by, instead of inside the weld line, it indicates a media attack. Although weld lines are particularly notch-sensitive with V-shaped surface indentations, if cracks appear close by, media cracks that can cause stress cracking are acting in dynamic exciting transition areas (see also → aging, → weld line, → weathering, artificial, → notch effect, → solvent, → media, → media influences, → media cracks, → media streaks, → wetting agent, → wetting test, → marginal zone for amorphous plastics, → marginal zone for semicrystalline plastics, → marginal zone, poor in spherulites, → cracks, → streaks, → shrinkage, and → stresses.

Media cracks

Media cracks preferably develop in the area of stress peaks due to exposure to media, which can cause stress cracking under the influence of time and temperature. The medium attacks the plastic surface at the point where the temperature and stress are greatest. Depending on the type of plastic and aggressiveness, the medium diffuses a few hundred microns deep into the surface of the molded part surface, and it weakens the secondary valence and then the main valence forces through inner and outer molded part stresses. Sometimes a medium only causes swelling in the plastic, but its gas phase acts strongly crack-actuating. The amorphous region is basically always attacked first because the semicrystalline region has a higher binding energy. After exceeding the critical stress, brittle fractures often occur in atypical areas (for example, near the weld line) accompanied by net-like surface cracks. Here, the fracture edges can show plastic deformation, and the fracture environment can show patchy, drop-like, greasy, oily, or liquid residues. The flank cracks are mostly glassy smooth and have no or rare rupture flank cracks (see also → fracture, → molded part stresses, → solvents, → macromolecules, → media, → media attack, → media influences, → media cracks, → media streaks, → secondary valence forces, → wetting agent, → residues, and → plastic deformation).

Media influence

Media influences include, for example, solvent evaporation, chemicals (acids and bases produce swelling and degradation), energetic radiation (UV, -, -, -radiation), temperature elevation, changes in temperature, humidity (residual moisture), and ozone (see also → degradation, → aging, → media, → media attack, → media influences, → media cracks, → media streaks, and → residual moisture).

Media streaks

The causes of media streaks are chemicals that dissolve the plastic surface, leaving rough, dull, strip-like areas after drying (see also → media, → media attack, → media influences, → media cracks and streaks).

Media that can cause stress cracking

Media that can cause stress cracking can cause stress crack formation (environmental stress cracking ESC). Media cracks develop in the plastic surface after a short exposure time, and internal cracks can develop after a long exposure time. These cracks are a proof of outer surface tensions or internal stresses. Therefore, a solution, which is appropriate to the type of plastic, is started and the molded parts are submerged in it for 5 to 15 minutes. The sooner cracks occur, the higher the external molded part stresses. For the detection of internal molded part stresses, however, heat exposure at the level of the glass transition temperature is much more suitable. Caution: the swelling hides cracks, therefore it is recommended to let the molded parts dry overnight (storage under standard conditions DIN 50014) after removal. Media that can cause stress cracking for plastics are:

Definitions

Technical Terms

From worksheets from the following companies: BASF, Bayer, Höchst See also DIN ISO 175, ISO 4600, ISO 6252

108

DIN EN ISO 1133, ASTM 1238 Technical Terms Media that can cause stress cracking (continued)


Explanation of Terms Toluene + n-propanol 1 : 3–1 : 5, 80% acetic acid, methanol

ASA

Olive acid + oleic acid 1 : 1

PA6

Zinc chloride 35% (soldering fluid) acetone

PA6.6

Zinc chloride solution, 50%, 15–60 min at 50 °C

PA6-3

Acetone, methanol, isopropanol

PBT

Zinc chloride solution 50%, caustic soda

PC

Toluene + n-propanol 1 : 3–1 : 10, methanol, 5 min

PC/ABS

Toluene + n-propanol 1 : 3, methanol + ethyl acetate 1 : 3

PE

Surfactant 5%, 1 to 48 h at 70–80 °C

PEEK

Acetone, 1 h

PEI

Methyl ethyl ketone

PESU

Ethyl acetate, toluene, methyl ethyl ketone, 1 min

PMMA

Toluene + n-heptane 1 : 2, ethanol, N-methylformamide

POM

Sulfuric acid 50%, phosphoric acid 75%, 3 min at 50 °C

PP

Chromic acid 40–50 °C

PPE

Methanol + trichlorethylene 2 : 1, tributyl phosphate

PPO/PS

Tributyl phosphate, 15 min

PS

Toluene + n-propanol 1 : 3–1 : 5, 1 to 10 min, acetone vapor

PSU

Acetone, ethylene glycol monoethyl ether, trichloroethane

PVC

Methanol

PVDF

Caustic soda

SAN

Toluene + n-propanol 1 : 5–1 : 10, ethanol

SB

n-heptane, petroleum/benzene, olive acid + oleic acid 1 : 1

Definitions

ABS

(See also → molded part stresses, → glass transition temperature, → solvents for plastics, → media attack, → media cracks, and → wetting test.) Melting temperature range

→ DSC analysis

Metal abrasion

Metal abrasions are particles from containers, feeding pipes, filling hoppers, mills, screws, diving nozzles, and cylinders. Remedy brings abrasion protection (armor), for example by applying a surface welding of highly abrasive metals on the metal surfaces.

Metal analysis

Many pigments and stabilizers contain metals, often even heavy metals, the use of which is strictly regulated in toys, food packaging, and medical devices. The content of metals like lead, cadmium, zinc, and chromium in plastics and recycled materials can be determined by atomic absorption spectroscopy. The detection limits are in the ppm or ppb range, depending on the metal (see also → stabilizers).

Metal particles

→ Particle

Metallizing

→ Electroplating

MFR analysis (MFR value)

The flow behavior and the thermal and mechanical degradation of plastics is determined with the melt index MFR (melt mass-flow rate). The MFR value is the amount of plastic compound, in g/10 min, that flows through the standard nozzle in 10 minutes. The required sample size is approximately 5 g, and the melt temperature is dependent on the polymer. The macromolecule length and strength of a molded part decreases with increasing MFR (e.g., strong for perfluoroalkoxyalkane PFA). A FTIR spectrometer (IR spectrometer) with an attached microscope at the MFR apparatus (both having ATR units) is needed in order to perform a point analysis. Without pretreatment, surfaces can be directly examined, and the chemical structure, the type of plastic, and the smallest particle (e.g., additive) can be determined (see also → ESCA analysis, → type of plastic material, → analysis of plastic materials, → MVR value, and → residue).

DIN EN ISO 1133, ASTM 1238

109

Definitions


Microscope (light microscope)

Technical Terms


Microscope (light microscope)

Microscope is a term for various types of optical/light microscopes that use incident and transmitted light, such as the universal microscope and macroscope. Light microscopes are used for quality and damage analysis on molding compounds, semifinished parts, and molded parts in incident and transmitted light with different contrast processes, with and without filters (see Figs. 104 to 107). Objects that cannot be recognized with the eye (crazes, filler materials, pigments, spherulites, etc.), are examined under the microscopes. In principle, a microscope consists of two magnifying systems, the objective and ocular (eyepiece). The first magnification in the objective passes through the tube lens as a real intermediate image (aerial view) into the intermediate image plane, the ocular (second magnification), and as a virtual image to the retina. Incidentally, the real intermediate image is also visible without the ocular with the focusing screen, which is inserted into a tube or directly from a distance of 25 cm. The microscope also has the task of greatly enlarging structures that are no longer recognizable. For plastics, the limit of useful magnification is 500-fold (see also → achromatic lens, → color filter, → devices, → Köhler illumination, → condenser, → contrast, → macroscope, → microscopic examination, → microscope parts, → Neofluar lenses, → objective, → ocular, → plan apochromatic objective, → polarizer, → scanning electron microscope, → stereomicroscope, → depth of field, → universal microscope, and → magnification).

Microscope optimization

To optimize a microscope, the following actions are required: 1.

The eyepiece distance should be set to interpupillary distance. Both eyepieces should be held like binoculars and should be opened and closed until the double edge of the visual field turns into a round circle (see also Fig. 105).

2.

A dioptric compensation on the focus ring on the eyepiece should be performed for defective vision (until the measurement plate or reticle is clearly visible, see also Fig. 105).

3.

Illumination and contrast processes should be chosen correctly. The color of light influences the resolution, and the contrast method affects the visibility of striking features of the sample (see also → color filter).

4.

The sample should be focused by changing the working distance between the sample and lens (see Fig. 107).

5.

The field diaphragm should be closed up to the edge of the field of view (Fig. 104).

6.

The aperture diaphragm should be slowly closed until an optimal visibility of the damage occurs (Fig. 104).

7.

Köhler illumination is achieved through a height adjustment of the condenser (see also → Fig. 107 and → Köhler illumination).

8.

The cleanliness of cover glass, lenses, and slides is very important.

9.

Dark, blurry spots in the field of view indicate a contamination in the microscope, and sharp ones indicate contaminations on the lens from the outside or in the intermediate image plane (measuring or reticle). Cleaning of the outside of the microscope is usually achieved well, but of the inside more rarely.

10. Microscopy also requires breaks. With decreasing concentration, it is necessary to take a break so that no striking features are overlooked. 11. Disinfection of the eyepieces and eyecups should be performed if possible every day, particularly when different users are on the same microscope. See also Figs. 104 to 107. Microscope parts

110

Microscopy is associated with devices and elements: → achromatic lens, → analyzer, → aperture, → aperture, numerical, → aperture diaphragm, → resolution, microscopic, → eye, → illumination, → diffraction angle, → visual awareness region, microscopic, → image resolution, → refractive index, → cover glass, → DIC prism, → bright field dark field slider, → color filter, → defective vision, → field glass principle, → fovea, → Greenough principle, → halogen light source, → main examination, → immersion optics, → camera switch, → Köhler illumination, → condenser, → contrast, → combine contrast processes, → contrast processes, → conversion filter, → cross table, → lambda plate (-plate), → field diaphragm, → hatch optical path, → macroscope, → measuring plate, → microscope, → microscope optimization, → multifocus (device), → Neofluar lenses, → objective, → objective revolver, → object micro meter, → object slides, → ocular, → plan apochromatic objective, → polarizer, → preparation devices,

Microscopic examination


Technical Terms


Microscope parts

→ preparation agent, → sample preparation, → sample focusing, → sample table, → optical path of the pupil, → scanning electron microscope, → Rayleigh criteria, → sickle aperture, → blocking filter, → sputtering, → stereomicroscope, → beam splitter, → scattered light, → reticle, → depth of field, → topography, → tube, → tube lens, → universal microscope, → examination, comparing, → examination devices, microscopic, → magnification, → magnification, optimal, → magnification number, → visual examination, → preliminary examination, → Wollaston prism. See also the following Figs. from 104 to 107:

(continued)

Fig. 104 Universal microscope (magnification = 1 : 1) in transmitted light with aperture diaphragm (5), condenser (in 5), field diaphragm (7), object revolver (1), polarizing filter (6), sample table (2) Fig. 105 Universal microscope (photo) in transmitted light with bright field dark field slider (3), camera switch (5), conversion filter (7), field diaphragm for incident light (6), object revolver (1), polarizing filter (4), sample table (2) Fig. 106 Universal microscope with aperture diaphragm (7) in incident light, incident light illumination (9), transmitted light illumination (10), field diaphragm for incident light (6)

See also → microscopic equipment, → microscopic examination, → polarizing optics, and → examination devices, microscopic. Microscopic equipment

→ Preparation devices and → examination devices, microscopic (see also Fig. 103 and → microscope parts)

Microscopic examination

A microscopic examination is performed to assess and document the sample quality by increasing the areas to be examined under a microscope. Procedure: After a → customer inquiry over the phone with an exact offer discussion by skillful → questions for the customer, he/she receives a written offer. Once the written confirmation is present, the examination may start. A → sample preparation (for LM or SEM samples) is often necessary as well as an appropriate → preparation agent, → preparation techniques, as well as → preparation devices. This is followed by a visual and microscopic → preliminary examination, with electronic image capturing and archiving. After any subcontracting (→ subcontraction), the microscopic → main examination follows, also with image capturing and archiving. During microscopy, the specimen should be thoroughly examined after a → microscope optimization in → visual awareness region scan, namely from the perspective of the plastic (→ plastic behavior, understanding). Important are the choice of → illumination and → contrast method, and the combination in rare cases (→ combine contrast processes) as well as the knowledge of the microscopic → examination devices and their parts (→ microscope parts). Any irregularity should be documented with a picture and descriptive text, as a picture is often better than just text alone. Even the image caption should be immediately listed and logically numbered. Parallel to the microscopic evidence deepening results, physical and thermal analyses are performed if necessary (→ microscopy accompanying research). The biggest influence on the → molded part quality are the machine, the human (→ error influences, human, → influences on quality and cost), the → processing parameters (→ molded part error), but also → packaging and transportation. As an expert, you have collected machinery, product, and quality catalogs (reference books) and have them “in your head” along with a catalog of errors. The manufacturing process, the operation sequences, the processing parameters, and the errors of a sample (abnormalities) can therefore be already recognized in a visual and microscopic examination. Together with the skillful questions for the customer as to environmental influences during production, packaging, and transport, you can then advise and write a report (→ report, → report preparation, fast and competent). You do not even need to know the latest type of machine, just the exact work sequences and its effects. With the recognized technical term (the term of the striking feature of a sample), the figure number can be found in the chapter → technical term glossary, the corresponding figure with figure text can be found in the chapter → quality and damage figures, and the explanation can be found in chapter → definitions. More information can be found under → customer loyalty, → novice terms, and → gain of time in expert opinions.

111

Definitions

Fig. 107 Universal microscope in transmitted light with aperture diaphragm (5), rotary knob for sample focusing (3), field lens folded out (11), condenser height adjustment for Köhler illumination (12), field diaphragm (7), polarizing filter (6), sample table-height fixation (13), and centering screws for the field diaphragm (14)

Definitions


Microscopy accompanying research and work

Technical Terms


Microscopy accompanying research and work

Further examinations and operations are done by microscopic examination to secure and supplement information on → aging, → wetting test, → report, → weathering, artificial, → influences on quality and costs, → error influences, human, → gloss measurement, → determining the glass-fiber length, → pinking test, → adhesive tape test, → analysis of plastic materials, → solvent tests, → sample preparation, → residual moisture, → clamping block method, → stress crack test, → tempering, → examination, comparing, and → embrittlement (see also → microscopic examination).

Microtome (thin section equipment)

→ Thin section device

Microvacuole(s)

A microvacuole is a jagged shrinkage cavity. It is caused by a partial lack of holding pressure, when the holding pressure cannot press enough molding compound from the residual mass cushion through for shrinkage compensation. A microvacuole is often difficult to see in a glass-fiber reinforced fracture surface because torn glass fibers leave holes that may be confused with microvacuoles. To be on the safe side, it is recommended to always make polishing touchups. (see also → residual mass cushion and → vacuoles and blowholes).

Migration

During migration, plastic content migrates to the surface of a molded part (pigments, additives) and produces colored spots (residue). A well-known example is the migration of plasticizers. Monomeric plasticizers are oily substances. They can cause cracking in other plastics, in particular at an air content of 5 to 10%. A similar process to migration is efflorescence with chalky or sticky spots (see also → efflorescence, → HPLC analysis, and → residue).

Moisture in the molding compound

Most plastics have to be dried (predrying) before injection molding or extrusion to prevent formation of moisture streaks, voids, and bubbles. Some plastics, such as polycarbonate and polyoxymethylene POM PC, are susceptible to hydrolysis. It means that its macromolecular chains degrade under the influence of moisture from about 60 °C. In particular, PC reacts with brittle fracture to poor or missing predrying (see also → bubble formation, → moisture streaks, → vacuoles and blowholes, → macromolecules, → residual moisture, → embrittlement, and → predrying).

Moisture streaks

Moisture streaks open in a V-shape in the flow direction. The cause is high residual moisture of the molding compound due to poor or missing predrying (see also → moisture in the molding compound, → residual moisture, → streaks, and → predrying).

Mold breathing

→ Mold clamping

Mold clamping

If the mold closing force or mold clamping force is not sufficiently large during injection of the molding compound, the mold is impressed. Then, the mold separation can open and the exiting molding compound forms a web through mold breathing (see also → injection, → webs, → mold breathing, and → mold clamping force).

Mold closing force

When the injection pressure, the molded part size, and flowability increase, the mold closing force and the flowability of the molding compound with molding compound temperature increase as well. The mold closing force (mold clamping force) is calculated from the projected area of the molded part contour multiplied by the injection pressure (see also → weld line, → injection pressure, → injection, → injection rate, → molding compound temperature, → core offset, → needle shut-off nozzle, → embossing offset, → residual mass cushion, → webs, → shrinkage, → turbulence, → over-injection, → processing parameters, → mold synchronization (filling study), → mold breathing, → mold filling, → mold separation, and → mold offset).

Mold filling, poor

→ Molded part quality

Mold impression

→ Molded part quality

Mold offset

A mold offset arises through worn-out mold guide pins. Then the mold halves no longer close precisely, which leads to a molded part offset (see also → molded part offset, → core offset, → and webs).

Mold overfilling

→ Over-injection and → mold filling, poor

Mold resistance

→ Extrusion

Mold separation

With an injection mold, the mold separation is the area where mold surfaces touch during opening and closing (formerly → parting plane).

Mold synchronization

→ Filling study

112

Molding compound flow, reduced


Technical Terms


Mold temperature

The mold temperature should be as high as possible, so that the injected molding compound reaches the most distant cavities easily. The cause of innumerable cases of damage is often a mold temperature that is too low because it affects the cycle time and is therefore intentionally set low or too low. Damage costs through recalls, expert opinions, and image loss are usually much more than the supposed cooling time gain brings. The mold temperature is regulated to a constant temperature with a temperature controller and should be the same in the mold halves and all mold cavities The temperature level must allow for optimal mold wetting. The damage cause was mostly the mold temperature, which is too low in about 80% of all the damage claims–to reduce cycle time and cost savings? The injected molding compound cools very rapidly at a mold temperature that is too low. This results in molded part stresses and poor quality of the molded part and a cold flow (see also → molded part quality, → injection molding error, → molding compound temperature, too cold, → molded part stresses, → report preparation, fast and competent, → cold flow, → post-crystallization, → injection molding, → mold filling, and → cycle time). → Mold temperature

Mold ventilation, insufficient

→ Ventilation, insufficient

Mold venting

→ Venting

Molded part embrittlement

→ Embrittlement

Molded part error

→ Molded part quality, → molded part stresses, → quality influences during extrusion, → quality influences during injection molding

Molded part impression

→ Molded part quality and → mold temperature

Molded part optimization

→ Quality influences during extrusion, → quality influences during injection molding

Molded part quality

Demolding errors develop in the part surface through poor mold filling. The injected molding compound can then not completely fill the cavitation in the mold (poor impression). Causes include a reduced molding compound flow at too low mass, mold, and or molding compound temperature, a too-slow injection speed or a too-low injection pressure and holding pressure (see also → injection pressure, → injection speed, → venting, → molding compound flow, → molding compound temperature, → cold flow, → cavitation, → mass temperature, → holding pressure, → needle shut-off nozzle, → orange skin, → webs, → mold impression, → mold adjustment (filling study), → mold breathing, → mold venting, → mold clamping force, → mold temperature, → mold separation, → mold overfilling, → mold offset, → mold resistance (extrusion), → mold clamping, → quality influences during extrusion, and → quality influences during injection molding).

Molded part quality when extruding or injecting

→ quality influences during extrusion, and → quality influences during injection molding

Molded part seam

The molded part seam is an impression of the mold separation (mold opening) on the molded part (see also → burr and mold separation).

Molded part strength

The molded part strength is influenced by → weld line strength, → delamination, → dispersion, → coloring, → injection pressure, → color pigments, → error, rheological, → reversal of the flow front, → molding compound, reinforced, → molding compound temperature, → molded part stresses, → foreign particles, → filler materials and reinforcing materials, → mass inversion, → glass fibers, → homogenization, → cold flow, → core offset, → design error, → masterbatch carrier, unsuitable, → holding pressure error, → nanofillers, → pigment streaks, → tempering, → ultraviolet radiation, → reinforcing materials, → pre- and post-treatment, → mold temperature, and → cycle time).

Molded parts

See also → semifinished part

Molded part stresses

→ Stresses in the molded part

Molding compound flow, reduced

Determine → molding compound, flow behavior

113

Definitions

Mold temperature, too cold

Definitions


Molding compound residue transfer

Technical Terms


Molding compound residue transfer

Molding compound residue transfer occurs when molding compound particles from the previous shot that are adhering in the mold are over-injected in the following shot (see also → following shot).

Molding compound temperature

In injection molding, the molding compound temperature is determined by friction during plasticizing through dynamic pressure, screw geometry, screw speed, and mantle heating so that the molding compound in the thermoplastic range enters (easily flowing) into the mold cavities. The injection pressure forces the plastic molding compound (the shot weight) into the closed mold after homogenization. It affects the injection speed and must be selected so that no turbulence, high friction, or mold breathing can occur. Influences on the weld line strength, burrs, mechanical strength, surface quality, and warpage are the injection pressure, injection speed, molded part size, plastic quality, molding compound, and mold temperature and cycle time. During extrusion, the molding compound is plasticized and melted. This is achieved under the thermal influence of the electric jacket heating, the friction heat during homogenization, and the counter-pressure of the perforated disc and screen packs. Here, the screw geometry and screw speed are chosen so that the molding compound in the thermoelastic area enters the cooling water bath (see also → weld line, → injection rate, → extrusion, → molding compound, → molding compound, cold, → friction, → counter-pressure, → homogenization, → homogenization, poor, → jacket heating, → mass temperature, → surface quality, → plasticizing unit, → plasticizing, → screw, → injection molding, → burr, → stagnation pressure, → turbulence, → warpage, and → cycle time).

Molding compound temperature, too-cold

At a too-cold molding compound temperature, the molding compound becomes slow moving and produces molded stress and cold flow, as well as a poor quality of the molded part in the mold (see also → molded part quality, → molding compound flow, reduced, → molded part temperature, → molded part stresses, → cold flow, → orange skin, → mold filling, → mold temperature, and → mold temperature, too cold).

Molding compound, cold

Consequences and causes of a cold molding compound can be seen under → molding compound flow, reduced, → molding compound temperature, → molding compound temperature, too cold, → granulate, unmelted, → cold flow, → residual granulate, → injection molding, and → mold impression.

Molding compound, flow behavior

The flow behavior of the molding compound in the mold can be recognized in a stress test after the removal of the complete runner with all mold cavities. The runner is dipped into a wetting agent and examined microscopically, for example, after 15 and 120 min at 10-fold magnification. If high internal and surface stresses are present, significant deformations can be seen on the surface after 15 min and cracks are visible, but often only on some cavities. This then proves an uneven flow behavior of the molding compound in the mold. The cracks are only recognizable after a decrease of swelling, which is after about 120 min of evaporation of the wetting agent. If all cavities show deformations or cracks, causes are: the mold temperature is too low, the sections are too small, the injection speed is too slow, and the holding pressure and possibly also the mold venting is too low. If only a few cavities have deformations or cracks, the mold temperature and/or the holding pressure are unequally effective: they only have a few cavities. Remedy: Increase the sections, improve ventilation, and check tempering channels. Molded part and surface stresses develop through poor flowability of the molding compound, when the mold and molding compound temperature as well as the holding pressure are low and thus a high flow resistance is present. In injection molding a reduced molding compound flow results from a too-low injection speed, too low melt and mold temperatures, lower injection pressure, long flow paths, narrow cross-sections, a too-slow filling of the mold, bad mold venting, a core flowing, design errors (gate or wall thickness is too small), as well a high glass fiber content above 40%. Then microvacuoles and vacuoles often form in the molded part. During extrusion, a reduced molding compound flow results when the extrusion speed, melt temperature, screw speed, mold temperature, or the counter-pressure is too low (see → holding pressure). See also → sprue, → runner, → section, → weld line, → deformation, → injecting, → injection, turbulent, → injection rate, → reversal of the flow front, → flow lines, → weld line, → examine the flow behavior, → molding compound, cold, → molding compound, previously colored, → molding compound, reinforced, → molding compound temperature, → molding compound temperature, too cold, → molding compound residue transfer, → cavity, → filling study, → glass fibers, → design error, → plastic materials, → plastics, semicrystalline, → media that can cause stress cracking, → microvacuoles, → counter-pressure, → wetting test, → shearing, → injection molding, → vacuoles, → viscosity, → mold venting, poor, and → mold temperature.

114

Object slides



Molding compound, previously colored

A molding compound is a granulate or powder provided by the suppliers of raw materials. Powder though is used less and less. A previously colored molding compound is a molding compound that is already colored by the raw material suppliers (see also → coloring, subsequent, → molding compound, cold, → molding compound, reinforced, and → injection molding).

Molding compound, reinforced

Addition of glass fibers, glass pellets, or minerals results in a reinforced molding compound with modified properties, adapted to the particular use. The flow properties of the molding compound usually decreases with the degree of filling (amount) of the admixture (see also → filler materials and reinforcing materials, → extrusion, → injection molding, and → reinforcing materials).

Monomer

A monomer (molecule) is the smallest chemical component of a → macromolecule.

Multifocus

A macroscope cannot focus on big differences in height (topography) simultaneously. This is only possible with a multifocus device. It moves the objective electronically (in micron steps) closer to the sample and takes images at every step (height section). The images are then electronically overlapped into one image and thus result in an extreme depth of field (see also → image resolution, → field glass principle, → Greenough principle, → macroscope, → microscope, → stereomicroscope, → depth of field, and → topography).

Multifocus recordings

→ Stereomicroscope

MVR analysis (MVR value)

The flow behavior and the thermal and mechanical degradation of plastics is examined with MVR analysis (melt volume flow rate). The macromolecule length and strength decreases with increasing MVR, as for the → MFR value.

Nanocomposites

Nanocomposites are plastics with nanoparticles (see also → nanofillers).

Nanofillers

Nanofillers (e.g., montmorillonite, a clay constituent) are additives with grain sizes in the nanometer range of 1 to 100. They improve the barrier properties, fire resistance, strength, hardness, transparency, and toughness in the nanocomposites (molded parts with nanoparticles) (see also → nanocomposites).

Needle shut-off nozzle

A needle shut-off nozzle prevents an unintentional leakage of already plasticized molding compound during the plasticizing at the tip of the injection unit. The needle shut-off nozzle only opens when the injection pressure is established (see also → impression, (molded part impression), → cold plug, → plasticization unit, → plasticizing, and → over-injection).

Neofluar lenses

The term means that the objective contains fluoride glasses (see also → achromatic lens and → plan apochromatic objective).

Normal stress center A normal stress center (normal stress zone) is a circular fracture center with perpendicular fibrils. A stressed cross-section always fails first at a flaw (foreign particles) with a circular fracture point (failure center) and perpendicular fibrils or multiple fractures (see also → fracture center, → fibrils, → and foreign particles). Notch effect

A notch effect is caused by stress concentrations in nonrounded transitions, striae, or scratches, which often lead to cracking (see also → design error).

Notch(es)

A notch is a very deep groove, and a groove is deeper and wider than a scratch. The order, sorted by depth and width, is scratch, groove, and notch (see also → notch effect, → scratch, → surface error, and → groove).

Novice terms

See page 76

Nucleating agents

A nucleating agent is an additive in the molding compound, added to achieve an improved (continuous) formation of spherulites. Nucleating agents are typically added to thick-walled molded parts (e.g., thickwalled extrusion plates) so that the spherulites arise in the entire cross-section, not only in the plastic core. However, sometimes an atypical spherulite structure can develop in the molded part with large spherulites in a small spherulitic matrix. Pigments also act as nucleating agents (→ additives, → semifinished parts, → spherulites, and → spherulite formation).

Numerical aperture

→ Aperture, numerical

Object micrometer

→ Ocular

Object slides

→ Fig. 103 (see also → thin section, → glass slide)

115

Definitions

Technical Terms

Definitions


Objective

Technical Terms


Objective

In a microscope consisting of a two-stage lens system, the first stage is the objective and the second stage the ocular. The objective determines mainly the magnification and resolution (aperture) and the ocular the final magnification. The number of absorbed photons (dots) and hence the resolution increase with increasing aperture (see also → aperture, → resolution, microscopic, → microscope, → ocular, and → magnification).

Objective revolver

→ Universal microscope

Ocular

A reticle (measuring plate) is usually installed in an ocular. It is, along with the sample image, made visible in the ocular pupil that also corresponds to the eye pupil. The “black image border” of the microscope image develops at the border of the visual field. The lenses in the eyepiece bundle the light onto the retina, and dioptric correction occurs in defective vision with the focus ring. To measure the length of for example glass fibers, graduation marks for each objective, which can be read off the reticle for each objective and each magnification with an external measuring stage (stage micrometer), are calibrated and the reference values are listed in a table (see also → dioptric compensation, → defective vision, and → fiber length determination).

ODSC analysis

ODSC analysis (oscillating DSC analysis) is used, for example, for measuring the degree of gelling and the crosslinking of plastics. The recorded curve is composed of a Cp component (heat flow reversible processes) and kinetic components (heat flow irreversible processes). Reversible processes are glass transition and melting. Irreversible processes are crosslinking, relaxation, evaporation, and gelation. An advantage is the high sensitivity at a high heating rate and, at an average rate of heating, the high temperature resolution. The kinetic component is used for the analysis to determine the degree of gelling (see also → DSC analysis).

OIT analysis (DIN 53765)

The oxidation induction time OIT is the elapsed time (stability time) up until a plastic sample is oxidized in oxygen at a defined temperature. The OIT analysis is measured by a DSC analysis device (see also → DSC analysis).

Operating temperature

Operating temperature is the temperature that is applied to a molded part during its intended use.

Optical path of the pupil

The optical path of the pupil consists of aperture diaphragm, lamp filament, objective pupil, and eye pupil. The aperture diaphragm controls the contrast in the optical path of the pupil (see also → aperture diaphragm and → hatch optical path).

Orange skin

Orange skin (orange peel) is formed when the molding compound of the mold surface is not perfectly wetted. This occurs at a too-low mold and/or molding compound temperature, a too-low or too-early dropped holding pressure, or a too-slow filling. In a, for example, cold mold, the molding compound marginal layers solidify prematurely and may therefore not be adjusted well enough to the mold surface. The same happens when the holding pressure creates no shrinkage compensation, the flow path is very long, or the injection speed is too slow. The term orange structure is also used when a structure similar to an orange skin is present or the cause is at first not known (see also → mold temperature and → cold flow).

Orange structure

→ Orange skin

Orientation

The orientation is the orientation of filler and reinforcing materials in a molded part. It would be important to have an orientation of the filler and reinforcing materials in the direction of stress, so that the forces acting in use can be optimally transferred without molded part fracture. For example, in a glass fiber reinforced molded part, filler and reinforcing agents are mostly diffusely distributed. Improvements are filling studies with a possible mold correction (see also → filling studies).

Orientation stresses Orientation stresses are caused by macromolecular orientations, shear orientations, orientations of filler and reinforcing agents, for example, at unequal temperature in the mold, and long-acting holding pressure (see also → internal stresses and → design error). Overheating, thermal

116

At a thermal overheating, a degradation of the molding compound usually occurs only in the region of the molded part surface. Thereby, brown or black streaks are formed from the burned molding compound. The cause is the destruction of the macromolecular chains by friction, high melt temperature, too-long dwell time in the plasticizing unit or in the hot runner, and unfavorable flow paths. Thermal decomposition begins with thermal overheating (see also → brown streaks, → diesel effect, → friction, → hot runner, → macromolecules, → plasticization unit, → plasticizing, → black streaks, → thermal damage, → dead corners, → dwell time, and → decomposition, thermal).

Painting error



Over-injection

The molded part weight increases with an over-injection. An over-injection is present when a mass protrudes through the molded part surface (mold surface), or molding compound particles, which adhere in the mold from the previous shot, are injected on the sequence shot, or if a too-high injection pressure or holding pressure overfills the mold. A shaped mold damage (dent, quirks) on the molded part surface simulates an over-injection. Likewise, it is the convex expansion over a blowhole in still warm molding compound due to a too early ejection (see also → impression, → injection pressure, → following shot, → weight change, → vacuoles and blowholes, → material residue transfer, → holding pressure, → holding pressure error, → particles, and → plastic deformation).

Oxidation

Oxidation leads to the destruction of the plastic matrix by an oxygen attack (still burning), such as the rusting of metal (see also → aging, → matrix, and → radiation protection).

Oxidation stability

→ OIT analysis by means of DSC analysis

Oxidation-induction time

→ OIT analysis by means of DSC analysis

Oxygen diffusion barrier

An oxygen diffusion barrier should prevent the penetration of oxygen into pipes and containers. Oxygen diffusion barriers include AL-sheathing for corrosion protection in heating pipes (see also → diffusion barrier).

Packaging and transport

Important influences on the molded part quality are: Packaging and packaging safety

Tightness against transport influences, labeling (such as: Caution fragile), cardboard, stability of package or wooden box, packaging paper, corrugated cardboard (e.g., discoloration)

Transport and transport influences

Land, air, or sea route, heat, cold, air pressure differences, humidity, media and their migrations, as well as salty sea air (corrosion)

Transport time

Hours, days, or weeks (e.g., shrinkage, warpage)

See also → aging, → dent, → molded part quality, → notch, → corrosion, → scratches, → painting error, → media influences, → quality influences during injection molding, → groove, → shrinkage, → discoloration, → discoloration, and → warpage. Paint embrittlement

→ Painting error and → embrittlement

Paint streaks

Causes of paint streaks are, for example, an aged paint, which is refreshed with thinners, which is perhaps even mixed insufficiently. Flow streaks on the molded part are then formed during spraying by differences in viscosity. Other reasons are pressure variations when applying the paint, a washed-nozzle diameter, a too-strong draft, or an unclean molded part surface (see also → painting error and → streaks).

Paintability

→ Wetting test, → adhesive tape test

Painting

Painting is undertaken to protect against light, UV and media effects, for visual enhancement, promotion, labeling, and for error concealment (see also → additives, → aging → age influences, and → painting error).

Painting error

Causes of painting errors are old paint residue (swirled), efflorescence, chemicals, nozzle (washed), nozzle spacing (to the molded part surface), mold release agents (residue), moisture, flame retardant, cavity temperatures (different), molded part shrinkage, foreign particles (in the molded part surface), glass fibers (visible), hands (dirty), hardener quality (old, moist, dense vessels are used), circuit with dirt accumulation, paint application after pot life has been exceeded, paint batch changes, paint hardening speed, paint system (aged), paint restrainer (inhibitor), drafts (strong), molding compound flows (unequal), surface roughness, PE admixture (instead of H2O conditioning), quality of the cleaning bath, cleaning agent (mixed up/forgotten/dirty), spraying pressure fluctuations, spray fog distribution (bad), temperatures (high), transport factors (land, air, or sea), drying temperature, contamination during handling, processing parameters (changed temperatures, times, pressures), injuries (mechanical), packaging materials (wrong), mold slider grease, and, in silk screening, cleanliness of the cloth and cleaning frequency. If a paint error always occurs at the same place, a systematic processing error is often present (see also → fading, → efflorescence, → solvent evaporation, → wettability, → wetting test, → masterbatch change, → delamination, → demolding agents, → color change, → error, systematic, → foreign particles, → electroplating error, → thread overload, → adhesive tape method, → paint streaks, → paint embrittlement, → mass flows, → surface error, → surface roughness, → surface discoloration, → preparation agent, → cleaning agent influence, → residue, → damages, mechanical, and → packaging and transport).

117

Definitions

Technical Terms

Definitions


Particle

Technical Terms


Particle

Particles are unintentional impurities: foreign material (foreign particles, foreign granulate) or unmelted granulate. Metal particles (gray gloss particles) are caused by abrasion in the plasticizing unit. Cold particles (e.g., cold plug), which are often sharp-edged, cooled particles, are entrained from the nozzle area or runner. They are usually located close to the sprue in the molded part surface, partly with a film-like edge. Causes for cold particles are nozzle temperature and melt temperature that is too low, an injection speed that is too high, and poor homogenization. Particles can come from a filling system, a molding compound change, or contaminated residual granulate additive (see also → injection rate, → foreign granulate, → foreign material, → foreign particles, → granules, unmelted, → homogenization, → cold particles, → cold plug, → mass temperature, → metal particles, and → plasticization unit).

Parting plane

The obsolete term is now called mold separation, because the mold surfaces, which open during ejecting, are not always in a plane (see also → mold separation).

Perforated disc

The perforated disc is a round metal plate with many holes in the extruder head. It usually creates the back pressure that is required for homogenization with an additional screen pack during → extrusion.

Perforated disc imprinting

→ Perforated disc, → strainer impression, and → screen pack

Phase contrast AL-PH and DL-PH

With the phase contrast AL-PH, filler and reinforcing materials of elastomers and rubbers are examined, such as asbestos fibers, glass fibers, mica, kaolin, siliceous chalk, silicic acid, talc, and ethylene propylene tar copolymer EPDM. The phase contrast DL-PH was almost never needed for plastic examinations (see also → contrast processes in microscopy).

Phase displacement

A phase displacement is a path change. It occurs at the passage of light through a Wollaston prism (see also → phase contrast and → Wollaston prism).


A pigment conglomerate is formed in the molding compound to be colored through an accumulation of color pigments in a poor homogenization and intolerance of the masterbatch carrier or of the color pigments. Good homogenization is impossible in an incompatibility between the masterbatch carrier and the molding compound (see also → dispersion, → foreign granulate, → homogenization, → masterbatch carrier, unsuitable, → pigment streaks, → regranulate, → residual granulate, and → streaks).

Pigment conglomerate over 80 µm

→ Masterbatch carrier, → dispersion.

Pigment determination

Pigment types are determined with thin layer chromatography. The solution rises up an aluminum oxide or silica gel coating on a glass plate after dissolution of a plastic sample in a solvent. The climbing height is a characteristic for determining the pigment type.

Pigment streaks

Pigment streaks result from a poor homogenization of pigments that are difficult to disperse, unsuitable masterbatch carrier, residual granulate, subsequent coloring with masterbatch or liquid color, or when the rotation speed, homogenization, jacket heating temperature, screw geometry, or the L : D ratio is too low. In polarized light, dark streaks are easily overlooked in the black image background in a 10-micron thin section. Therefore it is important to examine without polarizing filter or with a brightening -plate. These produce a red-violet image background. Pigment streaks appear divisive and fundamentally disrupt the intermolecular bonding forces. A sieve or perforated disc imprinting causes concentric pigment streaks in the semifinished part (pipe) during extrusion. They decrease the strength with increasing visibility (see also → perforated disc imprinting, → masterbatch change, → pigment conglomerate, → pigment streaks, concentric, → streaks, → strainer impression, and → stagnation pressure).

Pigment streaks, concentric

→ Perforated disc imprinting, → pigment streaks, → strainer impression

Pigments

→ Metal analysis

Pinking

Pinking is a pink coloration that occurs in PVC window profiles mostly on the east and north side due to nitric oxide reacting with phenolic antioxidants or titanium dioxide pigments, TiO2 (anatase). Remedy occurs through 0.2 to 1% zinc stearate additive. With the gray test, pinking (surface staining) can be detected early. In 1992 white PVC window profiles in England had a pink discoloration on the north and east sides (but not on the sunny south and west sides). This also happened in gutters, downpipes, fences, and other building profiles. In Germany, only a few cases have been reported. In all cases of damage, different production batches were built in, and in identical weathering various PVC window profiles discolor while others do not. At a colorimetric examination of the pink coloration with the CIELAB system,

Source: Reith, W., Kürzinger, A., Kunststoffe 85 (1995) 12, p. 2056

118

Plastic materials, amorphous


Technical Terms


Pinking

in particular Db* (yellow) and ∆*L (brightness) changed, but D*a (red) changed only slightly. This is mainly true for lead-stabilized profiles. Lead-barium-cadmium-stabilized profiles only rarely discolor with low cadmium content. Surface examinations with the scanning electron microscope, SEM, and with electron spectroscopy, chemical analysis, and artificial weathering in xenon testers were not significantly different. Only IR analysis showed increased hydroxyl groups. Amazingly, the pink coloration disappeared after a short period of time in dry exposure (see also → weathering, artificial, → pinking, → IR analysis, → surface discoloration, and → scanning electron microscope).

(continued)

For a quick statement as to whether freshly produced PVC window profiles will turn pink (pinking) during application, they are exposed in a sun tester under water. The profiles will then become gray after 24 h. The gray color indicates that subsequent pink coloration (pinking) will occur in use. The type of commercial lead stabilizer does not affect the gray coloration. Titanium dioxide pigments of a pigment type may receive intense pink coloration if they come from different batches. Pinking was only observed for windows on the north side (see also → pinking and → surface discoloration).

Pipe extrusion

→ Extrusion

Plan apochromatic objective

A plan apochromatic objective is corrected to the three colors red, green, and blue, so that all three colors can be seen in the focal plane without distortion (see also → achromatic lens and → Neofluar lenses).

Plastic behavior, understanding

A quality or damage claim should always be examined from the perspective of the plastic as well as its flowability up into the cavity end. The main influencing factors are temperature, pressure, time, and media as well as internal and external forces (see also → microscopic examination and → processing parameters).

Plastic burr

→ Web

Plastic core

The plastic core is the last region to solidify in the injection mold, located in the middle of the molded part wall. Because plastics are bad heat conductors, the temperature in the middle of the wall is the highest and acts there the longest. Therefore, the largest spherulites grow in this region of semicrystalline plastics (see also → spherulites).

Plastic deformation

A plastic deformation is a permanent change (deformation) of the original molded part shape. It is a generic term for many error influences through forces and stresses (all kinds), temperatures, and media, particularly in long-term exposure. Plastic deformations are or result from cooling speed in the mold and on the outside, cooling stresses, aging (surface degradation due to UV attack and the media), external forces, demolding errors (molded part), tough demolding, gaping cracks, mechanical damage, post-crystallization, shrinkage, mold overfilling, over-injection, and warpage (see also → aging, → deformation, → deformation layer, → demolding error, → post-crystallization, → shrinkage, → relaxation, → topography, → over-injection, → damages, mechanical, and → warpage).

Plastic embrittlement

→ Embrittlement

Plastic materials (see also table in the appendix)

Thermoplastics have an amorphous or semicrystalline structure; elastomers have a weakly crosslinked and thermosets a highly crosslinked structure. Rubbers are one of the elastomers, and thermoplastic elastomers are physically crosslinked. Polymer blends are formed by a chemical bond or mechanical mixing of two (or more) polymers. Nanocomposites are plastics with nano-sized fillers, and WPC plastics contain wood fibers. The properties of the types of plastics can be improved by filler or reinforcing materials. Determining the types of plastics and plastic qualities is done by plastic analyses (see also → glass transition temperature range, → main valence forces, → hot-cold mixture, → inversion layers, → crystallites, → crystallite melting temperature range, → analysis of plastic materials, → plastic materials, amorphous, → plastics, semicrystalline, → plastics, crosslinked, → macromolecule, → matrix (molding compound), → post-crystallization, → shrinkage, → nanocomposites, → nanofillers, → secondary valence forces, → polarization, → polymer blend, → polymerization, → marginal zone for amorphous plastics, → marginal zone for semicrystalline plastics, → marginal zone, poor in spherulites, → core, plastic, → spherulites, → spherulite streaks, → spherulite growth, → thermoplastic elastomers, → reinforcing materials, and → WPC plastics).

Plastic materials, amorphous

Amorphous plastics have disordered macromolecular chains and only one melting zone (DSC analysis). They are not colored, are often transparent, and are more brittle than semicrystalline plastics. Amorphous plastics include ABS, CA, PC, PETP, PMMA, PVC, SAN, SB, and PS (see also → DSC analysis, → plastics, semicrystalline, and → plastic materials).

119

Definitions

Pinking test

Plastic materials, crosslinked

Definitions


Technical Terms


Plastic materials, crosslinked

There are chemical and energetic crosslinking processes for processing crosslinked plastics that lead to new properties. Chemical crosslinking methods produce elastomers and thermosets, which are processed into semifinished parts and molded parts. Polyolefins for the production of drinking water and heating pipes are crosslinked with azo crosslinking, the angel process, silane crosslinking, and radiation crosslinking. Crosslinked plastics cannot be melted because their macromolecular chains are chemically crosslinked together (see also → thermosets, → elastomers, → semifinished parts, and → plastic materials).

Plastic materials, determine

→ Analysis of plastic materials

Plastic materials, semicrystalline

Semicrystalline plastics have spherulites. These are superstructures of amorphous and semicrystalline macromolecular chains. Therefore spherulites have two melting zones (DSC analysis). They are usually opaque and tough in contrast to amorphous polymers. Semicrystalline plastics include PA, PB, PE, PETP, POM, PP, and PTFE (see also → DSC analysis, → plastic materials, and → plastic materials, amorphous).

Plastic melt

Polymer melt is the name for a plasticized (melted) plastic, for example in the injection molding cylinder.

Plasticization unit (plastification unit)

In injection molding, the molding material is plasticized, homogenized, and injected into the plasticization unit. The plasticization unit consists of a cylinder with a screw, jacket heating, and a funnel. During extrusion it is the same, except that the molding material is not injected but continuously extracted (see also → injection pressure, → extrusion, → molding compound, → granulate, unmelted, → homogenization, → jacket heating, → screw, → injection molding, and → stagnation pressure).

Plasticizer migration → HPLC analysis (see also → migration) Plasticizing

Plasticizing is the mixing and melting process of plastic molding compounds for the production of molded parts, for example in injection molding units and in extruders (see also → injection molding, → extrusion, and → plasticizing).

Plasticizing errors

Plasticizing errors arise for example in a faulty jacket heating, a stagnation pressure that is too low, a homogenization time that is too short, and at an unsuitable screw (see also → injection molding, → extrusion, → plasticizing, and → plasticization unit).

Point analysis

With a point analysis, the finest residue on a molded part can be analyzed, including, after appropriate preparation, also residue in its interior. The point analysis is carried out, for example, with an FTIR spectrometer (infrared spectrophotometer) with connected microscope and MFR apparatus (see also → ESCA analysis, → FTIR analysis, → MFR analysis, → preparation, and → residue).

Polarization

→ Polarization contrast

Polarization contrast In particular semicrystalline plastics are examined with polarization contrast (AL and DL-POL POL), because (AL-POL and DL-POL) their spherulite structure is only visible when using a polarizing filter. The polarization contrast is also suitable for an examination of filler and reinforcing materials, elastomers, and rubbers such as kaolin, siliceous chalk, chalk, synthetic fibers, peroxides, sulfur, and talc. The polarization contrast becomes colored with a lambda plate. Further, material stresses and double refractive samples are examined (see also → double refraction, → filler materials and reinforcing materials, → contrast processes in microscopy, → plastic materials, → lambda plate, → polarization optics, → polarizer, → spherulites, and → reinforcing materials). Polarization optics

Polarization optics consist of a base plate with two large, perpendicularly rotating polarizing filters with variable spacing relative to each other. In between, the molded part to be examined for molecular orientation is illuminated with monochromatic light. But this is only possible in transparent to translucent molded parts. The light source is located in a box behind the rear polarizer. By crossing the polarizers, as in the microscope, the isochromatics are made visible. The polarizing filters are often made of multi-axial polyisobutylene films PIB* between two glass panes. Polarization optics are easily self-produced (see also → isochromatics). * PW64-polarizing films, Oberlandglas AG, www.oberlandglas.de.

Polarized light

120

Light is linearly polarized as it passes through a polarizer. Phase displacements  occur when passing through a double refractive sample (see also → polarizing filter). The phase displacement gives: /4 (or  3/4,  5/4 …)

circularly polarized light

/2 (or /0,  3/2 …)

linearly polarized light

/5 (or values between /4 and /2)

elliptically polarized light

Polymer blend



Polarizer (polarizing filter)

A polarizer (“optical lattice”) linearly polarizes the light. That is, from the confusion of the light polarization direction, oscillating light is transmitted only in the preferred plane (“lattice direction”) of the polarizer. At 90° crossing, the analyzer locks the preferred plane and lets “no” light through. The field of view is then black (as in amorphous thin sections). At the position of the analyzer (hence it is called so), the preferred plane of the polarizer can be analyzed. If the visual field is black, the analyzer is rotated 90° to the polarizer. Double refractive samples split and rotate, due to unequal refractive indices, the linearly polarized light that is coming from the polarizer into two sinusoidal, mutually perpendicular oscillating light bands with unequal intensity (brightness) and phase (path difference). These enter the analyzer, which passes all light bands that lie in its vibration level. Brought into this level, they remove or strengthen themselves in the intermediate image and shine brightly in the field of view on a black image background. Double refractive samples (letters appears twice when reading through) are, for example, apatite, calcite, kaolin, aluminum oxide, chalk, quartz, spherulites, starch, talc, zircon, and sugar. A double refraction is also produced, for example, by material stresses in PMMA, PS, PC, PETP, and CA (see also → double refraction, → contrast types, and → polarized light).

Polarizing filter

→ Analyzer, → contrast types, → polarizer, → universal microscope

Polished sample

A polished sample is created by polishing a block ground sample. This increases the contrast of the events and edge crossings become sharper. Polished samples provide, after a much shorter production time as compared to thin ground samples, an answer to the distribution and orientation of fillers in a sample (see also → filler materials and reinforcing materials, → polishing, → grinding, and → vacuoles and blowholes).

Polishing

Polishing is a machining process and follows grinding from a surface roughness of about 15 microns, usually with four polishing stages: 6, 3, 1, and 0.25 microns. A final polishing with 1 micron is mostly sufficient. This then gives a surface roughness of about 0.05 to 0.1 micron. Mainly diamond pastes and aluminum oxide (Al2O3) are used as powder or suspension. The much cheaper alumina cools better and can be used more generously. The removal is also faster and the temperature load of sample and polishing cloth is lower. The polishing grain is applied to a polishing cloth. The sample cooling is preferably done with water, since solvent-based coolants and lubricants may attack the plastic surface. It is removed and displaced through cutting and rolling of the polishing grains. An amorphous or semicrystalline deformation layer (Beilby layer) mixed with polishing grain can occur at a heavy polishing pressure. Or grooved edges are flattened, which simulates a good polish. A cleaning in an ultrasonic bath is performed after each polishing step to ensure that no polishing grains will enter the following, finer polishing stage, and a microscopic examination is done at 30-fold magnification for relief, scratches, and flatness. In plastics without reinforcing materials, immediately after grinding with the graining of 180, 220, 320, 500, 800, 1200 and 4000, a quick polish with 1 micron alumina suspension on a soft buffing wheel is possible (see also → deformation layer, → type of plastic material, → polishing agent → polishing cloth, → surface roughness, → grinding, and → topography).

Polishing agent

Diamond powder, paste, or spray, aluminum oxide (Al2O3) as a powder, and aluminum oxide suspension (Al2O3 in H2O) are used for polishing. Aluminum oxide is much cheaper than diamond and can therefore be used more generously. This means a quick removal, good cooling, and low temperature load of sample and polishing cloth (see also → polishing).

Polishing cloths

Cleaning with polishing cloths is most easily done under running water with a soft hand brush. After drying, diamond spray is sprayed onto the rotating polishing disc for about 2 seconds or 0.3 g diamond paste is circularly applied. That’s enough for about 20 minutes of polishing. Soft polishing cloths create few scratches but a rough relief (topography) through a stronger erosion of the soft phases of a glass fiber reinforced sample. They are mainly used for final polishing of unfilled molding compounds. Hard/ rough polishing cloths create a finer relief (topography), but more scratches. They are mainly used for pre- or final polishing of unfilled molding compounds. Soft polishing cloths are used for nonreinforced and hard ones are used for reinforced samples. Medium-hard polishing cloths are compromises (see also → polishing).

Polymer blend

A polymer blend consists of two or more types of plastics. Polymer blends with new properties are created in the physical or chemical blending of types of plastics. A physical polymer blend is mostly made from two homogeneously mixed plastics and a chemical polymer blend by chemical bonding of plastics partners. Polymer blends are, for example, ABS/PC, MABS, PA/PE, and PS/PE (see also → plastic materials).

121

Definitions

Technical Terms

Definitions


Polymerization

Technical Terms


Polymerization

Polymerization, addition, and condensation are manufacturing processes for plastics. Monomers (molecules) are thereby polymerized to macromolecules under heat, pressure, and catalysts. A 100% polymerization is impossible, therefore plastics, especially when heated, can deliver residual monomers, which have an adverse effect on other plastics or people. Styrene residues can, for example, trigger cracking under stress in PMMA and are highly toxic (see also → plastic materials).

Post-crystallization

Post-crystallization is, after the removal from the mold, an ongoing or incipient crystallization with spherulite growth at ambient or operating temperatures. The colder the mold temperature was, the greater the crystallization and thus the molding stresses and warpage (see also → molded part stresses, → post-shrinkage, → warpage, and → mold temperature).

Post-shrinkage

Post-shrinkage results from the size and duration of the temperature effect after the production of amorphous and semicrystalline molded parts. In semicrystalline plastics, a post-crystallization can also overlay. Post-shrinkage also causes molded part stresses (see also → molded part stresses, → mass accumulation, → media attack, and → crystallization).

Powder coating

→ Surface refining

Pre- and posttreatment

A pre- or post-treatment may have an impact on the quality of molded parts (molded parts strength). Pre- and post-treatments are → flame treatment, → etching, → vapor deposition, → printing, → flocking, → pickling, → coating, → electrostatic pre-treatment, → demolding agents, → deburring, → electroplating, → laminating, → painting, → lasering, → polishing, → powder coating, → remove residue, → welding (of molded parts), → tempering, → predrying, → heat exposure (see also → surface errors, → preparation agent, → surface roughness, and → topography).

Predetermined fracture point

A predetermined fracture point is a deliberate cross-sectional weakening on a molded part for a fracture initiation at a defined location, for example through a notch, saw, or cutting damage.

Predrying

→ Moisture in the molding compound, → residual moisture, and → embrittlement

Preliminary examination

The visual and macroscopic preliminary examination gives the first indications of sample quality and of further examination steps. Therefore, the molded part or semifinished part is first examined for abnormalities in the delivery state with the eyes and then at 5- to 30-fold magnification under the macroscope. This results in further action and quotation. Samples are removed from conspicuous areas with suitable preparation equipment and preparation techniques. The main examination of the already known (from the preliminary examination) or other abnormalities follows after any necessary pretreatment with preparation agents. However, the preliminary examination is in many cases already enough. Such abnormalities include, for example, type of gate; gate position and gate design; the depth of the crack in a section; section size; artifacts; weld lines; blistering; delamination; sink marks; geometry influences; cold flow lines; cold particles (cold plug); air pockets; matte and glossy areas; mechanical damage; pigment streaks and colors (regranulate); cracks; silver, gray, brown, air, and moisture streaks; specks; strand formation and clouding; and warpage (see also → molded part defects, → semifinished parts, → main examination, → macroscope, → microscopic examination, → multifocus, → preparation devices, → preparation agents, → preparation techniques, → universal microscope, and → examination, visual).

Preparation agent

Preparation agents are etching agents, diamond spray (polishing agent), embedding masses (EP, UP), fuchsine (coloring agent), epoxy resin (embedding agents), Eukitt (for thin section placement), fuchsine (red coloring agent), hot air, Canada balsam (for thin section placement), tape (single- and double-sided) and adhesive (for thin polishing and thin section samples), coolants (for grinding and polishing), solvents, wetting agents (make stresses visible), polishing pastes, cleaning agents (alcohol, leather, and paper towels), sandpaper (wet strength), abrasive pastes, abrasive powder, nitrogen N2 (for breaking elastomers), aluminum oxide spray (polish), unsaturated polyester resin UP (embedding agent), and Victoria blue (blue coloring agent). See also → cover glass, → thin grinding device, → thin section device, → freezing in liquid nitrogen, → fuchsine, → glass slide, → hot air treatment, → Canada balsam, → adhesive bonding, → solvent, → microscopic examination, → polishing, → Victoria blue, and Fig. 103.

Preparation devices

122

Preparation devices are cover glass, plunger (for cover glass), thin section machine (microtome), mounting press, file, marker pen (red, water-resistant), casting molds (PE, PTFE), heat gun, hot stage, Canada balsam or Eukitt, measuring cups, knives, measuring spoons, tweezers, polishing machine, dissecting needle, saws (band, hand, circle, hole, or jigsaw), scissors, melt table, vise, scalpel blades, syringe, sputtering apparatus, disc sander, thermal vessel (for liquid nitrogen N2), drying weights (for cover glass), ultrasonic cleaning equipment, hot air oven, vacuum bell, vacuum chamber, and hot gas welding equipment.

Quality influences during extrusion


Technical Terms


Preparation devices

See also Fig. 103, → thin grinding device, → thin section device, → embedding, → hot air treatment with hot air gun (make weld line visible), → microscopic examination, → polishing, → dissecting needle, → grinding, → scalpel cut, → clamping block method, → tempering, and → warm exposure.

(continued)

Preparation techniques are flame treatment (stresses, shrinkage made visible), etching (e.g., chromic acid etching, xylene etching), dissolving (component identification), wetting (check the wettability, crack initiation), fracture (under normal and low temperature), thin grinding, thin section cutting (and block section cutting), embedding (cold and hot embedding), coloring (red and blue), freezing in liquid nitrogen, hot air treatment (weld lines, stresses made visible), adhesive bonding (sample bonding), adhesive tape test (adhesion test), surface oxidation (wettability and adhesion), polishing (block ground samples, polished samples), sawing (hand, circular, jig, hole, or band saws), scraping (separation removal), grinding (split ground sample, block ground sample, thin ground sample), cutting (scalpel section, block section), and sputtering (gold plating) of SEM samples or for contrast increase of samples in the light microscope (see also → flame treatment, → section, → etching, → wettability, → block section, → thin ground sample, → thin section, → embedding, → coloring, → freezing in liquid nitrogen, → hot air treatment, → adhesive tape test, → contrast processes, → microscopic examination, → polishing, → polished sample, → sample preparation, → scraping, → grinding, → scalpel cut, → sputtering, and → gold plating).

Pretreatment

→ Pre- and post-treatment

Primary colored molding compound

→ Molding compound, primary colored

Primary forming

Primary shaping and forming are processes in manufacturing processes. During primary shaping, the molding compound is heated to the plastic range and melted. During forming, the molding compound is only heated until it reaches the thermoelastic or rubber-elastic region. Primary forming processes are for example injection molding and extrusion. Vacuum forming and bending are forming processes.

Priming

In primers, the wettability of a plastic surface is increased through spraying or brushing on a primer (paint-like liquid) (see also → wettability).

Printing

The most important methods for printing on plastics are, for example, screen printing, gravure printing, and tampo printing (see → surface refining).

Processing parameters

Processing parameters are the necessary temperatures, times, and pressures for processing plastic molding compounds to molded parts. They have a great impact on the quality of molded parts (see also → injection, → injection rate, → error, rheological, → molding compound temperature, → holding pressure, → quality influences during injection molding, → stagnation pressure, → temperature influence, → tempering, → processing, cold and good), → mold temperature, and → cycle time).

Processing, good and too cold

Cold processing means in the first sense that the molding compound temperature or mold temperature was too low. The processing is good when the present part quality meets all of the requirements and subsequent stresses. More influences to cold and good processing can be found under → quality influences during extrusion, → quality influences during injection molding, and → mold temperature.

Progress report


Protection against aging

See possibilities for protection against aging under → additives, → aging, → aging resistance, → aging influences, → causes of aging, → antioxidants, → vaporizing, → coating protects from light, UV, and media influence, → electroplating, → hydrolysis, → inhibitors, → painting, → light stabilizers, → radiation protection, → tempering, → heat stabilizers, and → heat exposure.

Quality

→ Influences on quality and costs

Quality error (molded part)

→ Quality influences during injection molding


The influencing parameters on the semifinished part quality during extrusion are → abrasion, → adhesive tape test, → aging resistance, → aging, → analysis of plastic materials, → blow molding, → brown/red coloring of PVC, → burn streaks, → causes of cracking, → cold flow, → cold flow error, → color change (molded part), → coloring, subsequent, → convection oven, → cooking test, → cooling time, → core, plastic, → costs, → counter-pressure, → crystallite melting temperature range, → crystallites, → curing, → dead corners, → deformation, → delamination, → design error, → dimensional errors, → discoloration, → dispersion, → drying time, → efflorescence, → embossing offset, → embrittlement, → error, human, → error, rheological, → error, systematic, → examination, comparing, → filler materials and reinforcing materials, → flow lines, → flow seam, → foreign granulate, → friction, → globule, → gloss measurement,

123

Definitions

Preparation techniques


Technical Terms



→ granulate inclusions, → granulate, unmelted, → groove, → haptics, → homogenization, → homogenization error, → homogenization, poor, → hot-cold mixture, → hot-cold streaks, → hydrolysis, → inversion layers, → jacket heating, → jam bushing, → level of gelling, → lubricants, → marginal zone in amorphous plastics, → marginal zone in semicrystalline plastics, → marginal zone, poor in spherulites, → mass temperature, → masterbatch, → masterbatch carrier, unsuitable, → masterbatch change, → matrix, → media, → media attack, → media cracks, → media influences, → media streaks, → metal abrasion, → moisture in the molding compound, → moisture streaks, → mold impression → molded part stresses, → molding compound, cold, → molding compound, flow behavior, → molding compound flow, reduced, → molding compound, reinforced, → molding compound temperature, → notch, → notch effect, → nucleating agents, → packaging and transport, → particle, → perforated disc, → perforated disc imprinting, → pigment conglomerate, → pigment streaks, → pinking, → plastic deformation, → plastic materials, → plasticization unit, → plasticizing, → plasticizing errors, → plastics, semicrystalline, → post-crystallization, → post-shrinkage, → pre- and post-treatment, → predrying, → processing, cold, → regranulate, → reinforcing materials, → relaxation, → residual granulate, → residue, → reversal of the flow front, → roughness, → scratches, → screen pack, → screw, → segregation, → semifinished part, → sink marks, → spherulite formation, → spherulite streaks, → spherulites, → molding compound residue transfer, → strainer impression, → streaks, → surface error, → surface quality, → surface refining, → surface roughness, → temperature influence, → tempering, → turbulence, → UV radiation, → UV stabilizers, → vacuoles and blowholes, → viscosity, → viscosity number, → volume shrinkage, → warm exposure → warpage, → weathering, artificial, → weight change, → weld line, → wettability, → wetting agent test (see also → influences on quality and cost and → quality influences during injection molding).

(continued)

Definitions


Quality influences during injection molding

124

The influencing parameters on the molded part quality during injection molding are abrasion, → adhesive tape test, → aging, → aging resistance, → analysis of plastic materials, → brown/red coloring of PVC, → burn streaks, → burr formation, → causes of cracking, → clamping block method, → cold flow, → cold flow error, → color change (molded part), → coloring, subsequent, → conditioning, → convection oven, → cooking test, → cooling time, → core, plastic, → costs, → crystallite melting temperature range, → crystallites, → curing, → cycle time, → dead corners, → deformation, → delamination, → demolding errors, → demolding onto conveyor belt, → design error, → dimensional errors, → discoloration, → dispersion, → drying time, → dwell time, → efflorescence, → ejector mark, → embossing offset, → embrittlement, → error influences, human, → error, rheological, → error, systematic, → examination, comparing, → filler materials, → filling study, → flow lines, → flow seam, → following shot, → foreign granulate, → fracture, → fracture center, → fracture types, → free-jet formation, → friction, → glass fiber, → glass fiber breakage, → glass transition temperature range, → globule, → gloss measurement, → granulate, unmelted, → groove, → haptics, → hold pressure, → holding pressure, → holding pressure error, → holding pressure time, → homogenization, → homogenization error, → homogenization, poor, → hot-cold mixture, → hot-cold streaks, → hot runner, → hydrolysis, → injection, → injection molding, → injection molding error, → injection pressure, → injection rate, → injection, turbulent, → inversion layer, → jacket heating, → lack of holding pressure, → level of gelling, → lubricants, → marginal zone in amorphous plastics, → marginal zone in semicrystalline plastics, → marginal zone, poor in spherulites, → mass temperature, → masterbatch, → masterbatch carrier, unsuitable, → masterbatch change, → matrix, → media, → media attack, → media cracks, → media influences, → media streaks, → metal abrasion, → moisture in the molding compound, → moisture streaks, → mold clamping, → mold closing force, → mold filling, → mold impression, → mold impression, poor, → mold temperature, → molded part seam, → molded part stresses, → molding compound, cold, → molding compound flow, reduced, → molding compound, flow behavior, → molding compound reinforced, → molding compound temperature, → notch, → notch effect, → nucleating agents, → over-injection, → packaging and transport, → particle, → pigment conglomerate, → pigment streaks, → plastic burr, → plastic materials, → plasticization unit, → plasticizing, → plasticizing errors, → plastics, semicrystalline, → post-crystallization, → post-shrinkage, → pre- and post-treatment, → predrying, → processing, cold, → regranulate, → reinforcing materials, → relaxation, → residual granulate, → residual mass cushion, → residue, → reversal of the flow front, → roughness, → scratches, → screw, → segregation, → sink marks, → spherulite formation, → spherulite streaks, → spherulites, → molding compound residue transfer, → stagnation pressure, → streaks, → surface error, → surface quality, → surface refining, → surface roughness, → temperature influence, → tempering, → turbulence, → UV radiation, → UV stabilizers, → vacuoles and blowholes, → viscosity, → viscosity influence, → viscosity number, → volume shrinkage, → warpage, → weathering, artificial, → webs, → weight change, → weld line, → wettability, and → wetting agent test (see also → influences on quality and cost, and → quality influences during extrusion).

Reinforcing materials


Technical Terms


Quality tests, comparing

→ Quality error, → examination, comparing, → processing, cold

Questions for the customer

During a customer request, on the telephone or written, it is very important to know the customer’s request as well as his/her suspicions or his/her knowledge in order to solve the problem. Clever questions often provide the first indications or suspicions and facilitate the report. Questions are: name, company name, address, phone number, accurate sample identification, molding compound, mold release agents, manufacturing, series, cavity, claim number, number of cavities, what is the damage assumption?, damage discovered by whom/where/when?, UV, media, and moisture influence, processing parameters, packaging, shipping, and transportation. Furthermore, the customer is very grateful for progress reports over the telephone. This deepens customer loyalty (see also → error, systematic, → moisture in the molding compound, → report preparation, fast and competent, → customer request, → customer contact, → processing parameters, → packaging and transport, → examination, comparing). Quickmarks are indications of failure and damage on plastic products.

Radiation crosslinking

→ Plastic materials, crosslinked

Radiation protection A radiation protection agent is an antioxidant (stabilizer) that protects against ionizing radiation (e.g., radioactivity) (see also → aging and → oxidation). Rayleigh criteria

→ Resolution, microscopic

Rebatching

→ Masterbatch change

Record grooves

→ Gate grooves, concentric

Red coloring, PVC

A red coloration in PVC window profiles is caused by improper, organic phosphates or antioxidants in a lead-barium-cadmium stabilization (Pb-Ba-Cd) of PVC window profiles. The addition of additives can suppress the red coloring (see also → additives and → surface discoloration and → blackening).

Redirecting the crack

Redirecting the crack occurs when a crack follows inhomogeneities, such as in pigment streaks, spherulite streaks, mass flows, and glass fiber orientations, or an existing crack from a brittle coating, film, or integral layer transfers into the adjacent layer. Amazingly, this is also possible when it is much harder (see also → glass fiber orientations, → painting error, → mass flows, → pigment streaks, → cracks, → spherulite streaks, and → embrittlement).

Refinement

→ Surface refining

Reflected light

→ Contrasting methods

Reflected light illumination

→ Fig. 106

Refractive index n

The refractive index n indicates how many times slower the light is in a medium compared to vacuum. Immersion oils have a refractive index of n = 1.51, such as glass (see also → resolution).

Regranulate

Regranulate is reground (granulated) molded parts, sprues, and runners. A regranulate additive of up to about 10% of the molding compound is common. It is noted that increasing regranulate content also decreases the molded part quality. In a regranulate additive, differently colored, bright or dark spots are often visible in the thin section (see also → runner, → homogenization, → residual granulate, → pigment conglomerate, → quality influences during extrusion, and → quality influences during injection molding).

Reinforcing materials

Reinforcing materials are glass fibers, glass flakes, nanofillers, as well as fibers made of aramid, boron, cellulose, carbon, linen, cornstarch, and PETP. They give molded parts a higher pressure, tensile, or bending strength. Aramid and carbon fibers are preferred for high-strength, lightweight structures (e.g., aircraft construction). Reinforcing materials made of glass increase mostly the weight and can also protrude into the molded part surface in cold processing. Glass pellets reduce the shrinkage of the molded part (see also → degradation, → nanofillers, → wear, → filler materials and reinforcing materials, → filler materials and reinforcing materials testing, and → cycle time).

n = VAir : VMedium

125

Definitions

Quickmarks


Relaxation


Relaxation

Relaxation is the reduction of macromolecule orientations by a tension decrease, for example during tempering. The macromolecular chains are thereby relaxing (moving against each other) through the influence of time and temperature. For example, a pressure-loaded plastic rod becomes shorter after some time, or a tensile-loaded one becomes longer. The new length is then continuously maintained, that is, the plastic rod relaxed. A plastic deformation is present in both cases (see also → macromolecules, → plastic deformation, → stresses, → tempering, and → processing parameters).

Release agent

Release agents are used to facilitate the molded part demolding from the mold. If they are not washed away, contrary to the manufacturer’s specification, → residue on the molded part surface (see also → efflorescence, → demolding agents, and → residue) develops.

Release agent residue

→ Release agent

Relief

→ Topography

Report (types)

Report is a generic term for company reports, court reports, inspection contract, inspection report, test report, and progress report. After the examination, the client receives a report with all of the results and description of the test methods used. If an examination is different from a standard or guideline, it has to be indicated, as well as any subcontract to third parties. All reports receive an order number on each side and a through-hole with the company logo to ensure data security and protect against forgery and two signatures at the end of the report. The job number is a serial number (of the previous contracts) with the year and day of order acceptance. It is created by the customer commitment, for example: 89420/2010. The order number is printed on each head page of the report (monitor number in test certificates).

Definitions

Technical Terms

Company reports A company report is a short report (such as a test report) with only one signature (time-saving like a letter or fax), without a prescribed structure. It contains a precise summary of the results in tables, assessments and conclusions about the damage, and indications for future damage prevention. Expert report A report has no defined structure. It can contain assessments or conclusions. A court report, however, has a fixed structure. It includes explanations of technical terms and should, at least in the abstract, be understandable for judges and lawyers (laypeople). It is therefore much more complex and extensive than a company report. Outline: 1.

Contract (wording of taking the evidence)

2.

Local inspection (Invitation, persons present, disclosure of the taken evidence, hints according to Code of Civil Procedure)

3.

Test material

4.

Test execution

5.

Test result

6.

Summary and conclusion

7.

Answering of the questions of the taken evidence

Test contract A test contract only includes the test result (without result evaluation) in an informal letter or fax and includes the order number for labeling. Test report The structure of a test report is described in ISO/IEC 17025:2000 under 5.10.3. It does not contain an assessment of results. If the customer wants an assessment, it is done separately from the test report, marked with the title “expert judgment.” Structure: Page 1: header with company logo; report number (order number); name, address, cover letter (date, character), and contract name of the customer; the order confirmation date; abbreviations from the secretary, clerk, and department; sampling and exposure of sample or testing period (from/until); number of text pages; test location with year-month-day; signed by department head and official in charge. Page 2 and following: 1. Contract, 2. Test material, 3. Experimental procedure, 4. Experimental result.

126

Report preparation, fast and competent


Technical Terms


Report (types)

Test certificate

(continued)

This test certificate is like a test report and may, however, contain an evaluation of results as well as comparisons with tolerances, or information to perform a specific standard or guideline. In the monitoring of products, the test certificate contains a contract number (e.g., 3646) as well as the current year (e.g., 2010), with a number for the half-year (e.g., 1 or 2) and the frequency (e.g., 3) in which the test is performed. The total contract number is then: 364610/1.3. Progress report A progress report contains the same order number as the subsequent final report and the information “Progress Report to Report No: 00000/year, Part 1.” This also applies to translations of reports. A written progress report or one over the phone provides customers with a quick assistance in decision-making under time pressure to remedy production errors and disputes. See also → evidence order, → report preparation, fast and competent, and → novice terms.


Customer contact, report structure, and time savings

Ask helpful questions of the customer and maintain neutrality Clever questions for the customer facilitate the examination. Protective claims as answers can be misleading. An appraiser must always be “uninfluenceable” and trust his/her own knowledge. Neutrality is difficult and should be taken seriously, because even a kindness and a pleasant appearance can be unnoticeably biased. However, attempted influence by threats, money, or gifts is easily recognizable (see also → questions for the customer). Customers are only interested in a quick, competent response Customers are only interested in a quick, competent response to their problems. Your problems do not interest them at all. You know: The day has 24 hours! Don’t let them see any feelings of being overloaded. A quick assessment, shortly after placing an order, or a written progress report impresses and generates customer loyalty and recommendation. Only the direct view in the microscope has full visual awareness and brings knowledge The entire field of view is not consciously detected. Only the well-defined, direct view (as in the 2° fovea area) is conscious and brings knowledge. Therefore, in microscopy, it is recommended that you scan the sample “point by point” with the eyes and observe any striking feature, even the slightest. A reflection on the possible cause and prevention facilitates searching for the technical term and comparison with the figures in the encyclopedia (see also → visual awareness region, microscopic, → defective vision, and → fovea). Quality and damage claims always examined from the perspective of the plastic Examine quality or damage claims always from the perspective of the plastic and its flowability up into the cavity end. The main factors are temperature, pressure, time, media, as well as internal and external forces. Attention to systematic errors should be paid Attention should be paid to whether a systematic error is present in the visual and microscopic preliminary examinations (→ error, systematic). Rheological error looks the same regardless of the plastic Damage errors, such as rheological errors, have the same appearance and the same causes in all semicrystalline plastics. This applies similarly to amorphous plastics. This knowledge is very valuable, especially when a wanted plastic is missing in the encyclopedia. Thus for example a weld line or cold flow line of a PA6 molded part looks just like the one of an ABS molded part (see also → cold flow and → error, rheological).

127

Definitions

The procedure of an expert opinion is divided into: customer request with a contract meeting to fine tune, offer with close examination description, order confirmation, progress report (in writing or by telephone), report release, and further discussions over the phone on outstanding customer questions. An examination is carried out after order confirmation from the customer. Caution should be taken: processing should not start with confirmation over the telephone! If jobs are at risk or if there is a high risk of loss, everything must stand back and the expert opinion has to begin immediately, if necessary with a lot of overtime (→ gain of time in expert opinions).


Technical Terms



Recognize differences between good and defective parts

(continued)


Differences that are relevant to the damage are quickly identified during a comparative examination between good and defective parts. Caution: a so-called good part can also be an untested retained sample pattern (defective part) (see also → retained sample, → damage reenactment, and → examination, comparing). Recognize differences between blowholes and vacuoles The difference between unwanted hollow spots, blowholes or vacuoles, allows a faster damage assessment. Both have a weakening effect in the cross-section. Vacuoles are caused by shrinkage and blowholes by outgassing or entrained air (see also → shrinkage and → vacuoles and blowholes). Immediately take pictures and describe striking features If several expert opinions are simultaneously processed, all striking features are immediately photographed and described in the microscopic examination, so that no considerations get lost or confusion occurs when writing the expert opinion (see also → striking features).

Definitions

Subcontract early enough After the microscopic examination, an immediate decision has to be made if subcontracts are to be assigned and to schedule them with relevant people. Time savings with difficult customers If the customers have a lot of work, they often want to quickly hand over damage samples for immediate advice. A commitment should be made. As an expert, you can quickly identify the cause of damage in the microscope and you can take some electronic images with explanatory texts. The most satisfied customer will then receive this first preliminary damage assessment. The report, with any further findings, follows two weeks later. With a high work load, you can also gain time with a phone call, through an immediate consultation by skilled → questions for the customer. Occasionally, a vocal customer wants to push through a forgotten order just before the holidays. And you will recognize on the phone that this order was on his desk for weeks. You will then reply: “It is unfortunately impossible for the present order quantity. Examinations are carried out within the order in which they are placed.”–and after a short pause–“I do not want to lose you as a customer and I want to suggest the following: Within three days of order placement and receipt of the sample you will receive a first damage assessment. Then your people can begin to take steps to avoid damage.” You can also say: “You will receive, as requested, an expert opinion. However, if you want a good one, I recommend investing more time. If necessary, we can then clarify all microscopic abnormalities with further examinations.” Usually, the customer accepts the proposal. With stubbornness you will require a 80% urgency and handling charge. If he accepts, it probably proves the importance of the sudden rush. You will immediately have overtime (this also pleases the boss), examine the damage samples, and take pictures of the abnormal samples. Then you will immediately send him/her the images with explanatory text by e-mail. This inspires him or her. After this gain of time, the expert opinion follows much later (see also → report and microscopic examination). Residual granulate

→ Granulate, unmelted

Residual mass cushion

See under:→ holding pressure, → lack of holding pressure, → microvacuoles, → vacuoles and blowholes

Residual moisture (Aqua-Track method DIN 53715)

The residual moisture is the water content that is still present in a plastic molding compound. Before processing, the majority of plastics have to be predried. At too-high residual moisture, streaks are generated on the surface of the molded part or the plastic embrittles through hydrolysis. The degree of drying, which is measured by gravimetric methods (e.g., aqua track method) measures the residual moisture in percent after predrying of a molding compound. The degree of drying is an important characteristic for good plastic processing (see also → hydrolysis, → streaks, → embrittlement, and → predrying).

Residual monomers

→ Polymerization

128

Room temperature fracture



Residue

A residue is a deposit on the molded part surface of liquid, oil, release agents, plasticizers, or dirt. In molded parts that are hard to demold, silicone and PTFE-free release agent is often sprayed into the mold, which supposedly does not have to be washed off. However, chemicals such as solvents (or their accumulation in the wash tank) that are included in the release agent can diffuse into the plastic surface and can diffuse back out through the paint layer as efflorescence or residue (see also → efflorescence and → pre- and post-treatment).

Residues

→ Painting error, → packaging and transport, → efflorescence

Resistance to aging

The aging resistance (lifetime) is the resistance of molded parts to aging. An accelerated aging of samples is, for example, reached after 24 hours at 90 °C in a convection oven with and without chemicals, and also by weathering or heat exposure, a cooking test, or an exposure test (see also → aging, → weathering, → exposure test, → cooking test, → media, → media attack, → media influences, → media cracks, → media streaks, → wetting test, → convection oven, → impact assessment, and → heat exposure).

Resistance to chemicals

Before an application, molded parts made from plastic should be deposited into the chemicals (determine temperature and time empirically or from data sheets) against which they later have to be resistant through exposure tests (see also → etching, → media attack, and → impact assessment).

Resolution, microscopic

The resolution increases with the refractive index n, the numerical aperture NA of the objective and condenser, decreasing wavelength λ of lighting, cleanliness, and proper cover glass thickness, and it decreases with decreasing aperture diaphragm. After the “Rayleigh criterion,” 20% brightness distance would be enough for detail distinction in modern microscopes; however, even 10% would be satisfactory. = d0

1.22  1.22  = NAOb + NAKo 2 NA

NAOb = numerical objective aperture = n sin a NAKo = numerical condenser aperture l = wavelength of the light [nm] d0 = resolution [nm], should be as small as possible Without contrast, there is no resolution. The greater the contrast and resolution are, the better the image sharpness. The contrast increases with the luminance and color difference of the sample details and therefore the detail discernment (resolution). The resolution is the still-recognizable detail distance d0 and the contrast and the needed brightness and color difference. An optical microscope reaches 1.5 microns as the highest resolution with immersion optics of 40x/1.4 i (see also → aperture, → aperture, numerical, → aperture diaphragm, → image resolution, → refractive index n, → cover glass thickness, → condenser, → contrast, → contrast processes in microscopy, and → microscope). Retained samples

Retained samples are good parts from a production batch. They prove the quality on demand and serve as protection against damage claims. But beware, a so-called good part can also be an untested retained sample (bad part) (see also → questions for the customer and → examination, comparing).

Reticle

→ Ocular

Reversal of the flow front (mass inversion)

A reversal of the flow front (mass inversion) occurs when the molding compound reaches the end of the cavity during the injection in the head stream but meets flowing molding compound when turning around. In the mixing area, the flow, which cooled and is turning around, is bonding to the molding compound, which is following and which is still warm. The “seam strength” is better the lower the temperature difference of the “welded” molding compound flows (see also → delamination, → error, rheological, → mass inversion (with and without air induction), → hot-cold streaks, and → inversion layers).

Rheological error

→ Error, rheological

Ring light

→ Illumination

Room temperature fracture

A room temperature fracture is only suitable for hard and brittle samples. It takes place between two pliers or through a light hammer blow to the sample, which is clamped in the vise. This results in the fracture of a previously inserted cut or saw notch of the predetermined fracture point. This allows fractures to be produced at a specified location (see also → fracture, at room temperature and low temperature and → low temperature fracture).

129

Definitions

Technical Terms

Definitions


Rotational molding

Technical Terms


Rotational molding

In rotational molding, zero or small series and molded parts with complex shapes are often produced. Therefore, for example, the inner wall in a closed mold is wetted with plastisol (caprolactam PA) at 140 °C and tumbling rotation. At up to four times refilled subsets of plastisol, a four-layered wall thickness develops in a “wet-on-wet processing” (visible in the thin section). The finished molded part develops then after several minutes of cooling under water vapor (e.g., a tank, see also → blow molding of hollow objects and → blow molding).

Roughness

The surface of molded parts that are well molded has a roughness corresponding to the mold surface. A cold mold and/or a holding pressure dropped too early worsen the roughness. Then the demolded molded part can show an orange skin, despite a highly polished mold (see also → impression, → holding pressure, → orange skin, → polishing, → grinding, and → topography).

Runner

The runner distributes the molding compound, which is injected via the sprue bushing into the mold cavities (see also → sprue and → cavities).

Sample focusing

Sample focusing is performed under a universal microscope on the rotary knob for adjusting the sample focus (see also → universal microscope).

Sample preparation for LM samples

Sample preparation is done with preparation equipment, preparation agents, and preparation techniques. In a machining sample preparation, stresses develop, which become partially exposed when dividing a sample. Therefore, it is recommended to use whole samples for testing molded part stresses. The preparation is basically done in the damage area (discoloration, cracking, breaking, cold flow area, etc.), or as close as possible. In the microscopic examination, the entire sample (as supplied) is examined. If it is too large, sample specimens are usually manufactured by thin section, thin grinding, breaking, cutting, or sawing. When comparing the quality of different batches, the samples must be taken at the same location. The following are needed for the preparation: preparation devices, preparation agents, and machining preparation techniques. LM samples are samples to be tested in the light microscope (LM) (see also → fracture, → thin ground sample, → thin section, → molded part stresses, → microscopic examination, → wetting agent test, → polishing, → preparation devices, → preparation agents, → preparation techniques, → sample preparation, machining, → scraping, → cutting, → grinding, and → examination, visual).

Sample preparation for SEM samples

Sample preparation takes place in the damage area or as close as possible. When comparing quality of different batches, the samples are always removed in the same areas. The preparation techniques are the same as in the case of light microscopy. The most important are breaking, embedding, polishing, sawing, grinding, cutting, and sputtering. All plastic samples have to be gold plated (sputtering) before the examination so that the electrical charge from the electron bombardment is discharged to ground through the gold layer. Therefore, approximately 10 mm × 10 mm samples are bonded onto small aluminum discs (Cambridge blanks) with a colloidal silver adhesive. After 1 h, the solvent is volatilized and the colloidal silver cures. The samples are then sputtered for up to three times for 1 min at 20 mA and 0.06 mbar vacuum and with a cooling period of 3 min between each run. The resulting approximately 120 nm thick sputtered layer (gold layer) directs the electrical charges very well. Furthermore, a secondary electron number, which is generating an image through the stronger reflection, increases. Also, other nonoxidizing materials besides gold are used, for example coal and platinum as a sputtered layer. It is important to work with clean tweezers, needle, and gloves to avoid disturbing contaminations of the image (e.g., by hand grease or perspiration). SEM samples are samples that should be examined under scanning electron microscopy (see also → fracture, → embedding, → microscopic examination, → polishing, → preparation techniques, → sample preparation, machining, → scanning electron microscope, → sawing, → grinding, → cutting, and → sputtering).

Sample preparation, Machining refers to processes such as sawing, drilling, scraping, grinding, and polishing. When dividing a sample, stresses are released, and a machining sample preparation can also create tensions. Therefore, machining only whole and unprocessed samples should preferably be used for a wetting agent test (see also → molded part stresses, → wetting agent test, → polishing, → sample preparation, → scraping, and → grinding). Sample table

The sample table is used to absorb, hold, position, and focus the sample to be examined. They include the aperture diaphragm, the field lens, the condenser, and the polarizer (Figs. 104, 105, and 107, see also → microscope parts).

Sawing

With sawing, test specimens are cut out of large molded parts with a hand, circular, jig, hole, or band saw for sample preparation. Removal is often right on the damage site (see also → sample preparation).

130

Semifinished part quality during extrusion



Scalpel cut

The scalpel cut is often used when a fast statement is desired. For example, the layer thickness of coextruded multilayer films can thus be determined very quickly. Film thickness is easy to measure when the film is clamped between two plastic blocks (see also → clamping block method) and quickly cut with a scalpel (bias is pulling), so that the layer transitions cannot simulate cut grooves. The clamped residue is then measured under the microscope at a magnification of 100 (see also → cutting and → clamping block method).

Scanning electron microscopy (SEM microscope)

In the scanning electron microscope SEM, a resolution of about 0.005 microns is reached with an approximately 100-fold greater depth of field (at M = 1000) than in the light microscope. From a magnification limit of about 50,000-fold, higher magnifications are only possible through an electronic post-magnification. If the resolution achieves about 1.5 microns in the light microscope, the examination limit for plastics is about 1000-fold. If the resolution in the light microscope is insufficient, further examination of up to about 10,000-fold magnification follows in a scanning electron microscope. For example, examined are aging, fracture surfaces (with cracks and tears, creep, and microcracks), copolymer and polymer blends (after etching or fracture), glass fiber-matrix adhesion, sizing of filler and reinforcing materials, intercrystalline microstructure cracks, media load (ozone, UV attack), and surface wear (see also → aging, → artifact, → etching, → resolution, microscopic, → filler materials, → glass fiber length determination, → plastic materials, → light microscope LM, → matrix adhesion, → media attack, → media exposure, → media influences, → media cracks, → media streaks, → microcracks, → polymer blend, → cracks, and → reinforcing materials).

Scattered light

A light trap hides scattered light in DIC, FL, RF, and POL in some microscopes. In a transmitted light objective (M = 25), an obliquely held (into the beam path) polarizing filter acts as an antireflective cap (see also → contrast processes in microscopy).

Scrape the oxidation layer

Before bonding or heating element welding of pipes and fittings (PE, PP, and PVC), the oxide layer can be scraped for a good bonding.

Scraping

Scraping is surface removal with a scraper or scalpel to, for example, expose the plastic surface of a painted molded part or individual paint layers in multiple layer paints.

Scratches

A scratch is a line-like, low recess (permanent deformation) in the molded part surface without beaded edges due to a mechanical injury. Grooves are deeper and wider scratches. For example, optical and cosmetic high-gloss products (e.g., lenses, flasks) respond (scratch) particularly sensitively to packaging papers that are wood-like, dirty, or contaminated by ink and UV brighteners (see also → dent, → notch, → surface error, → polishing, → groove, → packaging and transport, and → damages, mechanical).

Screen pack

The screen pack is a combination of several metal screens in the extruder head, and generates, together with the perforated disc, the necessary counter-pressure for the homogenization in → extrusion.

Screw

In injection molding and extrusion for plasticizing and homogenizing, screws with different geometries are used, such as vented screws or core progressive screws (see also → extrusion, → plasticizing, → plasticization unit, and → injection molding).

Search examples with technical terms

For search examples of technical terms found in microscopy, see → Preface

Secondary valence forces

Secondary valence forces are intermolecular binding forces between the macromolecules. These are hydrogen bonds, dipole, dispersion, and induction forces. They physically hold the macromolecular chains together. With increasing temperature, the macromolecular chains are increasingly moving (Brownian molecular motion), becoming more mobile, and finally melting. A macromolecular chain is chemically built up by the much stronger main valence forces (see also → main valence forces).

Segregation

A segregation of the ingredients (e.g., glass fibers) and an overmixing in the area of flow shadows can occur through flow processes in the mold at a sudden change in direction of the molding compound, especially in web areas.

SEM microscope

SEM stands for scanning electron microscopy (see also → scanning electron microscopy).

Semifinished part

Semifinished parts are unfinished products (e.g., extruded films, profiles, pipes, and plates) that are further processed. Molded parts are finished products (e.g., injection molded cups, housing, chairs, and gears).

Semifinished part quality during extrusion

→ Semifinished part, → quality influences during extrusion, and → quality influences during injection molding

131

Definitions

Technical Terms

Definitions


Separation seam

Technical Terms


Separation seam

→ Mold separation

Service life

The life of semifinished parts, molded parts, and molds is called service life (see also → aging, → semifinished part, → temperature influence, and → changing temperature).

Shape stains and matte spots

Shape stains are finger-shaped, leaf-like stains, dull or shiny, often close to the sprue. They arise, for example, if the molded part is still stuck in the mold at a premature ejection, especially in places of higher temperature. Matte spots are velvet matte spots at the sprue, on edges and cracks in wall thickness by a swirling molding compound. Remedy: Increase and polish the gate, increase mold and/or molding compound temperature, change injection rate, and round up wall thickness variations (see also → sprue, → marginal zone in amorphous polymers, → marginal zone in semicrystalline plastics, → marginal zone, poor in spherulites, and → injection molding).

Shear zone

→ Shearing

Shearing

Shearing occurs during flowing of molding compounds at different speeds. Here shear zones with longdrawn structure occur (see also → injection molding).

Shot (during injection molding)

→ Following shot

Shot weight

The shot weight is the molding compound weight that is required for the filling of the cavities during injection into the mold (see also → injection, → following shot, → molding compound temperature, → weight change, → cavities, and → webs).

Shrinkage

Shrinkage is an unwanted volume contraction in semifinished parts and in molded parts during cooling and afterwards, through a post-shrinkage and post-crystallization. The molded part weight remains constant at shrinkage, even if the molded part dimensions decrease. Therefore, the density increases locally (and the molded part stresses). There is cooling shrinkage in the mold and a post-shrinkage in use through a post-crystallization. The more mass volume is present, the longer the core remains plastic and has more time for shrinkage. Therefore, in large cross-sections, the vacuoles are also usually larger. A strong shrinkage can lead to cracking and fracture. Shrinkage causes dimensional changes in molded parts and semifinished parts and rarely vacuoles. Causes are often a too-early demolding of a molded part, too little holding pressure, too-short holding time, and lower processing temperatures (see also → molded part stresses, → holding pressure time, → holding pressure error, → shrinking, → core, plastic, → tempering, → warpage, → vacuoles and blowholes).

Shrinkage compensation

→ Lack of holding pressure

Shrinkage stresses

→ Aging, → molded part stresses, and → shrinkage

Shrinking

Shrinking is intentional shrinkage by heating (e.g., hot air) in the longitudinal and/or transverse direction such as in shrink films and heat-shrinkable tubing (see also → shrinkage).

Shrinking on

Shrinking onto the warmer mold parts (e.g., cores) is observed especially in semicrystalline parts. In molded parts, which are difficult to demold, a deliberate shrinkage by a partial increase in temperature in the mold can improve the demoldability.

Sickle aperture

→ Halogen light source

Silane crosslinking


Silver streaks

Silver streaks are silvery line streaks. They are formed by a thermal load (see also → streaks).

Sink mark(s)

A sink mark is a sunken surface area (well, dent). Causes: see also → holding pressure error, → shrinkage, and → vacuoles and blowholes.

Slip-stick effect

With a slip-stick-slip effect, a partner slides and stops onto another (such as an eraser on a glass plate). Chatter marks can also occur, depending on the surface condition.

Slit die extrusion

Films, sheets, and plates (web plates) are produced on a slit-die extruder. The method is similar to that described under extrusion. The mold, the slot die extrusion, is much wider and equal in size to the produced films, sheets, or plates (see also → extrusion).

Solution, quick


132

Spherulite growth


Technical Terms


Solvent evaporation

Solvent evaporation occurs especially when heated, by released monomer components in the plastic (e.g., vinyl chloride from PVC), at a thermal decomposition or earlier diffused media (e.g., solvent, cleaning agents, see also → media, → monomers, and → decomposition, thermal).

Solvents for plastics By dissolving the polymer matrix in solvents, the filler and reinforcing materials are separated and microscopically analyzed (e.g.,, glass fiber length determination). Common solvents are: (from worksheets from the following companies: BASF, Bayer, Höchst)

Acetone, chloroform, dioxane

MF

Benzylamine at 160 °C, ammonia

PA

Sulfuric acid (96%)

PA

Formic acid, sulfuric acid (concentrated), dimethylformamide, m-cresol

PB

Decane, trichlorobenzene

PBT

Phenol + 1,2-dichlorobenzene

PC

Dichloromethane (p. A.)

PE

Decane, trichlorobenzene, decahydronaphthalene, stabilized with 0.5% N-phenyl2‑naphthylamine

PEEK

Store in acetone for 1 h

PETP

Phenol + 2,4,6-trichlorbenzol (100 : 72)

PMMA

Acetone, chloroform, ethyl acetate, toluene, tetrahydrofuran

POM

Benzyl alcohol, and dimethylformamide at elevated temperature, benzene

PP

Isoamyl acetate

PP

Decahydronaphthalene, stabilized with 0.5% N-phenyl-2-naphthylamine

PPE

Methanol with trichloroethylene 2 : 1

PS

Acetone, benzene, toluene, chloroform, carbon disulfide

PS

Toluene

PSU

Acetone, chloroform

PTFE

Insoluble

PUR

Formic acid, m-cresol, dimethylformamide

PVDF

Sodium hydroxide solution, dimethylformamide

PVF

Cyclohexane, dimethylformamide

SAN

Methyl ethyl ketone

SB

Toluene

UF

Benzylamine at 160 °C, ammonia

Definitions

CA

(See also → dissolving, → glass fiber length determination, → solvent, → media that can cause stress cracking, → media cracks, and → microscopic examination.) Speck

A speck is a highly molecular, hard to melt, or crosslinked film particle with an unfavorably wider distribution of macromolecule lengths. The cause of specks is their wider melting range (Gaussian) or often a foreign material in the film (see also → film blowing, → film manufacture, → foreign material, and → extrusion).

Spherulite deformation

See Figs. 55 and 57, → error, rheological.

Spherulite growth

→ Spherulites, → spherulite streaks

133

Definitions


Spherulite streaks

Technical Terms


Spherulite streaks

A spherulite streak is a molded part volume of large spherulites with sharp boundaries in a small-spherulitic matrix or vice versa. Spherulite streaks often produce a notch effect in the transition area from large to small spherulites (large-small spherulites). The notch effect can lead to fractures in use. There are three causes for spherulite streaks: 1.

Injecting a hot-cold mixture (with temperature streaks) due to a poor homogenization of noncolored molding compound in the injection cylinder.

2.

Injecting a subsequently unevenly colored molding compound, as a result of a poor homogenization in the injection cylinder. Large spherulites grow in the molded part areas with few pigments, because the pigments, which are acting as crystallization nuclei, have a lot of room to grow there.

3.

Injection that is too fast (oscillating mold filling) creates a mass swirling of the hot, plastic core with the cold marginal zone in the mold. The spherulites become the largest in the plastic core because the heat is at its highest and is acting longest.

See also → molding compound, primary colored, → large and small spherulites, → notch effect, → matrix, → marginal zones for semicrystalline plastics → core, plastic, and → spherulites. Spherulite(s)

A spherulite is a spherical, spatial superstructure of amorphous and semicrystalline regions. If the molding compound temperature in the mold falls below the crystalline melting temperature range, the spherulites start to spherically successively overgrow on crystallization nuclei (pigments, thermal nuclides, inhomogeneities, etc.). In case of contact, pressure areas develop on the spherulites. Spherulites need heat and time to grow. Therefore, they are the largest in the “plastic core” (wall center) and decrease in size at the cooler mold wall. If a high temperature is in effect for a long time, they become very large (giant spherulites). In the melt, usually all unpigmented, semicrystalline thermoplastics are transparent (amorphous). During cooling from the glass transition temperature, the spherulite growth starts on the crystallization nuclei (impurities, nucleating agents, and pigments). The plastic is thereby not transparent (see also → glass temperature, → hot-cold mixture, → hot-cold streaks, → plastics, semicrystalline, → nucleating agents, → marginal zone for semicrystalline plastics, → streaks, → core, plastic, and → spherulite streaks).

Split ground sample

Split grinding is used for sample preparation and also for reducing grinding time of a thin ground sample to quickly penetrate into a certain depth. The sample, which is embedded or directly adhered to the slide, is usually reduced to 0.5 to 1 mm thickness using a diamond blade, so that the resultant thin ground sample does not take too long to produce (see Fig. 109 and → thin ground sample).

Sprue

The sprue is a channel between the sprue bushing and the cavity. The molding compound flows through it when injecting into the closed mold. For more than one cavity, the molding compound passes from the sprue into the cavities through a runner. The runner should be dimensioned as large as possible and should also be polished to ensure that the molding compound can flow very well into all cavities. This is particularly important when cold flow lines or vacuoles are still present despite an increase in mold temperature. Then, an equal filling behavior (balance) should be attempted. In some cases, if structurally possible, a heating cartridge can help (see also → gate grooves, → runner, → section, → filling study, → cold flow lines, → cold flow →, cavity, → and mold temperature).

Sprue grooves, concentric

Concentric gate grooves are “record grooves.” They result from a reduced molding compound flow caused by a too-low molding compound and/or mold temperature (see also → gate, → cold flow lines).

Sputtering (gold plating)

Sputtering is the process of gold plating samples for examination under a light or electron microscope. The gold plating of samples is carried out to ensure static dissipation in the scanning electron microscope SEM or light microscope LM for contrast enhancement of transparent samples. Therefore these are bonded with colloidal silver onto an AL Cambridge blank and evacuated in a sputtering apparatus for 15 minutes. To remove residual gases, the sample chamber is then flushed with argon gas, a vacuum is once more created, and sputtering with gold proceeds at 0.04 Torr, 3 × 1 min long at 8 mA and 2.25 kV. Here, the sputtering is interrupted twice through a cooling period of 2 min, in order to avoid sample overheating (see also → sample preparation and → scanning electron microscope).

Sputtering layer (gold layer)

→ Scanning electron microscope

134

Stresses


Technical Terms


St. Andrew’s cross DBL 7384 and DBL 7399

St. Andrews cross with adhesive tape removal test according to DBL 7384, Sections 4.5 and 5.3 and DBL 7399, Section 5.1 (in amended form). According to this standard, a St. Andrews cross with less than 30° cutting angle is applied using a knife, and the test is carried out from the intersection (peeling paint on the scratch track ≤ 2 mm, max. 1 mm on each side). The cross-cut with adhesive tape removal should, for example, be no worse than Gt 1 to 2, scratch spacing 1.5 mm. Such a cross cut is only recommended on planar surfaces.

Stabilizer(s)

Stabilizers are → light stabilizers, → UV stabilizers, → heat stabilizers; see also → additives.

Stagnation pressure During injection molding, the stagnation pressure is the pressure on the rotating screw that is required for melting the molding compound (plasticizing). (see also → plasticization unit, → plasticizing, → screw, → injection molding, and → processing parameter) Stains include paint stains, grease stains, and acid stains (see also → efflorescence, → fracture, → demolding agents, → shape stains and matte spots, → electroplating error, → media, → media attack, → media streaks, → residue, and → overheating).

Steel needle

Fig. 103 (see also → thin section)

Stereomicroscope

A stereomicroscope has two separate beam paths, that is, two oculars for spatial, fatigue-free viewing. For quick switching, objectives of different magnifications are arranged on an objective revolver. Today, all microscopes should be true stereomicroscopes and have two oculars over one optical path (see also → microscope, and → examination devices, microscopic).

Strainer impression

In a thin section, a strainer impression is recognized as concentric pigment streaks through an impression of the screen packet in the extruder at poor homogenization. Concentric pigment streaks also develop through a perforated disc impression. In the extruder, the perforated disc and the screen pack are in combined use (see also → extrusion, → homogenization, poor, → perforated disc, → perforated disc impression, → pigment streaks, concentric, → streaks, and → screen pack).

Strand formation

Formation of strands occurs in the molded part surface or in its interior as a result of turbulent injection at too high injection pressure or with an inappropriate gating design (see also → section, → injection pressure, and → injection, turbulent).

Streaks

Streaks are strip-like areas in a molded part or on the molded part surface with a nonparallel, plan or spatial volume with an often different color density on the boundary line. There are → brown streaks, → moisture streaks, → flow streaks, → gray streaks, → warm cool streaks, → paint streaks, → media streaks, → pigment streaks, → pigment streaks, concentric, → silver streaks, → spherulite streaks, → streaks, thermal, → carbon black streaks, and → burn streaks.

Streaks, brown

Brown streaks develop through thermal overheating (see also → streaks, → diesel effect, and → overheating, thermal).

Streaks, thermal

Thermal streaks occur in a diesel effect and at a thermal overheating of the molding compound (see also → diesel effect, → streaks, and → overheating, thermal).

Stress center

→ Normal stress center

Stress crack corrosion

Stress crack corrosion occurs when corrosion interacts with inner and/or outer stresses. Then cracks occur that can lead to fractures. Corrosion always occurs first in the area of the highest molded part stresses through media influences. These are autocatalytic oxidation, hydrolysis, bases (surface corrosion), solvents, wetting agents (stress cracking and swelling), oils, ozone, and acid, and so on (see also → aging, → molded part stresses, → hydrolysis, → corrosion, → solvents, → media that can cause stress cracking, → wetting agents, and → oxidation).

Stress crack test (DIN EN ISO 4599)

The stress crack test or wetting agent test is used to determine the external molded part stresses. The larger the molded part stresses, the sooner stress cracks occur in a stress crack test. The stress crack formation is determined with the bent strip test according to DIN EN ISO 4599 (see → media that can cause stress cracking, → wetting agents, → wetting agent test, and → impact assessment).

Stress whitening

So-called stress whitening is a white-colored bending zone by many crazes. A stress whitening is not a fracture yet but indicates the beginning fracture zone by the white coloration (see also → fracture center and → craze(s)).

Stresses

→ Molded part stresses, → media that can cause stress cracking

135

Definitions

Stains


Stresses in the molded part

Technical Terms


Stresses in the molded part

Molded part stresses are unavoidable internal and external stresses in a molded part. They depend on the complexity of the design and are created by cooling with inhomogeneous density distribution (warpage), loading or overloading in use, a high injection pressure, crystallization, molecular orientation, high holding pressure (which is holding on for too long), post-crystallization, post-shrinkage, and volume shrinkage in mass accumulations (in the mold, when cooling and after). Furthermore, molded part stresses have an adverse impact on aging resistance and further processing, such as when printing, electroplating, adhesive bonding, and painting. Internal molded part stresses are stresses that are due to manufacturing and are unavoidable. They are created by internal forces but are also influenced by external forces. They are made visible with heat exposure in the range of the glass transition temperature.

Definitions

External molded part stresses are caused by external forces but also in connection with internal molded part stresses. They are made visible with a wetting agent test. See also → internal stresses, → foreign particles, → glass transition temperature, → hot air treatment, → air inclusion, → mass accumulation, → media attack, → MFR analysis, → holding pressure, → hold pressure, → holding pressure error, → post-shrinkage, → lack of holding pressure, → post-crystallization, → wetting agent test, → orientation, → pigment streaks, → relaxation, → tempering, and → heat exposure. Strips

Strips are elongated markings in or on the surface of the molded part surface with a largely parallel, flat and sharp borderline in inherent color or changing color. They arise between friction partners by their own abrasion or abrasion transfer from the friction partners (see also → streaks).

Structure study

A structure study refers to the construction and arrangement of macromolecules and all additives in a molding compound or in a molded part (see also → additives, → filler materials, → matrix, and → reinforcing materials).

Subcontraction

→ Report preparation, fast and competent and → microscopic examination

Sulfate ash content

→ Filler materials and reinforcing materials testing and → chalk in PVC-U. DIN EN ISO 3451-5.

Surface discoloration

PVC surfaces may have the following discolorations: a red or black coloration due to unsuitable stabilizers and antioxidants under the influence of temperature, moisture, and chemicals or thermal decomposition (see also → additives, → aging, → antioxidants, → fading, → efflorescence, → brown/red discoloration, → diesel effect, → fuchsine (coloring agent), → yellowing, → gray streaks, → pinking test, → media attack, → media influences, → surface errors, → pinking, → red coloring, → streaks, → blackening, → black streaks, → silver streaks, → stabilizers, → overheating, thermal, → ultraviolet radiation (UV radiation), → burn streaks, → discoloration, → Victoria blue (coloring agent), → stress whitening, and → decomposition, thermal).

Surface errors

Surface errors are caused by aging, evaporation errors, printing errors, flocking errors, coating errors, delamination, print errors, sink marks, color variations, stains, molded part errors, molded part stresses, foreign material, electroplating errors, application temperature, mass inversion (with and without air induction), glass fibers (reaching out), hydrolysis, cold flow, dents, scratches, conglomerates, design errors, painting errors, dull spots, media attack, holding pressure error, post-crystallization, stamping errors, roughness, cleaning agents, striae, delaminations, streaks, shrinkage, marginal zones that are poor in spherulites, power surges, damages (mechanical), predrying (poor), and warpage (see also → aging, → ejector mark, → delamination, → stains, → molded part error, → electroplating error, → mass inversion (with and without air induction), → glass fibers, → design error, → mass temperature, → matte spots, → hydrolysis, → groove, → notch, → scratches, → surface discoloration, → surface refining, → marginal zone in amorphous plastics, → marginal zone in semicrystalline plastics, → marginal zone, poor in spherulites, → cleaning agent influence, → predrying, → changing temperatures, → mold impression, → mold venting, and → mold temperature).

Surface refining

The objectives of a surface treatment are to improve haptic, improve transparency, increase temperature resistance, increase beautification (incentive to buy), and improve weather resistance. Methods for surface treatment include → vapor deposition, → printing, → flocking, → coating, → electroplating, → laminating, → painting, → polishing, → lasering (see also → surface errors, → surface discoloration, → roughness, and → topography).

Surface stress

→ Wetting test and → wetting agent test

Swan neck lighting

→ Illumination

136

Thermoset(s)


Technical Terms


Systematic errors

→ Error, systematic, → report preparation, fast and competent

Tear

Fig. 322, → fracture, → fracture types, and → fracture center

Temperature influence

The higher the temperature, the faster plastic ages. In particular, changing temperatures create rapid aging of plastics by expanding and shrinking parameters (see also → aging, → molded part stresses, → shrinkage, → tempering, and → changing temperatures).

Tensile stresses

→ Stresses in the molded part

Test certificate


Test pins, test ink

→ Wetting test

TG analysis

→ Thermogravimetry TG

Thermal damage

→ Overheating, thermal

Thermal streaks

Thermal streaks are hot-cold streaks. They are formed in an insufficiently mixed molding compound or through thermal heating during injection or extrusion. Such streaks are particularly well visible in transparent or translucent molded parts (see also → diesel effect, → hot-cold mixture, → homogenization, → streaks, and → overheating, thermal).

Thermogravimetry TG

The plastic components in polymer blends, as well as the filler and reinforcing materials (e.g., carbon black, carbon fiber content) in rubbers and polymers, are analyzed with thermogravimetry (TG analysis). In the analysis of plastic components, the mass loss of the sample in a gas atmosphere is measured by temperature rise. A precise balance is therefore necessary of a furnace with tempering, a gas supply for the gas atmosphere in the measuring room, and a measurement value recording. Purge gases are nitrogen, synthetic air, oxygen, or purge gas combinations (see also → analysis of plastic materials).

Thermomechanical analysis TMA

The thermomechanical analysis TMA determines the shrinkage-strain behavior and the coefficient of linear expansion of plastics (see also → DMA analysis and → analysis of plastic materials).

Thermoplastic elastomers TPE

Thermoplastic elastomers TPE behave like elastomers. They are physically crosslinked, extensible, always meltable plastics, which can be injection molded and extruded. At heating, the physically crosslinked macromolecule bonds dissolve, in contrast to the elastomer with chemical macromolecule bonds. An amorphous or semicrystalline thermoplastic can be mixed with an elastic rubber to form a polymer blend or it can be chemically bonded in a linear or radial structure (triple or quadruple chain) through block polymerization. Above the glass transition temperature, the physical crosslinks dissolve by melting of the amorphous or semicrystalline regions (see also → thermosets, → elastomer, → extrusion, → glass transition temperature, → plastic materials, → macromolecules, → polymer blend, → injection molding, and → thermoplastics).

Thermoplastics

Thermoplastics are amorphous or semicrystalline plastics, and they can always be plasticized (melted, e.g., ABS, PA, PC, POM, see also → plastic materials) even after molded part production.

Thermoset(s)

A thermoset is a plastic (e.g., EP, PF, SI, UP) that cannot be plasticized (melted) anymore after molded part manufacture. The former name of duroplastic was misleading because “duro” means hard, “plastic” means soft. A thermoset is a chemically highly crosslinked, hard plastic. The injection moldable and extrudable preproducts are only crosslinked in the processing through a heat treatment. Melting is then no longer possible.

137

Definitions

Stresses in plastics are reduced by tempering. This happens, for example, in a tempered exposure of Tempering (tempered exposure) molded parts after about 4 hours in a convection oven below or near the softening temperature. The stress reduction protects against cracking, possibly warping, and it also reduces media attack. Molded parts contain considerably more or less severe molded part stresses, particularly in cold processing with a major impact on the aging resistance and further processing (such as adhesion, painting). Location and size of the molded part stresses are often clearly visible after tempered exposure close to the glass temperature. The molded part, which is stored in a convection oven, is checked daily for warpage and the dimensions are measured. The frozen molded part stresses cause shrinkage (warpage) in the larger wall thickness in the direction of the sprue. The greater the molded part stresses, the greater the shrinkage (see also → aging, → sprue, → molded part stresses, → glass temperature, → painting error, → media attack, → shrinkage, → convection oven, → warpage, and → heat exposure).

Definitions



Technical Terms



Production of a thin ground sample is achieved using a thin grinding device (machine). The initial sample is fixed into a vacuum holder and ground in 5 to 10 micron increments. An embedding material is usually an epoxy resin, and for adhesion, a cyanoacrylate can be used (soluble in water!), but a diffusion adhesive based on acrylic is better. After reaching the final thickness of, for example, 20 microns, the diffusion adhesive can be carefully removed with a needle from the glass support after 10 minutes of immersion in ethanol. Most plastics are sufficiently resistant. Then the exposed thin ground sample is fixed to a glass slide with Canada balsam or Eukitt EK and is covered with a cover glass. In this way, clean thin ground samples without air bubbles, a separation point, and coolant back-migration can be created. Thin ground samples have a thickness of 5 to 50 microns and are used for microscopic examination of fillers and reinforcing materials. The event thickness determines the thin ground sample thickness. It is at least 20 microns thick in the case of samples with 10 micron thick glass fibers (event thickness), in order to at least preserve two crossing glass fibers. Thin ground samples of 20 to 50 microns are usually sufficient for orientation tests. The manual production of a thin ground sample is achieved using a disc sander with various wet abrasive papers with a graining of 180, 220, 320, 500, 800, 1200, and 4000. This method requires the least effort, but practice is required so that the sample is not tilted at an angle and ground on one side (see also → thin section device).

Thin ground sample

→ Thin grinding device

Thin layer chromatography

→ Pigment determination

Thin section

A thin section (Figs. 67 to 72) provides the fastest answer to the inner quality or structural damage of a molded part of all examination possibilities, in addition to providing instructions for processing, cause of damage, and remedy. Since an infrared spectroscopy IR or differential thermal analysis DSC only indicates the total crystallinity, the spherulites and thus the size and location of the crystallinity in the entire sample cross-section are visible in a thin section. Thin sections are created in minutes if the plastics can be cut and do not contain any abrasive (dulling) fillers or reinforcing materials (glass fibers, glass pellets, glass flakes, or minerals). Some samples cannot be cut because they are falling apart or soften (e.g., soft PVC, polyurethane rigid foams, elastomers, and isolated PMMA injection molding types). But PVC integral foams (KG pipes with PVC rigid foam between the inner and outer layer) are, for example, very easy to cut. To examine the polymer structure, the following equipment is required: a universal microscope, two dissecting needles (PVC, ∅ 5 × 200 mm long), a steel needle (15 cm), a compression die (16 × 16 mm), slides (76 × 26 mm), cover glasses (18 × 18 mm), Canada balsam, stainless steel tweezers (120 mm), a scalpel, and a leather cloth (Fig. 103). Thin sections are made with a thin section device (with a vertical cutting direction, Fig. 109) or with a sliding microtome (horizontal cutting direction). Procedure: The surface of a sample, which is clamped in a thin section device, is planned to have 30 micron air cuts, so that the subsequent thin section covers the entire sample length and width. Before the valid cut, there will be a preliminary cut in thin section thickness (10 microns are common), so the following cut will not be too thin. Canada balsam in thin section size is applied to the cleaned slide using a needle, and the resulting thin section is carefully removed with tweezers, a little faster than the cutting speed (Fig. 108). The thin section, which is now carefully placed onto the microscope slide, is wrapped with Canada balsam and covered with a clean cover slip. To ensure that no air bubbles are trapped, the cover glass is pressed with the inclined compression die, which will allow interfering bubbles to move to the cover glass edge with the flow front (Figs. 67 to 72). It is recommended not to use too much Canada balsam; otherwise the thin section slips under the compression die. It can then wave and float. Rough handling usually leads to false conclusions. Basically, a subsequent cut is always carried out after a thin section to prevent preparation errors. If the subsequent cut shows the same distinctive features as the previous, they are real. The eyepiece (ocular) is first focused to the eye and then the thin section. “Köhler illumination” follows, i.e., focusing the closed field diaphragm to the edge of the image (see also → section, → DSC analysis, → thin section, → thin section device, → defective vision, → filler materials, → glass fibers, → glass pellets, → IR analysis, → Köhler illumination, → crystallites, → crystallite melting temperature range, → plastic materials, → field diaphragm, → microscopic examination, → ocular, → polished sample, → sample preparation, → marginal zone for amorphous plastics, → marginal zone for semicrystalline plastics, → marginal zone, poor in spherulites, → cutting, → core, plastic, → scalpel cut, → universal microscope, and → reinforcing materials).

138

Turbulence



Thin section after a cold treatment

→ Cold treatment in thin sections

Thin section compression

→ Knife angle

Thin section corrugation

Causes for thin section corrugation are high molded part stresses, a dull microtome knife, too much adhesive, or very rarely, a media reaction with the solvent in Canada balsam or Eukitt (see also → molded part stresses, → knives for thin sections, and → knife angle).

Thin section device (microtome)

There are mainly two types of microtomes for producing thin sections: the universal microtome with vertical cutting direction and the sliding microtome with horizontal cutting direction. A thin section device (microtome) must have the following equipment: section thickness selection of 5 to 20 microns, control via foot pedal, plane-parallel sample clamping (clamp), adjustable knife holder (with 0 to 35° declination angle, if possible), TCT knife 160 mm, section D, and its case. All information is based on the universal microtome with vertical cutting direction (see also → thin grinding device).

Thin section knife angle

→ Knife angle

Thin section, comparison to thin ground sample

Thin sections are created in minutes if the plastic can be cut and do not contain any abrasive (dulling) fillers or reinforcing materials such as minerals, glass fibers, glass pellets, or glass flakes. Some samples cannot be cut because they are falling apart or soften (e.g., soft PVC, rigid foams, elastomers, and PMMA). Thin ground sections take a considerably longer time and are made with abrasive plastics with glass or mineral fillings, elastomers, or rigid foams.

Thin section, types of knives

→ Knives for thin sections

Thread overload

Causes of a thread overload in the plastic are mechanical overload during use, high tightening torque, molded part stresses by processing and manufacture (thread cutting) as well as media attacks by cleaning agents or drilling emulsions. Remedy: Use a torque wrench, use tested media (cleaning agents, drilling emulsion), and store the thread after production in a hot area (see also → media and → tempering).

Time savings in expert opinions (report)

And for difficult customer, see also → report preparation, fast and competent.

TMA analysis

→ Thermomechanical analysis TMA and → analysis of plastic materials

Topography

The topography is the relief (height and depth differences or wave) of the surface of a specimen after grinding or polishing in the preparation technique. The relief always has a surface roughness (see also → contrast processes, → surface errors, → polishing, → surface roughness, and → grinding).

Torpedo

The torpedo is the displacement body at the extrusion head. It causes the counter-pressure, which is necessary for plasticizing, together with the perforated disc, the screen packs, and jam bushing (see also → extrusion and → plasticization).

TPE elastomer

→ Thermoplastic elastomer (see also Fig. 195)

Transmitted light

→ Contrast processes

Transmitted light illumination

→ Fig. 106

Tube lens

The tube lens in the hatch optical path produces the intermediate picture and reduces the focus of light rays on an acceptable extension length (see also → aperture, → microscope, → hatch optical path, and → optical path of the pupil).

Turbulence

Turbulence is a swirling of the molding compound during the injection into the mold, with the formation of, for example, hot-cold mixtures and hot-cold streaks. Causes of turbulent mold filling are usually a high injection pressure and an unfavorable gating (design fault). A viscosity increase brings, in rare cases, an improvement by reducing the molding compound temperature. In turbulence, a filling study is always recommended. Hot-cold mixtures include intermixings of cold marginal zones with the plastic core. The holding pressure here only has little significance, except at a very fast holding pressure of the molding compound (see also → injection pressure, → injection, → filling study, → hot-cold mixture, → hot-cold streaks, → inversion layers, → holding pressure, → marginal zone for amorphous polymers, → marginal zone for semicrystalline plastics, → marginal zone, poor in spherulites, and → core, plastic).

139

Definitions

Technical Terms


Tweezers

Technical Terms


Tweezers

The tweezers (Figs. 103 and 108) are made of stainless steel and have tapered, exactly closing tips, with no sharp edges (see also → thin section).

Definitions

Ultraviolet radiation Plastics age in outdoor weathering. They lose their gloss, color, and strength; they chalk and show migration, erosion, cracks, and delaminations. Aging is determined by the intensity of radiation of the sun (UV radiation in outdoor weathering) in the ultraviolet range (UVA, UVB, UVC, 295 to 400 nm), in the visible range (VIS of 420 to 720 nm), and in the infrared range (IR over 720 nm) as well as the duration of irradiation. In particular, the shortwave UV region has an accelerating effect on aging. It can preferably cleave macromolecules with double bonds. The IR content (temperature) leads to heat-induced changes, and the VIS content has the least effect. Also, ionizing radiation (-, -, or -radiation) attacks the plastic surface (see also → aging and → weathering, artificial). Universal microscope

A universal microscope (see Figs. 104 to 107) is a stereomicroscope with a much higher magnification and resolution than a macroscope. A disadvantage, however, is the much smaller working distance between the sample and the objective. It is a microscope with most or all of the contrasting options and is therefore universally applicable (see also → field glass principle, → Greenough principle, → contrast processes of microscopy, → macroscope, → microscope, → microscopic examination, → microscope parts, → stereomicroscope, and examination, comparing).

UV radiation

→ Ultraviolet radiation

UV spectroscopy

A quantitative analysis of additives is performed with UV spectroscopy (see also → additives and → analysis of plastic materials).

UV stabilizer(s)

UV stabilizers delay the degradation of plastics by ultraviolet radiation by neutralizing free radicals and therefore prevent rapid aging (such as vitamins).

Vacuoles and blowholes

Vacuoles are single or closely located, cavernous, fissured vacuum chambers (shrinkage cavities) in the molded part, often in the area of mass accumulations. They are formed by a partial lack of holding pressure when the sprue freezes and the holding pressure cannot press enough molding compound into the tool to compensate for shrinkage from the residual mass cushion, or in a tough molding compound flow through glass fibers. Vacuoles, which are located densely under the molded part surface, often produce sink marks. If there is a vacuole and a marginal zone with a lack of spherulites (greater than 80 microns), then in most cases the mold temperature was too low, the sprue is frozen, and thus the holding pressure is ineffective. During cooling, the molding compound in the mold shrinks and the holding pressure must guide molding compound to compensate for shrinkage. If this is not possible, vacuoles develop (see also → sprue, → sink marks, → microvacuole, → holding pressure, → marginal zone in amorphous plastics, → marginal zone in semicrystalline plastics, → marginal zone, poor in spherulites, → residual mass cushion, → shrinkage, and → mold temperature). Blowholes, however, are single or divided into bead-like, balloon-like smooth over-pressure spaces due to outgassing or entrained air. They are caused by outgassing of ingredients (moisture, monomer, or thermal decomposition), entrained air from the feed zone (at low nozzle pressure or knocked-out nozzle), insufficient degassing (vented screw), inadequate mold venting, thermal decomposition (overheating, high friction), poor predrying (moisture in the molding compound), or in a rapid injection mold at a molding compound temperature that is too low (see also → moisture in the molding compound, → friction, → monomer, → predrying, and → decomposition, thermal). Vacuoles are caused by shrinkage. The molded part weight remains constant, but the molded part dimensions can decrease because the density increases in places. Blowholes indicate an outgassing in the plastic of entrained air (see also → report preparation, fast and competent).

Vapor deposition

Vapor deposition on plastic surfaces protects against light, UV, and media influences. Before a vapor deposition with metals (Al, Au, Ag), the wettability of the plastic surface has to be increased by flaming, chemical etching, or corona treatment (see also → surface refining).

Ventilation, insufficient

→ Venting, → deformation, → diesel effect, → filling study, → plastic deformation, → decomposition, thermal

Venting (mold venting)

Good ventilation improves the accuracy of reproducing the surface and the mold filling rate. Burns can occur if venting during the injection of the molding compound is not sufficient. Then venting ducts should be installed into the mold or existing ones should be enlarged by polishing (see also → molded part quality and → filling study).

140

Wear



Vicat temperature

The Vicat temperature is measured with a Vicat measuring system and determines the thermal stability of a plastic material (see also → analysis of plastic materials).

Victoria blue (coloring agent)

→ Coloring

Vignetting

Vignetting is a pinhole effect in the microscope or an edge shadow in the visual field.

Viscosity

The viscosity (resistance) of the molding compound increases when the injection speed, molding compound temperature, mold temperature, and viscosity number VN decrease (see also → injection rate, → molding compound temperature, → viscosity number, and → mold temperature).

Viscosity influence

→ Glass fibers, → filler materials, and → reinforcing materials

Viscosity measurement

→ Viscosity number and → analysis of plastic materials

Viscosity number VN

At a viscosity measurement, the viscosity number VN is determined during the passage through a measuring capillary. The viscosity number indicates the average molecular weight, and indicates, compared to the granulate, the macromolecule degradation of the molding compound at a processing injury. More or less significant macromolecule degradation normally develops in injection molding or extrusion (chain degradation). This increases the VN value (see also → viscosity).

Visual awareness region, microscopic

The entire field of vision of the microscope is not consciously detected. The conscious area is strictly limited when viewing a specimen under a microscope and corresponds approximately to the diameter of the fovea in the eye. This is also the area of the best color vision. So, only the well-defined, direct view (in the 2° fovea area) is aware and brings knowledge. Therefore, the sample should be exactly “scanned point by point” with the eyes during microscopy, and even the slightest anomaly area should be observed. A reflection on the possible cause and prevention facilitates then the technical term retrieval and comparison with the figures in the encyclopedia (see also → eye, → fovea, → report preparation, fast and competent, and → microscopic examination).

Visual examination

In a visual examination, a sample assessment is only done with the eye without magnification through optical devices such as a magnifying glass or a microscope (see also → report preparation, fast and competent, and → microscopic examination).

Volume shrinkage

The molding compound shrinks in all directions towards the inside during cooling in the mold (see also → molded part stresses, → shrinkage, and → vacuoles).

Warp(s)

→ Cold flow line, → cold flow, → paint warp, and → streaks

Warpage

Delay leads to a mold and dimensional change that can cause warpage. Warpage also develops through mass flows with inhomogeneous density distribution and varying flow rate, molded part stresses, high pressure, cold processing, design errors, lower processing temperatures, orientations of filler and reinforcing materials, poor demoldability (draft angles are missing), uneven mold temperature, high holding pressure to the end, or long holding pressure time (size, start, and timely end empirically determined), premature demolding or free-fall demolding onto conveyor belt (see also → demolding onto conveyor belt, → molded part tensions, → free-fall demolding, → filler materials, → design error, → mass flows, → holding pressure, → holding pressure time, → holding pressure error, → orientation, → processing, cold, → reinforcing materials, and → mold temperature).

Water bath (extruder)

The external surface of pipes is compressed during calibration through a drawing aperture and quickly frozen in a water bath (compressive stress), whereas the noncooled, warmer internal pipe surface further shrinks (tensile stress). The tension drop decreases between the external pipe and the internal pipe surface at a heat exposure of 150 °C. Furthermore, the external diameter of the pipe and also the “tempered” internal diameter of the pipe increase (spring back) with decreasing pressure tensions. Therefore, internal axial cracks sometimes develop there (see also Fig. 403, → axial cracks in the inner surface of a pipe, → extrusion, → link chain, and → drawing blend).

Wear

Reinforcing materials in the molded parts reduce wear during use, but increase wear in the machine and in the mold. Wear is, for example, mechanical degradation in plastics processing machines and molds due to abrasive filler and reinforcing materials in the plastic (see also → degradation, → filler materials, and → reinforcing materials).

141

Definitions

Technical Terms



Technical Terms



Accelerated aging is achieved through artificial weathering. The exposure time depends on the desired lifetime. An often used artificial weathering example with a weathering dose of 8000 MJ/m takes a xenon tester beta LM 4074 hours and is approximately equivalent to 4.8 years of outdoor exposure in central Europe. A sample of 68 × 50 mm is cut out of a plate or a molded part and is weathered in a xenon tester beta LM according to DIN EN ISO 4892-2 as follows: Clock synchronization at Eglob = 550 W/m2 ± 10%, EUV = 60 ± 12 W/m2, sample chamber temperature = 35 °C, relative humidity (RH) = 65 ± 5%, black standard temperature = 60 ± 3 °C, white standard temperature = 40–45 °C, rain cycle = 18/102 (18 min irrigation, 102 min drying), equipped with 3 Xenochrome filter 300.

See also DIN EN ISO 4892-2

One year of outdoor weathering

About 833.33 equipment hours at HUV = 180 MJ/m2

Eglob

is the global irradiance at 400–800 nm (UVA, UVB, UVC, and visible light)

EUV

is the UV irradiance in the unit at 300–400 nm (UVA, UVB)

HUV

is the average annual dose UV outdoors

Definitions

Usually after 8000 MJ/m2 of artificial weathering, a measurement of color fastness (authenticity number) of the sample with the gray scale follows. By most standards, the color fastness has to reach the authenticity number ≥ 3 with the gray scale ISO 105-A02. A measurement of color change according to the CIELAB system with DIN 6174 with the 2° or 10° standard observer usually takes place as well. A spectrophotometer (colorimeter) measures the color values X, Y, and Z and calculates the color coordinates L*, a*, and b*. These are the three axes in the CIELAB color space, as well as the three coordinates for the color position. The color coordinates a* and b* are in the color plane and determine the color space, together with the height L* of the chromaticity (the hue). –a*max

Green

–b*max

Blue

+a*max

Red

+b*max

Yellow

–L*max

Darkness, color black

+Lmax

Brightness, bright, color white

Da*

Measured value difference (red-green axis) between –a*max and +a*max

Db*

Measured value difference (yellow-blue axis) between –b*max and +b*max

∆L*

Measured value difference (brightness axis) between –L*max and +Lmax

∆E*

Color distance, measured from the color measurement values Da*, Db*, and the brightness value ∆L*

See also → additive, → aging, → aging protection, → causes for aging, and → ultraviolet radiation. Webs (plastic burr)

A web is a sheet-like protrusion in the molded part seam. Common terms are burr, web, or ridge. Causes are a sufficient mold clamping with film-like mass discharge in the mold separation (formerly called separation layer) at high injection pressure and/or high molding or mold temperature. This happens, for example, when the injection molding machine and the clamping force for the shot weight are too small, at a displacement of the mold separation through rejected guide pins or in a too-small spring constant of the bars and the mold (see also → shot weight, → parting plane, → mold separation, → mold clamping, and → clamping force).

Weight change

A weight change (weight deviation) occurs in molded parts through a too-high injection and holding pressure (over-injecting) or a low, early dropped or lack of holding pressure. Causes and effects can be found at → injection speed, → weight change, → material residue transfer, → holding pressure, → holding pressure error, → over-injection, → mold venting, and → mold filling, poor). A flow line is formed in an unexpected range at an unexpected confluence of mass flows, for example, a core offset. A flow line is also created, however, in an expected area, for example after a core flowing or at the confluence of two or more mass flows (see also → weld line number, → reversal of the flow front, → core offset, and → mass flows, leading).

142

Welding errors


Technical Terms


Weld line (with or without air induction)

The term “weld line,” as defined below, refers to where two or more flow fronts meet during injection molding. “Binding seam,” “flow line,” or “sealing line” might also be used in this context. However, “weld line” can also be used to denote the seam (welding seam) formed when plastics are subjected to welding processes such as heating element welding, ultrasonic welding, or high-frequency welding. A weld line develops at an expected point by the confluence of the flow fronts of at least two mass flows during injection, which “weld” with a V-shaped surface indent (notch) (Fig. 31). The same applies to a weld line with air induction (Fig. 269) and a strong V-shaped surface indent (electroplating error). If cracks develop next to instead of inside the weld line, it indicates a media attack.

In plastic sleeves, core displacements can occur at high injection speed, decentralized gating, or unfavorable distribution of the mold temperature. Then asymmetrically leading mass flows that generate unnecessary weld lines are formed. The confluence of two mass flows forms a single line I-weld line (Fig. 30), three mass flows form a three-lined Y-weld line (Fig. 159), and four mass flows form a fourlined X-weld (see also → injection pressure, → flow line, → flow resistances, → molding compound, cold, → electroplating error, → mass inversion (with and without induction), → glass fibers, → notch, → notch effect, → core flowing, → core offset, → media attack, → surface roughness, → roughness, and → reinforcing materials). Weld line number

For a parallel confluence of form molding compound flows, which flow together rectified, in a flat or curved flow level after a pressure buildup, the following applies: Weld line = number of mass flows – 1, and in a cylindrical flow level (pipe), weld line number = number of mass flows. The weld line number for equidistant sprues (ideally) is also calculated. In a flat or curved flow level, the following applies: Weld line number = sprue number – 1, and in a cylindrical flow level (pipe), weld line number = sprue number. For example, between three evenly spaced sprues A1, A2, and A3 (ideally), the following develops: two weld lines in a flat or curved flow level and three weld lines in a cylindrical flow level (pipe). If a weld line is located between two sprues A1 and A2, but closer to A2, A2 has a higher resistance to flow (or longer flow path). Then a filling study is recommended, and if this results in no improvement, mold synchronization is recommended. The holding pressure does not noticeably influence the weld line number (see also → sprue, → weld line, → filling study, and → mold synchronization).

Weld line strength

→ Weld line, → molding compound temperature, and → mold temperature

Welding aids

Welding aids (such as PVC powder, PE and PVC welding rods) are materials that allow a weld connection or even facilitate it. For example, in the production of car door panels, PVC powder is sprinkled on cardboard and welded with PVC films in a high-frequency welding process.

Welding errors

Welding errors in pipes are caused by unwinding resistance from a coil; lack of acclimatization outdoors; flexural, compressive, and tensile stresses during installation; residual stresses (high); fixed points (unfavorable, with shrinkage and thermal stresses); foreign particles; air bubbles; MFR values of the joining partners (different); post-crystallization (stress increase); pigment streaks; welding tools (wrong); welding parameters (wrong temperature, pressure, and time); welding (uniaxial in tight building shaft); and precleaning (“oxide layer” not removed). Tensile stresses are caused by weld line cooling during the pipe fixation or during pipe installation from a coil into a pipe trench without guide rollers and acclimatization (adjusting the pipe temperature to the installation temperature). A cold coil has a higher unwinding resistance when unwinding in the building shaft; therefore, the pipe bends, for example, up. The unwinding resistance increases with the exposure time. It is especially high when the temperature decreases and when the winding radius is small.

143

Definitions

Causes for weld lines are leading molding compound flows through different flow resistances (flow path lengths, design error, injection pressure, wall thickness change, roughness), and cooling of the molding compound flowing around the core, core offset, and sprue number. A weld line is always a potential weakness. The flow fronts meet, through a volume expansion during filling, perpendicular to each other and are “welding.” With increasing pressure and temperature, the strength of the weld increases and its visibility decreases. If the “welding temperature” and “welding pressure” drop, the strength of the weld line decreases and the visibility increases. This creates a V-shaped notch and, at load, a crack due to stress concentration. A poor weld line has a deep notch and a reduced strength. Fillers and reinforcing materials are often deposited in the weld line and are debilitating. There, glass fibers tend to be in parallel layers. Therefore, weld lines in a main stress range can be avoided in a constructive way.


Welding errors

Technical Terms


Welding errors

These statements can be analogously applied to the welding of plates and molded parts (see also → internal stresses, → molded part stresses, → foreign particles, → glass transition temperature, → hot air treatment, → air inclusion, → mass accumulation, → media attack, → MFR analysis, → holding pressure, → hold pressure, → holding pressure error, → lack of holding pressure, → post-crystallization, → post-shrinkage, → pigment streaks, → relaxation, → welding aids, → tempering, and → heat exposure).

(continued)

→ Hot air treatment

Wettability

The higher wettability of a plastic surface improves the adhesion of paints and adhesives (see → flaming, → wetting test, → electrostatic surface treatment, → chemical baths, → corona treatment, and → primers).

Wetting agent test (DIN ISO 175)

In the wetting agent test (stress test), the molded part to be examined is immersed in a wetting agent, and after 5 to 15 min at 10-fold magnification microscopically, it is examined for cracks. The developing cracks can usually only be seen after the swelling has decreased (wetting agent evaporation). If high internal and surface stresses are present, significant deformations (shrinkage) at the surface and cracks develop after only 5 minutes. If the fine, often barely visible cracks occur after 15 minutes, small internal and surface stresses are present. The longer the wetting agent is present, the deeper it penetrates. Then even stresses (molded part stresses) from deeper areas are visible. The earlier the cracks occur, the greater the molded part stresses. Caution: in machining sample preparation, stresses can be released, so it is recommended to use whole specimens. Wetting agents are stress crack causing, weak solvents for plastics. With the wetting agent test (DIN ISO 175, determination of the behavior towards fluids, including water), the size of molded part stresses and wettability (paintability) of the molded part surface is tested with a test liquid (wetting agents). For example, if present, three whole molded parts (samples 1, 2, and 3) should be submerged into the wetting agent, and sample 1 should be pulled out after 5 min, sample 2 after 10 minutes, and sample 3 should be removed after 15 minutes. The samples should dry overnight if possible, so that the swelling caused by the wetting agent disappears. Then, cracks are often first visible (see also → wetting test, → molded part stresses, → media that can cause stress cracking, → wetting agents, → surface stresses, → sample preparation, machining, and → stress crack test).

Wetting agents

→ Media that can cause stress cracking, → molded part stresses, and → wetting agent test

Wetting test

With a wetting test, the exposed plastic surface is successively wetted with 8 test pins of 30 to 44 mN/m (or seven bottles with test inks of 28 to 56 mN/m). The desired wettability corresponds to the underlined test ink, which stops for two seconds without extremely sharp stops. Caution: for the examination, depending on the tolerance, either blue or red test pens (ink test) are used, since a mixture results in different measured results. Before the examination of the wettability of a molded part, any existing coating is removed with an adhesive tape. To examine the wettability of the exposed surface, test pins are preferably used. For example, the wettability of a good pretreated ABS surface 34 mN/m (millinewton/ meter) should be reached (see also → wettability, → adhesive tape test, → wetting test).

Definitions

Welding seam, examine

Source: Company Arcotest Oberflächentechnik GmbH, Rotweg 25, 71297 Mönsheim, Germany, Tel: +49 7044/9212-0

Wollaston prism

→ DIC prism and → contrast processes in microscopy

Wood plastic composites

→ WPC plastics (see also → plastic materials)

WPC plastics

WPC plastics (wood plastic composites, Fig. 196) are used in the construction, furniture, automotive, and toy industries. They are materials for flooring, fences, and panels. In WPC products, the properties are specifically influenced by a variation of the wood content. Matrix materials are polypropylene (PP) or polyethylene (PE). Adhesion promoters (compatibilizers) improve cohesion between the polar wood fiber and nonpolar plastic matrix. Additionally, other processing aids are required: antioxidants, fungicides, masterbatch, and UV stabilizers. For reinforcement, the following may be used: bast fibers made from hemp, wood fibers, kenaf, and fruit fibers from coconut, hard fibers from pineapple, esparto, or seed fibers from cotton or kapok.

Yellow discoloration of PVC

In the yellowing of a PVC window profile surface, antioxidants move from the stabilizer to the surface. The yellowing recedes during extended exposure (see also → surface discoloration).

144

Chapter 3 Quality and Damage Figures This chapter contains 588 figures from many areas of plastics technology, each with an explanation of the cause of damage, and in 74 historically evolved subchapters. Each page has a header with a page number and a subchapter (LM or SEM) and contains two images of damage causes and damage avoidance, contrast processes, magnifications, type of plastic materials, molded part term, figure numbers, and the keywords from the glossary. These analyses were performed with various optical microscopes and a scanning electron microscope. Searching of quality and damage figures is done with the figure number after the technical term in the Chapter Glossary or directly in the alphabetically arranged subchapters in the following table. Table of LM and SEM subchapters: Subchapter Adhesive Bonding Blowholes Blowholes Bubbles Burning Cold flow Cold flow Coloring Comparison Conglomerate Contrast Cracks Cracks Crystals Crystals Damage Damage Deformation Delamination Delamination Design Diffusion layer Discharge Electron beam Embedding Equipment Extrusion Fillers Films Foams Foams Fractures Fractures Fungi Fungi Glass balls Glass fibers

Figure No. 172–176 221–230 357–357 36–42 537–539 143–168 350–350 79–79 540–556 351–351 183–191 382–419 369–370 192–194 352–354 557–564 377–381 53–63 64–65 324–324 177–182 66–66 80–81 325–325 73–78 103–110 82–85 328–330 86–98 420–420 371–374 43–52 312–323 295–298 365–368 340–341 111–122

LM/SEM LM LM SEM LM LM LM SEM LM LM SEM LM LM SEM LM SEM LM SEM LM LM SEM LM LM LM SEM LM LM LM SEM LM LM SEM LM SEM LM SEM SEM LM

Subchapter Glass fibers Granulate Implant Isochromatics Laminating Lasering Layers Marginal zone Mass inversion Mass swivel Media Media attack Metal abrasion Metallization Microbes Mold Over-injection Painting Painting Particle Particle Plastic materials Reinforcement Spherulites Sprue Streaks Stresses Thin section Thread Vacuoles Vacuoles Warpage Warps Weathering Weathering Weld line Welding

Figure No. 331–339 123–136 342–349 137–142 169–171 214–220 421–444 299–306 99–102 231–232 233–262 358–360 263–264 265–278 361–362 574–588 511–515 197–213 355–356 279–294 363–364 195–196 565–567 501–510 01–05 445–460 485–500 67–72 326–326 516–536 375–376 568–573 327–327 06–27 307–311 28–35 461–484

LM/SEM SEM LM SEM LM LM LM LM LM LM LM LM SEM LM LM SEM LM LM LM SEM LM SEM LM LM LM LM LM LM LM SEM LM SEM LM SEM LM SEM LM LM

LM = light microscopy (or optical microscopy) SEM = scanning electron microscopy

For search examples, see pages X–XII.

145


LM Subchapter: Sprue

Figure 1 ••Gate stresses, ••Shrinkage, ••Mold temperature is too low

Figure 1, PP water protection bell (M = 12, AL) pinpoint gate with high gate stresses (floral structure). The frozen gate stresses cause, after demolding, a strong shrinkage and a wavy surface in the gate area. This phenomenon was first observed after a seven-day-use period. Cause was a mold temperature that was too low. Such a gate “flower” usually only develops in thin-walled molded parts.

Figures & Text

Gate filament

Figure 2, PE nozzle (M = 10, AL) with gate sink mark (red arrows) orange skin, and cold-flow areas around the deeply torn pinpoint gate. This indicates a too-low temperature of the mold and/or molding compound. The gate filament indicates a premature mold ejection, and the gate sink mark implies an insufficient holding pressure time.

146

Figure 2 ••Gate filament, ••Gate sink mark, ••Demolding, too early, ••Cold-flow areas ••Holding pressure, dropped too soon ••Orange skin, ••Pinpoint gate, deeply torn


LM Subchapter: Sprue

Figure 3 ••Runner with 10 mold cavities, ••Symmetry balance through polishing, ••Flow paths, different, ••Mold cavity filling has to be optimized

Figure 3, PA/PTFE runner (M = 1 : 1) with 10 mold cavities and symmetry balance through polishing. The molded part quality improves in all 10 cavities through balancing the gates in the runner. For this, the gates were partially polished to varying degrees because different flow path lengths are present between the direct gate and the mold cavities. The goal was an equally fast filling of the mold cavities.

Figure 4 ••Forming, cold, ••Gate area with orange skin, ••Weld line with crack

Figures & Text

Crack

Figure 4, POM clamp (M = 18, AL). Through the gate area (left eye), a crack develops in the weld line, and the molded part surface shows a very cold impression of the mold surface (see also → weld line and → orange skin).

147


LM Subchapter: Sprue/Weathering

Figure 5 ••Pinpoint gate is torn, ••Demolding somewhat late

Figure 5, PA6 molded part (M = 20, AL) with pinpoint gate. The pinpoint gate is torn out to the left of the picture. This indicates a somewhat late demolding in connection with a cold mold temperature. Such a visual error usually leads to complaints, particularly when a surface finishing follows, such as painting, plating, or metallizing.

Figure 6 ••Weld line is torn, ••UV exposure outdoors, ••Cleaning agent attack

Figures & Text

Torn weld line

Hair cracks

Fine cracks Figure 6, Bottle stopper, made of glass ceramic (M = 31, AL), damaged part as delivered, with white centering cap made of PP (white) and red thermoplastic elastomer (TPE) sealing washer. By exposure to UV radiation during outside storage and solvent-containing cleaning agents, the polymer matrix is embrittled, arising from hair cracks, and cracks at the weld line of the TPE sealing washer.

148


LM Subchapter: Weathering

Figure 7 ••Samples and insular microcracks after media exposure and 15,000 MJ/m2 weathering, ••Shrinkage stresses due to manufacturing

Cracks

Figure 7, PA/PTFE sheet (M = 1 : 1) with samples and microcracks after media exposure and a weathering dose of 15,000 MJ/m2 in a Xenon tester 1200 CPS. The insular microcrack formation was also benefiting from an increased molded part stress in the surface due to shrinkage stresses and a too-rapid cooling in injection molding.

Figure 8 ••Surface, weathered and original

Figures & Text Figure 8, PVC-U window profile (M = 31, AL) with weathered surface after 8000 MJ/m2 in a Xenon tester beta LM. The original surface can still be detected on the left side of the figure (see also Fig. 9).

149



Figure 9 ••Weathering, 8000 MJ/m2 (4074 h), ••Internal stresses, ••Level of gelling, ••Surface roughness, ••Heat treatment with hot air gun

Figure 9, PVC-U window profile section (M = 31, Al) after 8000 MJ/m2 in a Xenon tester 1200 CPS. A heat treatment using a hot air gun at 230 °C generates a highly roughened surface profile (approximately 45° to the extrusion direction) through released internal stresses, following the flow fronts. The surface roughness was created through a low level of gelling, which should be at about 60 to 70% (see also Fig. 8 and → level of gelling).

Figure 10

Figures & Text

••Specimens after weathering 8000 MJ/m2 (4074 h), ••Laminating with decorative film, ••PMMA layer 50 µm

Figure 10, PVC-U window profile, laminated with decorative film (M = 28, AL). After 8000 MJ/m2 of artificial weathering in a Xenon tester 1200 CPS, the 50 µm thick PMMA layer started to develop cracks, artifacts (outbreaks), and peel off the surface on the decorative foil (lamination) (see also → weathering, artificial and → laminating).

150



Figure 11 ••Weathering 9818 MJ/m2 (5000 h), ••Contrast process AL combined with DL, ••Hair cracks after weathering

Figure 11, GF-UP sheet, transparent (M = 20, AL + DL). The cracks (hair cracks) in the sample surface developed after 5000 hours of weathering in a Xenon tester 1200 CPS. The crack depth is no deeper than about 35 µm. During recording, a low level of transmitted light has been combined with incident light.

Figure 12

Figures & Text

••Outdoor weathering, 4 years, ••Surface with dirt deposits, ••UV stabilization is poor

Figure 12, PP lounge seat (M = 100, AL) with UV stabilization. A rough PP surface developed after four years of outdoor weathering in Würzburg, Germany. Thus the dirt deposits cannot be removed with the cleaning products that were recommended by the manufacturer, and the rough PP surface retained a gray appearance.

151



Figure 13 ••Weathering 8000 MJ/m2 (4074 h), ••Microcracks, ••Bend specimen with cracks

Figure 13, EPDM gasket profile for PVC windows (M = 30, AL). After 8000 MJ/m2 artificial weathering in a Xenon tester beta LM the surface embrittled and caused formation of cracks and microcracks. An assessment of whether cracks are present or not is done by a combination bending of the sample ends in soft samples. Then the cracks opened and become gapingly visible.

Figure 14

Figures & Text

••Outdoor weathering and the influence of media after two years, ••IR analysis, ••Migration of plasticizers, ••Microcracks, ••Blackening, ••Embrittlement

Figure 14, PVC mesh chair with Al frame (M = 1 : 1) after two years of use in outdoor weathering. The PVC braid is colored black, embrittled, and has cracks, particularly on the left arm edge and on the arm-rest. With IR and DSC analyses of the braid, plasticizer migration was detected in the disputed areas through a decrease of the plasticizer from the inside out. The causes of cracks and blackening are therefore plasticizer relocation through migration and the reaction of the oily substance with effects under sunlight and media, such as cleaning agents, sun, oils, and gases (see also → IR analysis, → DSC analysis, and → migration).

152



Figure 15 ••Outdoor weathering for 22 years, ••Microcracks 500 µm deep, ••Prognosis for the future

Figure 15, ECB roofing film (M = 15, AL) with microcracks after 22 years of outdoor weathering in the climate of Würzburg on the roof of the South German Plastic Processing Center (SKZ) at 45° angle of radiation from the south. The surface of the ECB roofing film was affected to a depth of 500 µm. Prognosis for the future: Assuming the same load, the roofing film will remain sealed for a long time. ECB is ethylene copolymer bitumen.

Figure 16

Figures & Text

••Weathering 3927 MJ/m2 (2000 h), ••Hair cracks after weathering, ••UV stabilizer

Figure 16, PC facade plate, transparent (M = 100, DL + DIC) with UV stabilizer. Hair cracks appeared in the surface after 2000 hours of artificial weathering in a Xenon tester 1200 CPS (see Figs. 17 and 18).

153



Figure 17 ••Weathering 1964 MJ/m2 (1000 h), ••Homogenization, poor, ••Microcracks, ••Hair crack area after weathering, ••Media influence, teardrop-shaped

Figure 17, PC facade plate, transparent (M = 50, DL) with UV stabilizer. Flower-like microcracks and hair-crack areas are already formed in the surface after 1000 h of artificial weathering in a Xenon tester 1200 CPS. Causes are insufficient homogenization (distribution) of the UV stabilizer with partial erosion due to irrigation water, and a previous teardrop media exposure of the facade plate in use (see also Figs. 16 and 18).

Figure 18

Figures & Text

••Weathering 3927 MJ/m2 (2000 h), ••Hair-crack area, transition

Figure 18, PC facade plate, transparent (M = 200, DL) with UV stabilizer. The figure shows, after 2000 hours of weathering in a Xenon tester 1200 CPS, another detail within a transition area (red arrows) between a circular hair crack area, as in Fig. 17, and a subsequent molded part surface with many hair cracks, as in Fig. 16. The circular hair-crack area (on the left side in the figure) shows significantly more cracks. Different cracks are caused by the influence of the weather, different molded part stresses in the surface, different temperatures in the injection mold, a drop-shaped media load, and poor distribution of the UV stabilizer during homogenization.

154



Figure 19 ••Axial cracks after 14 months of outdoor weathering in a composite heating pipe, ••Pipe expansion

Figure 19, PE-RT/AL/PE-RT composite heating pipe 18 × 2 mm (M = 6, AL). After about 14 months of exposure outdoors, with temporary direct sunlight, at 2.5 bar water pressure, an expansion around the screws and axial cracks developed in the outer layer to the underlying AL-layer (see Fig. 20).

Figure 20 ••Lip crack in a pipe after about 14 months

Figures & Text Figure 20, PE-RT/AL/PE-RT composite heating pipe 18 × 2 mm (M = 6, AL). After about 14 months outdoors with intermittent direct sunlight, a typical lip crack in the axial direction developed at 2.5 bar water pressure in a different area (see Figs. 19, 390, and 412).

155



Figure 21 ••Weathering 8000 MJ/m2 (4074 h) in accordance with DIN EN ISO 4892-2, method A (equivalent to RAL-GZ 716/1, section 1), ••Weathering parameter

Figure 21, EPDM window profile seal (M = 16, AL). The delivered good part (8000 MJ/m2, 4074 h) was subjected to artificial weathering in a Xenon LM beta tester, according to DIN EN ISO 4892-2, method A (equivalent to RAL-GZ 716/1, section 1). The weathering parameters were synchronization at EUV = 60±12 W/m2, PRT = 35 °C, relative humidity (RH) = 65±5%, SST = 60±3 °C, WST = 40–45 °C, cycle = 18/102, filter Xenochrom 300. The change by weathering can be seen in Fig. 22 (see also → weathering).

Figure 22

Figures & Text

••Damage reenactment, ••Aging test is important, ••Fading after weathering, ••Weathering 8000 MJ/m2 (4074 h), ••Cracks, deep, ••Embrittlement after weathering

Base

Figure 22, EPDM window profile seal (M = 16, AL), damaged part. The good part from Fig. 21 strongly fades and develops deep cracks with embrittlement after 8000 MJ/m2 artificial weathering in a Xenon tester beta LM according to DIN EN ISO 4892-2, method A (equivalent to RAL-GZ 716/1, section 1). After five years of service life, the window profile seal showed the same damages as the damage reenactment in the Xenon tester. The example clearly shows the importance of an aging test before application outdoors.

156



Figure 23 ••Brown coloring in outdoor weathering creates a temperature increase, ••Light transmission decreases, ••UV stabilization poor, ••Embrittlement through thermal decomposition

Figure 23, PVC roofing element (M = 20, DL), 10 µm thin section. A UV attack of the surface (weathering side) of the initially transparent PVC roofing element causes an increase in temperature and a decreasing light penetration due to browning. In particular, the temperature increase during extrusion causes chain degradation in the temperature-sensitive PVC and shortens the lifespan through thermal decomposition. The cause was poor UV stabilization.

Figure 24

Figures & Text

••UV exposure to fluorescent lighting is often underestimated, ••Cracks, ••Damage effect reinforced by molded part stresses and media

Figure 24, SB housing (M = 31, AL) with cracks through a commercial double lamp with white-light fluorescent tubes in a production plant. The housing was at a distance of about 1.20 m from the light source, and the cracks were observed after about 3.5 years. The example shows an often-underestimated UV exposure by fluorescent tubes. The effect can be enhanced if molded part stresses and gaseous media loads are added.

157



Figure 25 ••Weathering 8000 MJ/m2 (4074 h), cracks, ••Retain samples, ••Damage reenactment also results in cracks

Figure 25, PUR spoiler (M = 50, AL-DF). In a reenactment of the damage, after 8000 MJ/m2 (4074 h) artificial weathering in a Xenon tester 1200 CPS, exactly the same cracks develop in the spoiler surface, as it would be through a UV attack during use. The damage reenactment is done for the damage evidence. Therefore, good parts (retained samples for damage series) are exposed to the same damaging influences (see also → damage reenactment).

Figure 26

Figures & Text

••Weathering, 4074 h, ••2C polysulfide joint sealant, ••Matrix strongly attacked

Figure 26, Polysulfide joint sealant 2C, sample 3 (M = 6, AL). Three specimens were subjected to artificial weathering for a total of 4074 h: 5 × 400 hours with initial joint width; 5 × 400 hours with strain (+25% of the initial joint width); and 4 × 400 hours with compression (–25% of the initial joint width). In between, there were visual examinations for cracks. As seen in the picture, the polysulfide matrix was strongly attacked after completed weathering (see also Fig. 27).

158


LM Subchapter: Weathering/Weld line

Figure 27 ••Weathering, 4074 h, ••1C polyurethane, ••Matrix attacked

Figure 27, Joint sealant 1C PUR, sample 3 (M = 6, AL). Three specimens were subjected to artificial weathering for a total of 4074 h: 5 × 400 hours with initial joint width; 5 × 400 hours with strain (+25% of the initial joint width); and 4 × 400 hours with compression (–5% of the initial joint width). In between, there were visual examinations for cracks. As seen in the picture, the polysulfide matrix was less affected after completed weathering than in Fig. 26.

Figure 28

Figures & Text

••Weld line, line-like, ••Fiberglass parallel layers, ••Mass flows, two, ••Orange skin

Figure 28, ABS-molded part (M = 6, AL) with orange skin and → weld line (arrows). A weld line “welds” with a V-shaped surface indentation (notch) after core flowing or occurs due to leading mass flows. Poor weld lines have deep notches with reduced strength (notch effect). Fillers and reinforcing materials often accumulate, and glass fibers tend to form parallel layers.

159


LM Subchapter: Weld line

Figure 29 ••Y-weld line, ••Core flowing, ••Mass flows, three, ••Mold, cold

Figure 29, CA sleeve (M = 6, AL) with Y-weld line. It originated in a too-cold injection during core flowing of three confluent mass flows (see also → weld line).

Figure 30

Figures & Text

••Weld line, line-like, close to the gate, ••Molded part, cold, ••Mass flows, two, ••Mold, cold

Figure 30, SB molded part (M = 6, AL) with a weld line that is close to the gate. If a weld line already occurs close to the gate, the molding compound is often generally too cold in comparision to the cold mold temperature (see → weld line).

160



Figure 31 ••Weld line, open, ••Molding compound, cold, ••Mass flows, three, cold viscous, ••Holding pressure, dropped too early ••Mold wetting, poor

Weld line

Figure 31, POM gear (M = 25, AL). New part with open, not injected weld line and poor mold impression (also called mold wetting). The three mass flows, which are forming the weld lines, were already so highly viscous (“thick”) that the weld line could not close anymore. Causes were a too-low molding compound temperature due to a short homogenization time and holding pressures that were dropped too early (see also → weld line and → mold impression).

Figure 32 ••Weld line, circular, unavoidable, ••Bridges with ring binding and weld lines

Figures & Text Figure 32, POM bridge ring (M = 12, AL), damaged part with four bridges. Each bridge has a circular weld line (arrows) through a central gating via the bridges in the ring connection on the outer ring. The weld lines are basically unavoidable here, but can be improved in strength and visibility by increasing the temperature in the mold and the molding compound (see also Fig. 33, → weld line).

161



Figure 33 ••Runner plate centric, ••Ejection damage?, ••Mold marking?

Figure 33, POM bridge ring (M = 12, AL), damaged part, internal detail of Fig. 32. A mold marking or damage through ejection of the molded part is located in the area of the central runner plate (see Fig. 34).

Figure 34

Figures & Text

••Molding compound, inhomogeneous, remote from the gate, ••Thin section through a bridge with weld line, ••Air bubbles in Canada balsam

Bridge

Figure 34, POM bridge ring (M = 12, AL), damaged part. A 10 µm thin section has a distinctly inhomogeneous molding compound through one of the bridges that is remote from the gate in the area of the ring connection. The two dark circular rings in the left half of the figure (top and bottom) are air bubbles in Canada balsam (see Figs. 32 and 33, → embedding media, and → Canada balsam).

162


LM Subchapter: Weld line/Bubbles

Figure 35 ••Mass flows, many ••L/D ratio is too large, ••Counter-pressure is too low, ••Homogenization poor, ••Matrix weakening, ••Structure, inhomogeneous

Figure 35, PE sheet (M = 25, DL). The 10 µm thin section has a noticeable inhomogeneous structure and pronounced pigment streaks. They were created in the extrusion by subsequent coloring of the molding compound and poor homogenization because the counter-pressure was too low. Such errors also occur when the melt temperature, screw speed, or the L/D ratio is too large (L = screw length, D = screw diameter). Distinct pigment streaks between the mass flows can, similar to the weld lines, cause weakening in the matrix.

Figure 36

Figures & Text

••Bulge, ••Molded part surface, rough, ••Over-injection?

Figure 36, PP-GF30 light well (M = 6, AL) with direct gate. The molded part has a bubble-like, rough surface next to the gate and a bulge (red arrows). In the area directly next to the direct gate, the molded part surface adheres to the mold when ejecting (see also the enlarged detail in Figs. 37, 38, and 39, → gate, and → fibrils).

163


LM Subchapter: Bubbles

Direct gate

Figure 37 ••Bulge, ••Microvacuoles, many, ••Direct gate, ••Mold adhesion

Figure 37, PP-GF30 light well (M = 20, AL), details from Fig. 36. The severed gate contains many microvacuoles. In the area next to it (below right), it can be seen that the molded part surface has adhered to the mold (see Figs. 36 to 39 and → microvacuoles).

Figure 38

Figures & Text

••Foreign particles with “poorly welded” edges, ••Homogenization poor?, ••Residual granulate?

Figure 38, PP-GF30 light well (M = 20, AL). A polished sample through the bulge (Fig. 36) of the molded part surface (red arrows) shows that no bubble or layer peeling (red arrows) is present, as initially suspected, but it is a nonmelted, large particle with “poorly welded” edges. This could be a too-cold residual granulate or even a foreign particle, which is hard to melt in poor homogenization (see Figs. 36 and 37, → foreign particles, → homogenization, → residual granulate, and further explanation in Fig. 39).

164



Figure 39 ••Crystallinity (DSC analysis), ••Particle, unmelted, with glass fibers

Figure 39, PP-GF30 light well (M = 20, AL). A polished sample through another particle shows a noticeably higher glass fiber content. The unmelted particle has a higher crystallinity, as evidenced by DSC analysis, and visibly higher glass fiber content. This results in lower particle shrinkage during cooling. The particle seems elevated (as a bulge) in the molded part surface because it is higher in the matrix. The particles in Fig. 38 have a higher crystallinity and lower fiber content. The bulge and bubble-like rough surface in Fig. 36, the bonding in the mold, the many microvacuoles in Fig. 37, and the particle in the figure above have several causes: regranulate (particles) with different glass fiber contents was mixed into the molding compound, the microvacuoles in the gate indicate a partial lack of holding pressure, the poorly welded particle edges prove a too-low molding compound temperature and homogenization time, and the bulge developed through the bonding in the mold during demolding (see Figs. 36, 37, and 38).

Figure 40

Figures & Text

••Laminating film (PMMA 50 µm) with bubble, ••Adhesive application is missing, ••PVC decorative film, ••Heat exposure 150 °C

Bubble Adhesive

PVC-Profile Figure 40, PVC-U window profile section (M = 20, DL) with a 10 µm thin section through laminating on the window profile section. The layer thicknesses of the laminating film are (from top to bottom): 50 µm acrylic sheet (PMMA), PVC decorative film with wood grain, and polyurethane adhesive on the PVC profile. Bubbles formed under the laminating film after heat exposure in a convection oven at 150 °C. The damage was caused by a partial lack of adhesive application.

165



Figure 41 ••Bubble or blowhole?

Figures & Text

Figure 41, TEEE line (M = 25, AL), damaged part. The bubble-like bulge on the TEEE line was a bubble or blowhole, according to the customer. The answer was found with a 10 µm thin section (see Fig. 42) through the complaint area. TEEE is a thermoplastic elastomer, TPE, based on sulfide ether.

Figure 42 ••10 µm thin section through bubble bulge shows no bubble or blowholes, ••Mold damage?

Figure 42, TEEE line (M = 25, AL), damaged part. A 10 µm thin section through the lens-like elevation in Fig. 41 shows that no bubbles or blowholes are present in the area of the red arrows, as assumed by the customer. We suspect the impression of unrecognized mechanical mold damage as the cause of the complaint.

166


LM Subchapter: Fractures

Figure 43 ••Cracks in the crack faces, ••Cracked pipe examination

CR

CR

CR

CR

Figure 43, PVC pipe (M = 8, AL). The crack region in a PVC water pipe has been removed and the crack is forcibly bent 180° until the crack edges are plane-parallel to each other and could be examined under the microscope. In this advantageous arrangement, both crack faces could simultaneously be checked for cracks and the inside of the pipe for microcracks. The crack leading to failure originated in the pipe inside through high molded part stresses. Proof of this is the four cracks (CR). Delaminations by, for example, THF adhesive or cleaning agents were not found, only bright lime deposits and rust particles. Tetrahydrofuran THF is a solvent for PVC, and a THF-adhesive contains up to 30% PVC for bridging cracks (see also → axial cracks in the pipe inside).

Figures & Text

Figure 44 ••Fracture surface with dull spots, ••Homogenization poor, ••Carbon black conglomerate and carbon black streaks

Figure 44, PE-80 pipe fracture surface (damaged part, M = 30, AL) is delivered. In the fracture surface of the drinking water pipe, which was directly examined under the microscope, are very dull, deep-black carbon black conglomerate and carbon black streaks. They are the cause of damage due to a lack of homogenization of the added carbon black masterbatches. As the example shows, a direct examination of a fracture surface, without thin section, can be very informative.

167



Figure 45 ••Fracture centers in PETP, ••Particles distributed inhomogeneously, ••Failure area (cross-section)

Fracture center

Figure 45, PETP fracture center (M = 20, AL-DF) fracture surface (failure cross-section) with fracture centers. The cause of damage is inhomogeneously distributed pigment conglomerates in the form of a mass because 10 µm thin sections revealed the failure areas. Due to the pigment conglomerates, the cross-section failed simultaneously in many areas or sequentially. A common fracture has often only one fracture center (see also Fig. 46, → fracture center, → pigment conglomerate).

Figure 46

Figures & Text

••Fracture center with the start of a crack, fibrils and circular crack front, ••Carbon black conglomerate crack center

Figure 46, PETP fracture center (M = 50, AL-DF), detail of Fig. 45 with a carbon black conglomerate as a fracture center. The inner black circle is a carbon black conglomerate and also the start of a crack. There, the fibrils (stretching tip) are perpendicular due to the force acting on the surface. The fibrils are oriented in the direction of the front of the circular propagating crack to the outer circle and tend to move toward the surface.

168



Figure 47 ••C-PVC fracture center in a burst water pipe with carbon black conglomerate, ••Pipe burst

Figure 47, C-PVC drinking water pipes, burst (M = 25, AL) with a fracture center and carbon black conglomerate in a fracture flank. Since a carbon black conglomerate cannot form a strong bond with the C-PVC matrix, it acted as a weakening foreign body during pressure surges in the pipe wall of a quick-acting valve (single lever handle mixer) in a restaurant. The pipe burst at night and the escaping water flooded the floor and caused severe damage. C-PVC is post-chlorinated PVC.

Figure 48

Figures & Text

••Melt fracture during injection molding, ••Overstretching, cold

Figure 48, PP bottle, manufactured in injection blow molding (M = 6, AL). The cooling time between injection molding and blowing was too long. Therefore, the preform cooled from the thermoplastic range deep down to the thermoelastic range. The melt fracture developed during blowing through the elongation in the part surface (see also → blow molding).

169



Figure 49 ••Core offset (molded part offset) ••Predetermined breaking point, defective, ••Offset in the molded part, ••Mold guidance is rejected

Figure 49, PA6.3 cartridge, fine crystalline (M = 1 : 1, AL) with predetermined breaking cover. This should break at the left and right breaking point at an internal pressure buildup, so that the content (EP epoxy and hardener) flows out of a parallel cartridge together with the accelerator and is mixed in an upstream mixing head. By a displacement of the mold core (core offset), however, the predetermined breaking points are unequally molded. The crack, which developed during the internal pressure buildup, therefore, did not follow the shortest path but inadvertently penetrated deep into the bulge. As a result, the content moved out without mixing and polluted the environment. The cause of damage was thus asymmetric core injection and environmental pollution (see also Fig. 50 and → core offset).

Figure 50

Figures & Text

••Core offset at the predetermined breaking point, ••Asymmetric core injection

Figure 50, PA6.3 cartridge, fine crystalline (M = 1 : 1, AL), detail from Fig. 49, with predetermined breaking cover and core offset. Through the displacement of the mold core (core offset), the right predetermined breaking point was unequally molded, and the crack therefore deepened from the right predetermined breakage point to the right bulge and not through the shortest path. The cause of damage was the asymmetric core injection.

170



Figure 51 ••Shear joint overload by influence of the sun, ••Stress whitening in the shear joint

Stress whitening

Figure 51, PE diesel canister (M = 6, Al). A diesel canister, which is produced in injection blow molding, has a shear joint in the bottom with stress whitening (arrows). The stress whitening developed by an overload of the shear joint as a result of the diesel fuel expanding in the sun.

Figure 52

Figures & Text

••Stress whitening of snap hooks, ••Orange skin, ••Plastic deformation, (low)

Stress whitening

Figure 52, ABS snap hook (M = 25, AL) with stress whitening. It developed by a too-strong bending of the snap hook in the arrow direction during assembly. Also evident are orange skin and a slight plastic deformation in the stress whitening area (see also → orange skin, → plastic deformation, and → stress whitening).

171


LM Subchapter: Deformation

Figure 53 ••Ejecting, too early, ••Deformation, sealing cap, ••Demolding, too early

Figure 53, PE sealing cap (M = 6, AL) with demolding error. The deformed sealing lip (arrows) on the inside of the sealing cap was created by an unfavorable mold release and a premature ejection from the mold (see also → ejecting and → demolding error).

Figure 54

Figures & Text

••Embossing offset, ••Corrugated pipe with folding, ••Link chain

Figure 54, PVC corrugated pipe exterior (M = 6, AL) with embossing offset (red arrows) and folding (blue arrows) on the corrugated pipe exterior. The causes of damage in the shaping of the corrugated pipe were an inaccurate working chain deduction (corrugator) and inaccurately closing mold shells. Furthermore, the shaping of the pipe waves in the extrusion line was done too late because the pipe was already too cool (red arrows). Hence a folding (purple arrows) developed in the embossed wave.

172



Figure 55 ••Structural displacement in PP, ••Holding pressure flow, ••Shear zone with PP spherulites, ••Core, plastic, ••Spherulites sheared

Figure 55, PP filter (M = 100, DL-POL), 10 µm thin section through a shear zone with PP spherulites in the center of the picture. The cause was a structural displacement (shear zone) in the injection-molded part wall. They developed at a good temperature level in the plastic core center of the wall center with a strong holding pressure flow along the pigment streaks (see also → core, plastic).

Figure 56 ••Weld line with shear zone, ••Permeation layer

Membrane

Figures & Text

Weld line

Carrier plate

Figure 56, PA oil tank, rotationally molded (M = 50, DL-POL + -plate) with permeation layer (membrane). The permeation layer prevents foul-smelling oil vapors from escaping. A 10 µm thin section of the oil tank wall with the permeation layer shows a weld line and a shear zone in the vicinity of the heated mold wall (black arrows; see also Fig. 57).

173



Figure 57 ••Spherulite stretching, ••Volume shrinkage

Figure 57, PA oil tank, rotationally molded (M = 50, DL-POL + -plate), detail from Fig. 56 with a 10 µm thin section through the connection seam of the next layer, called the shear zone in Fig. 56. The volume shrinkage between the two layers, which occurs during cooling, caused a spherulite stretching. In rotational molding, the wall construction is usually done in multiple layers (center of the picture; see also Fig. 56).

Figure 58

Figures & Text

••Ejector impression, deep, ••Molded part temperature, high, ••Mold demolding too early

Figure 58, POM clips (M = 6, AL) with deep ejector impressions (arrows) through a premature demolding. Damage was caused by a too-high molded part temperature. Therefore, the ejectors get pressed deeper during removal of the clip from the tool, than in a later demolding of the clip with sufficient cooling.

174



Figure 59 ••Expanding moment for ABS, ••Deflection, ••Electroplated layer is damaged, ••Convection oven, ••Heat exposure 60 °C

Figure 59, ABS round board, electroplated (M = 18, AL), after 4 h heat exposure in a convection oven at 60 °C. In the original countersink of the bore hole, the countersunk head of the used countersunk head screw has been ingrained with a deep groove. This created an expansion moment and a bending of the board in an overlay with a too-high screw tightening torque. This resulted in radial cracks in the slab edge starting at the bore hole that develop on the underside (see also Fig. 60).

Figure 60

Figures & Text

••Electroplated layer with fine cracks, ••Hole edge bulge (plastic deformation), ••Screw tightening torque, high, ••Production, too cold

Figure 60, ABS round board, electroplated (M = 18, AL) after 4 h of exposure in a hot air oven at 60 °C, the bottom of Fig. 59. There, the excessive tightening torque generates a hole edge bulge (plastic deformation) with fine radial cracks in the hard electroplating layer (chromium, nickel, and copper layer), right up to the plastic surface top (see Fig. 59).

175



Figure 61 ••Slip-way deformation, ••Production, too cold, ••Surface pressure, ••Seizure marks, ••Plastic wear, ••Preload of the steel spring

Figures & Text

Figure 61, PA6.6 cover hinge (part damage, M = 6, AL). The hinge (in working position) consists of part 1 and 2. When opening the cover, the slip-way slides from the fixed part 1 and part 2 (Fig. 62) on top of each other and increases the preload of a strong steel spring. The cover is locked in any angular position against closing through friction and a high surface pressure between the slip-ways. After two months of use, slip-way deformations, seizing marks, and plastic wear occurred, caused by the desired high surface pressure. The cause of the damage was not, as suggested by the client, the intentionally high surface pressure, but instead caused by a too-cold production of injection-molding partner (see also Figs. 62 and 63).

Figure 62

Slip way

Deformation

Figure 62, PA6.6 cover hinge (damaged part, M = 6, AL), part 2 from Fig. 61. The slip-ways are strongly deformed after two months of use. The damage was caused by a rough surface from a too-cold mold, by molding compound temperature, and concentric cold-flow lines on the pinpoint gate, shown on the bottom right of the picture (see Fig. 63).

176

••Slip-way deformation, strong, ••Molding compound temperature is too low, ••Cold-flow lines on the pinpoint gate, ••Surface, rough, ••Mold temperature, too cold


LM Subchapter: Deformation/Delamination

Figure 63 ••Molding compound temperature is too low, ••Surface, rough, ••Orange skin

Slip way Figure 63, PA6.6 cover hinge (damaged part, M = 9, AL), part 1 from Fig. 61, a counterpart to part 2 in Fig. 62. The counterpart has a badly molded, rough surface. This was mainly due to lower molding compound temperature with orange skin (see Figs. 61 and 62).

Figures & Text

Figure 64 ••Delamination, ••Processing parameters, cold

Figure 64, PE headrest stiffener (M = 20, AL). The injection-molded part has a delaminated surface. The delamination was bent with a scalpel (arrows) for a better representation. The causes of damage were extremely cold processing parameters (see also → delamination and → processing parameters).

177


LM Subchapter: Delamination/Diffusion layer

Figure 65 ••Wetting agent test with toluene/n-propanol 1 : 3, ••Residual stresses, high, ••Vacuum methods, ••Vibration friction welding

Figure 65, PC roof window pane, vibration welded (M = 18, AL). The surface of the roof window, which was produced in the vacuum method, dissolved strip-like after 15 min of exposure in toluene/n-propanol 1 : 3 through molded part stresses. Cause of damage is a slightly too-low forming temperature, at the lower limit of the thermoelastic range. Thus high residual stresses developed during stretching of the PC board.

Figure 66

Figures & Text

••Oxygen barrier layer (antidiffusion layer), ••Laminating, ••Microscopy contrast with incorrect DIC slider

Figure 66, VPE heating pipe with oxygen barrier layer (M = 50, DL and wrong DIC slider + -plate). A 10 µm thin section of the pipe cross-section shows the layer structure from the inside to the outside: VPE pipe, 100 µm, and 200 µm oxygen barrier layers (usually made of vinyl alcohol VA). The coloring and the good color contrast are caused by an unusual combination of transmitted light DL and with a DIC lens cover for 100-fold rather than 50-fold magnification and a lambda plate.

178


LM Subchapter: Thin section

Figure 67 ••Thin section placement in Canada balsam

Figure 67, PE thin section (M = 6, DL), 10 µm thin section. It shows a thin section placement in Canada balsam on a glass slide with two dissecting needles. The sample is clamped in a microtome, and its surface is precut with 30 µm blank cuts so that the subsequent thin section covers the entire sample length and width. This happens again before the valid thin section, but in thin section thickness (10 µm are common). Then, a thin layer of Canada balsam is applied to the cleaned slide, usually with a dissecting needle in thin section size. The valid thin section should then be carefully pulled off with tweezers, a little faster than average speed, and should then be placed very carefully on the slide so that no pressure points in the thin section can lead to misinterpretations in the subsequent microscopic examination (see Figs. 68 to 71).


Figures & Text Figure 68, PE thin section (M = 6, DL), 10 µm thin section, continued from Fig. 67. The thin section is now carefully placed on the slide, covered with Canada balsam, and then covered with a cleaned glass cover. The glass cover should be pressed in at an angle using a pressure stamp so that no air bubbles are included. It flushes the air bubbles on the top edge of the glass in the Canada balsam flow front (see Figs. 67 to 71).

179




Figure 69, PE thin section (M = 6, DL), 10 µm thin section, continuation of Fig. 68. The glass cover is pressed on at an angle using a pressure stamp, and the disturbed air bubbles migrate to the flow front of the cover slip edge. It is recommended to not use too much Canada balsam; otherwise, the thin section can slip, float, or curl under the pressure stamp. Rough handling often results in preparation errors, which may result in wrong conclusions in the microscopic examination. Basically, a thin section and subsequent cut is done on a sample to avoid preparation errors. If the subsequent cut shows the same events as the first cut, they are real. Somewhat more problematic are very small abnormalities in the thin section thickness, as they will no longer be found in the subsequent cut due to their size. Then multiple subsequent cuts are done for control purposes (see Figs. 67 to 71).

Figure 70

Figures & Text

••Thin cutting error, eruptions, scratches, and nicks

Figure 70, PE thin section (M = 15, DL), continuation to Fig. 69. The 10 µm thin section has torn areas, a wave formation and ridges, and a greater section thickness in the gate (dark area, left). Causes are a dull microtome knife (generates wave formation) with notches (produces grooves) and outbreaks (causes torn areas). As a remedy, the microtome knife should be displaced laterally in the guide, up to a still intact, sharp point. A clean thin section can be done with the new sharp microtome knife area (see Figs. 67 to 71).

180



Figure 71 ••Thin section error, ••Control examination with incident light, ••Masterbatch coloring, ••Wave formation

Figure 71, PE thin section (M = 15, DL). Another 10 µm thin section that shows pigment streaks (carbon black), bright streaks (uncolored areas), and wave formation. Caution: the strikingly large, dark spot is not carbon black conglomerate, as may be expected, but an opaque, protracted piece of cleaning paper, which is hanging at the preparation needle. Without control of the microscope with incident light (IL), it would have gone unnoticed. Novices tend to scrape off the excess Canada balsam on the paper with a dissecting needle, but this is not recommended because of the risk of misinterpretation. The streaks developed through subsequent coloring with a masterbatch associated with a poor homogenization and wave formation caused a dull knife point. Residual stress, which is released during cutting, can also cause a similar wave formation (see also Figs. 67 to 70).

Figure 72 ••Thin section error with air intake, ••Molded part stresses

Figures & Text Figure 72, PBT thin section (M = 20, DL). The 20 µm thin section bulged due to high molded part stresses and pressed against the glass cover. This air was drawn from the glass cover edge under the glass cover. Other causes for such errors can be a rough thin section placement and too much applied or aged Canada balsam (see also → Canada balsam).

181


LM Subchapter: Embedding

Figure 73 ••Embedded in epoxy resin, ••Thin section 8 µm

Figure 73, PE film weld line (M = 8, DL-POL). The sample is embedded in epoxy resin EP for an 8 µm thin section (Fig. 74) because it cannot be clamped directly into the two clamping jaws of the microtome (see also → microtome).

Figure 74

Figures & Text

••Weld line is wider than the sum of the individual films, ••Thin section 8 µm, ••Thin section grooves, ••Heating element weld line, ••Adhesive strip method, ••Weld line thickening, ••Stresses through stretching

Figure 74, PE film weld line (M = 8, DL-POL). After being embedded in epoxy resin EP, an 8 µm thin section was performed with the adhesive strip method. The seam thickness of 475 µm is about three times thicker than the sum of the individual films, so a weld line with welding consumables (extra welding material) can be assumed. In fact, there is a common heating element weld line. The seam thickening occurs in the weld line through shrinkage of the multiaxial stretched blown film. The form-giving stresses, which are frozen in film blowing in the thermoelastic range, are released when heated, and the film will return to its original thickness. It is important in the preparation that the thin section grooves are always diagonal to the event (weld line layers) so that they cannot imitate a seam or layer. The adhesive strip method helps to fix strongly curled thin sections. The adhesive of the adhesive strip may, in the polarized transmitted light, imitate discolorations (isochromatics) and therefore not existing macromolecule orientations (see Fig. 73, → adhesive strip method).

182



Figure 75 ••Embedding in epoxy resin (PA/PTFE), ••Embedding when plane-parallel edges are missing

Figure 75, PA/PTFE piston ring (M = 10, AL). The sample was embedded in epoxy resin EP for a 10 µm thin section (Fig. 76) because it had no plane-parallel edges and therefore was not directly clamped between the parallel clamping jaws of the microtome. To improve the sliding properties, 18% of PTFE particles were added to the PA molding compound.

Figure 76

Figures & Text

••Embedded in epoxy resin, ••Thin section 10 µm, ••Holding pressure, ineffective, ••Pinpoint gate, frozen, ••Marginal zone, poor in spherulites, ••Vacuoles

Figure 76, PA/PTFE piston ring (M = 10, DL-POL), continuation to Fig. 75. After sanding two parallel edges, a 10 µm thin section was manufactured from the sample and embedded in epoxy resin EP (Fig. 75). Vacuoles and marginal zones, which are poor in spherulites, are visible under the microscope. Presumably, the pinpoint gate is frozen and the holding pressure was not effective anymore or was dropped too early (see also → holding pressure, → marginal zone, poor in spherulites, and → vacuoles).

183



Figure 77 ••Embedded in epoxy resin, ••Thin section 10 µm, ••Fracture, brittle fracture PA, ••Shaping, too late, ••Isochromatics, ••Homogenization, ••Internal stresses, ••Notches, ••Pigment streaks

Figure 77, PA electric cable duct (M = 15, DL-POL + -plate), with brittle fracture. The sample was embedded in epoxy resin EP for a 10 µm thin section (Fig. 76) because it was not directly clamped between the clamping parallel jaws of the microtome. The thin section shows the following as fracture causes: pigment streaks due to poor homogenization and notches in the corrugated pipe interior due to a too-late shaping in the corrugated pipe mold immediately after the extrusion. The problems caused by the thin-section cutting forces are negligible because they are a result of the sample supported by being embedded in epoxy resin, so the isochromatics also indicate high residual stresses (see also → internal stresses, → embedding, → extrusion, → homogenization, → isochromatics, and → microtome).

Figure 78

Figures & Text

••Granulate examination after embedding in epoxy resin

Figure 78, HDPE granulate (M = 12, AL). To examine a charge with suspected granulate contamination, some selected granulates were embedded in epoxy resin EP. After sanding two parallel-plane edges, a 10 µm thin section was manufactured from the embedded sample and microscopically examined (see also → granulate examination).

184


LM Subchapter: Coloring/Discharge

Figure 79 ••Coloring with alcohol-acetone mixture 1 : 1 and 3% fuchsine, ••Polished sample, ••Carbon black or titanium dioxide? ••Sanding instead of cutting, ••Weld lines, ••Weld line width, ••Examine titanium dioxide in incident light

Figure 79, PVC weld line, acrylic modified (M = 22, AL-DIC) of a window profile with 5% titanium dioxide. For the examination of the heating area of a heating element line, a polished sample was manufactured and stained with fuchsine for 5 min at 50 °C in an alcohol-acetone mixture 1 : 1 with 3% fuschsine. Thus, the weld lines were plastically visible. The spread of the heating zone with weld lines extended over (approximately) three times the wall thickness. With titanium dioxide content (white pigment) of 5%, a 10 µm thin section becomes opaque in transmitted light, black because of the high absorption of light. Therefore, a thin section should always be examined in incident light when (for example carbon black streaks) a thin section appears to contain black pigments. In incident light, the supposedly black pigments suddenly show their proper white color (see also → coloring, → fuchsine, → contrast types, and → polished sample).

Figure 80

Figures & Text

••Voltage flashovers at 20,000 to 40,000 volts in PP, ••Creeping current impression, ••Static electricity, ••Voltage breakdown

Figure 80, PP membrane (M = 12, AL). A slurry of olives is, for example, pressed between 2.50 m2 PP membranes. It often causes high voltages in the range of 20,000 to 40,000 volts due to static electricity in the used plastic polypropylene PP. These voltages are spontaneously discharged in voltage breakdowns and voltage flashovers where they damage the PP membrane or may even perforate it. Such a voltage breakdown is shown in the figure at the press-knob foot with a brown creeping current impression.

185


LM Subchapter: Discharge/Extrusion

Figure 81

Pipe wall

••Perforation, ••Static electricity high, at the pipe intake, ••Voltage breakdown with “needle tract,” ••Stab injury?

Figure 81, PE gas pipe, extruded (M = 15, Al), with an alleged stab injury (“needle tract”). A mysterious, black-brown perforation with approximately 800 µm diameter was found in the pipe wall in a microscopic examination of the leaking gas pipe. The noncircular perforation had longitudinal grooves and a conical depression at the edge of the hole, which is the entry point (arrow). A stab injury by a nail or the like was ruled out because the “needle tract,” which is well below 750 µm long, was conically curved, and SEM images showed a knob-shaped, brown-black interior surface with longitudinal folds. The perforation and leakage of the gas pipe is probably a voltage breakdown due to high static electricity during the pipe installation from the roll in the installation chute. Very high electric voltages can develop in times of drought, depending on the weather and soil moisture.

Figure 82

Figures & Text

••Molding compound temperature, too low ••Seam intake, V-shaped, ••Shear joint, ••Stretched area, cold

Figure 82, PE diesel can (M = 6, Al). A diesel canister, which is produced by injection blow molding, has a shear joint in the bottom area. The double V-shaped seam intake and the cold stretched area (arrows) in the bottom outside developed due to a too-low molding compound temperature (see Fig. 83 and → injection blow molding).

186


LM Subchapter: Extrusion

Figure 83 ••Shear joint with V-shaped seam intake and notch effect

Figure 83, PE diesel can (M = 50, DL-POL), detail from Fig. 82. A 10 µm thin section through the shear joint outside of the bottom edge shows an extreme, V-shaped seam intake with a double seam base. Cause of damage was a too-cold molding compound temperature. The partially welded seam broke due to expansion of the diesel fuel at higher temperatures outdoors. The notch effect in the double seam also had a favorable effect (see also → molding compound temperature, too cold).

Figure 84

Figures & Text

••Defect in a corrugated pipe embossing, ••Molding compound temperature, low, ••Shear joint in the mold separation

Figure 84, PE corrugated pipe DN 200 (M = 10, AL). During extrusion with subsequent embossing of the corrugated pipe, an undesirably shear joint formed in the mold separation due to a too-low processing temperature in the mold. This imperfection has been leaking in the subsequent use. In a telephone conversation, the customer confirmed that the molding compound temperature was too low.

187


LM Subchapter: Extrusion/Films

Figure 85 ••Blown film, coextruded, ••Extrusion blow molding, ••Heating element wall thickness, ••Shrinking during welding, ••Weld line thickness is greater than the sum of the individual films, ••Scalpel cut shows film layers

Figure 85, PE carry bag, noble (M = 8, AL). A scalpel cut through the heating element weld line in the carry bag bottom in the stereomicroscope shows a weld line thickness that is greater than the sum of the two film thicknesses. The welded film is a multiaxial stretched, coextruded blown film and consists of two outer layers with a white intermediate film. The cause for the abnormal weld line thickness is shrinking of the multiaxially stretched blown film due to the heat of hot heating element welding.

Figure 86

Figures & Text

••Extrusion blow molding, ••Foreign particles (globule), ••Globule in the multilayer film, ••Plastic particles, cannot be melted?, ••Multilayer film with globule

Figure 86, PE multilayer film (three-layer film, M = 10, DL-POL). The microscopic examination shows a globule as a tactile, spherical film thickening between the film layers. This developed due to a foreign particle or hard-to-melt or nonmelting plastic particles (see Fig. 87 and → foreign particles).

188


LM Subchapter: Films

Figure 87 ••Extrusion blow molding, ••Multilayer film with globule

Figure 87, PE multilayer film (three-layer film, M = 33, DL-POL), detail enlargement from Fig. 86. The microscopic examination shows a globule as a tactile, spherical film thickening between the film layers.

Figure 88

Figures & Text

••Extrusion blow molding, ••Multilayer film with a hole, ••Three layers of film

Figure 88, PE multilayer film (three-layer film, M = 10, DL-POL), detail enlargement from Fig. 87. The microscopic examination shows a hole with a lateral crack in the intermediate film between the two intact layers.

189



Figure 89 ••Extrusion blow molding, ••Multilayer film with layer fracture, ••Three film layers, ••Melt fracture in multilayer film, ••Specks or drafts?

Figure 89, PE multilayer film (three-layer film, M = 100, DL-POL), detail enlargement from Fig. 88. The microscopic examination shows a hole-like melt fracture with a lateral crack initiation in the intermediate film between the two intact film layers. The cause was a layer fracture by draft or a speck in the multiaxial expansion (stretching) of the film pipe during blowing (see Fig. 90 and → specks).

Figure 90

Figures & Text

••Extrusion blow molding, ••Multilayer film with melt fracture caused by drafts, ••Three layers of film

Figure 90, PE multilayer film (three-layer film, M = 50, DL-POL) detail from another area of the multilayer film in Fig. 89. The microscopic examination also shows a hole-like melt fracture in the top film top layer. The intermediate film layer and a rear film top layer are not affected. The cause was a layer fracture in the inflation range due to poor temperature control (draft).

190



Figure 91 ••Extrusion blow molding, ••Three-layer film, ••Flow obstruction in the extruder blow head, ••Molding compound particle, burnt, ••Multilayer film with burnt streaks

Figure 91, PE multilayer film (three-layer film, M = 100, DL-POL). The microscopic examination shows burnt streaks in the intermediate film between two film layers. The damage was caused by a burnt molding compound particle by a too-long dwell time and flow hindrance in the extruder or extruder blow head.

Figure 92 ••Extrusion blow molding, ••Single-layer film, ••Film scratches in the single layer film

Figures & Text Figure 92, PE single layer film (M = 20, DL-POL). The microscopic examination shows a film scratch in the surface of the film. The cause of the mechanical damage was probably a contaminant in the winding or unwinding of the film or in use.

191



Figure 93 ••Extrusion blow molding, ••Single layer with intentional film scratches

Figure 93, PE single layer film (M = 50, AL + low DL-POL). The microscopic examination shows an intentional film scratch with combined incident light and low polarized transmitted light. The deliberate film damage was done by hand with a dull plastic dissecting needle, as it is used for the application of Canada balsam.

Figure 94

Figures & Text

••Extrusion blow molding, ••The multilayer film with film fold, ••Slip-stick effect

Figure 94, PE-multilayer film (M = 50, DL-POL). The microscopic examination shows an elongated film fold. The damage was caused by a relative movement (delay) between the film layers close to the blow head by a slip-stick effect at higher temperature in the transition from thermoplastic (see also → slip-stick effect) into the thermoelastic range.

192



Figure 95 ••Extrusion blow molding, ••Melting range, wider, ••Film conglomerate, difficult to melt or crosslinked, ••Film specks

Figure 95, PE film (M = 100, DL + low AL). The microscopic examination shows an elongated film speck in an extrusion-blown PE film. A speck is a highly molecular, hard-to-melt, or crosslinked film particle (in this figure, polyethylene PE) with a poor distribution of macromolecule lengths. The cause was mostly a too-wide melting range of the molding compound (Gauss curve) or a foreign material.

Figure 96 ••Clamping block method with scalpel-cut is a fast and accurate method for the examination of film layer thicknesses

PVC piece

Figures & Text

Film

Figure 96, PVC clamping block (M = 1 : 1). The clamping block method is much faster and better for the examination of the layer thickness of multilayer films than an embedding in epoxy resin EP and even better than a thin section. An approximately equal-sized film blank is inserted in both clamping halves of the PVC clamping blocks, so that both clamping block halves are tightened at the same time with the two brass screws. The excess film is then cut off with a scalpel (pulling diagonally and flush with the surface of the clamping blocks). Thereby, the resulting cut grooves pass diagonally to the individual layers and do not simulate more layers than are present. A preparation with the clamping block method or a block section (sample residual in the microtome) shows the exact layer thicknesses during the examination. However, a thin section only shows the layers and their type but not true sizes because they are distorted by compressing and transverse contraction during cutting. The thin section is unfortunately still recommended in the literature (see also Fig. 97).

193



Figure 97 ••Extrusion blow molding, ••Multilayer film with seven layers, ••Block ground sample instead of scalpel cut, ••IR and DSC analyses

Figure 97, PE/PA6/PP/PE multilayer film with seven layers (M = 500, AL-DIC). Hygienic packaging (for sanitary towels) consists, for example, of four extrusion-blown films with a film layer sequence from top to bottom of PE/PA6/PP/PE and three adhesive layers for a total thickness of 20 µm. The microscopic analysis of the film thickness and film layers was done with the clamping block method by grinding. The best result was with 1200 wet sandpaper because the film layers were smeared by each other due to heat that developed during post-polishing. Faster and easier to carry out would have been a scalpel cut like in Fig. 96. The film layers were isolated and their type of plastic was determined using IR and DSC analyses after the determination of the layer thicknesses.

Figures & Text

Figure 98 Paint residue

••Extrusion blow molding, ••Paint delamination from the cover film, ••Multilayer film with six film and five adhesive layers, ••Top secret examinations

Figure 98, Paint delamination on a multilayer film (M = 50, DL, with low polarization POL + -plate). The microscopic examination of the multilayer film was performed on a 10 µm thin section. It has six film layers, five adhesive layers, and dull spots in many areas of the surface. The client wanted to know the cause, but did not give any information about the quality of the paint, the primer, the film types, and processing of this new development. Many paint layer areas detached from the cover film, as microscopically visible in the presence of the customer. These detachments were the cause of the dull spots. According to our expectation, the paint embrittled through a drop-like media attack, and the paint adhesion is not optimal. The film thicknesses and its types of plastic could not be examined. Therefore, no further recommendations were possible. Our observations on the present damage, along with some immediately taken digital images, were enough for the client, who then left us with all their samples.

194


LM Subchapter: Mass inversion

Figure 99 ••Injecting, too fast, ••Reversal of the flow front, ••Free-jet formation, ••Mass inversion, ••Large and small spherulites, ••Notch effect, ••Turbulent filling, ••Tooth fracture through pigment streaks

Figure 99, PC saw tooth thread (M = 15, DL-POL + -plate), 10 µm thin section. The saw tooth broke off at a stress while in use, along the dark pigment steak. Damage causes were a mass inversion (reversal of the flow front), dark pigment streaks, and a notch on the bottom rack. A mass inversion occurs, for example, when molding compound “bonds” with the back-flowing molding compound from the mold end at a high injection rate. This happens, for example, in a turbulent filling and free-jet formation when various rapid mass flows of equal or opposite direction meet each other in the mold (see also → mass inversion).

Figure 100

Figures & Text

••Reversal of the flow front, ••Mass inversion, ••Notch effect, ••Layer formation, ••Large and small spherulites, ••Spherulite streaks, ••Mold filling, oscillating

Figure 100, PA6 handle (damaged part, M = 30, DL-POL + -plate), 10 µm thin section with a mass inversion. A mass inversion developed in a mixture of the same or opposing mass flows (layer mixture) with different temperatures. Large spherulite streaks grew in the semi crystalline plastics in the warmer layers and smaller ones grew in the colder layers. A mechanical stress caused a fracture in the spherulite streaks through a notch effect in the transition from the large to the small spherulites. Causes are usually a too-rapid injection or an oscillating mold filling, where cold mass flows (layers) from the cooled edge areas mix with the interior of the warm molded part.

195


LM Subchapter: Mass inversion

Figure 101 cool

••Mass inversion ••Large and small spherulites, ••Homogenization, poor, ••Notch effect, ••Hot-cold streaks

warm

Figure 101, PA molding compound (M = 100, DL-POL + -plate) with a hot-cold mixture (mixing spherulites). The mixture of warm and already cooled molding compound developed large spherulites in a small-spherulitic matrix. At a mechanical stress, cracks can develop through the notch effect between the large and small spherulites. Cause of this mass inversion was an intermittent injection with mixing of warm interior with cool exterior molding compound. However, injected hot-cold streaks can show such an error through insufficient homogenization. Hot-cold mixtures can occur during injection molding and extrusion.

Figures & Text

Figure 102 ••Mass inversion, ••Microcracks, very fine, ••Layer formation, ••Layer flows, multilayer, ••Mold filling, turbulent

Figure 102, PS panel damaged part (M = 25, DL). A 10 µm thin section through the broken panel shows an inhomogeneous molding compound with multilayered form, opposing mass flows (mass inversion), and very fine microcracks (bottom right corner of picture). The damage developed through too-rapid injection (turbulent mold filling). The fine microcracks are a preparation error, because the thin section was treated roughly during fixation with Canada balsam onto the slide.

196


LM Subchapters: Equipment

Figure 103 ••Preparation equipment for thin section placement

Figure 103, Preparation equipment from left to right: marker (red, water resistant), compression die for glass cover, Canada balsam, glass covers (above), slide (below), PVC dissecting needle, tweezers, steel preparation needle, and a scalpel.

Figures & Text

Figure 104 ••Universal microscope with: ••Aperture, ••Condenser, ••Field diaphragm, ••Objective revolver, ••Polarizer, ••Sample stage

Figure 104, Universal microscope (M = 1 : 1), transmitted light field with aperture (5), condenser (in 5), field diaphragm (7), objective revolver (1), polarizer (6), and sample stage (2).

197


LM Subchapter: Equipment

Figure 105 ••Universal microscope with: ••Dark-bright field slider, ••Focusing ring for diopter alignment, ••Camera switch, ••Conversion filters, ••Field diaphragm for incident light, ••Objective revolver, ••Polarizer, ••Sample stage

Figure 105, Universal microscope (photo), incident and transmitted light field with dark-bright field slider (3), camera switch (5), conversion filter (7), field diaphragm for incident light (6), objective revolver (1), polarizer (4), and sample stage (2). The two eyepieces (top left of the figure) have focusing rings for diopter alignment for defective vision of the eye.

Figure 106

Figures & Text

••Universal microscope with: ••Aperture in incident light, ••Incident light illuminator, ••Transmitted light illuminator, ••Field diaphragm for incident light

Figure 106, Universal microscope (photo), incident light field with aperture (7) in incident light, incident light illuminator (9), transmitted light illuminator (10), and field diaphragm for incident light (6).

198



Figure 107 ••Universal microscope with: ••Aperture, ••Rotary knob for sample focusing, ••Field lens, folded out, ••Condenser-height adjustment, ••Field diaphragm, ••Polarizer, ••Sample stage-height fixation, ••Centering screws for the light field diaphragm

Figure 107, Universal microscope (M = 1 : 1), transmitted light field with aperture (5), rotary knob for sample focusing (3), field lens, folded out (11), condenser height adjustment for Köhler illumination (12), light field diaphragm (7), polarizer (6), sample stage-height fixation (13), and centering screws for the field diaphragm (14).

Figure 108 Lifting method

••Lifting method for thin sections, ••Adhesive strip method

Thin sections Tweezers

Tweezer method: Remove thin sections with tweezers (Lifting speed = cutting speed)

Adhesive strip Adhesive strip end Sample 2

Adhesive strip method: adhesive strip end turn-around and remove thin section with tweezers

Canada balsam Glass cover Sample 3

Glass cover strip method: adhesive strip end turn-around and remove thin section with tweezers

Figure 108, Lifting method for thin section cutting. There are a total of three lifting methods for processing thin sections. Lifting method A is usually used for normally cuttable plastics, and lifting method B for very sensitive, for fast-tearing plastics. Beforehand, a transparent adhesive tape is applied (free of bubbles) to the thin section to be cut, and the overturned adhesive strip end is held with tweezers. The resulting thin section is slowly removed, correlating with the cutting speed. The lifting method C was mentioned for completeness, but it has no practical significance.

199

Figures & Text

Sample 1



Figure 109 ••Microtome (schematic), ••Thin-cutting device (schematic) for thin section production, ••Vertical microtome

Figure 109, Vertical microtome (schematic) for thin section production. Thin sections can be produced in minutes when they do not contain abrasive (dulling) fillers or reinforcing materials (glass fibers, glass pellets, or glass flakes). Some samples cannot be cut in any case because they fray or soften, such as soft PVC, polyurethane rigid foams, elastomers, and various PMMA injection-molding types. But PVC integral foams (for example, KG pipes with PVC rigid foam between the inner and outer layer) can be better cut than sanded (see also → block section, instead of polished sample). The thin section of all examination options gives the fastest comprehensive response to the inner quality or structural damage of a molded part and information for processing, damage cause, and elimination. During infrared spectroscopy or differential thermal analysis, only the total crystallinity should be captured. It should only show a thin section, the location and size of the crystallinity, as spherulites between the plastic core (middle panel) and the marginal zone, which is poor in spherulites (see also → block section).

Figure 110

Figures & Text

••Thin grinding device to manufacture thin ground samples

Figure 110, A thin ground sample is produced mechanically by abrasion within a thin grinding device. The sample is fixed to a vacuum holder and ground in 5 to 10 µm increments. Epoxy resin is usually used as an embedding agent. A cyanoacrylate is used for gluing (soluble in water), but it is better to use a diffusion adhesive based on acrylic. After reaching the final thickness of 20 µm (as an example), the diffusion adhesive can be carefully removed from the glass slide with a dissecting needle after a 10 minute immersion in ethanol. Most plastics are sufficiently resistant. Then the exposed thin ground sample is fixed to the glass slide with Canada balsam or Eukitt EK and is then covered with a glass cover. In this way, clean thin ground samples without air bubbles, peeling areas, and coolant-back movement can be produced. A thin ground sample is a 5 to 50 µm thinly ground, mostly abrasive sample for a microscopic examination of filler and reinforcing materials. The event thickness determines the sample thickness in the production.

200


LM Subchapter: Glass fibers

Figure 111 ••Glass fiber length determination in a good part, ••Dissolution in acetone, ••Glass fibers, long

Figure 111, PA6.6 molded part, good part (M = 31, DL) after dissolving the PA6.6 matrix in acetone. The glass fibers were suspended in a Petri dish and photographed, and the fiber lengths and their distribution are identified with software for digital image analysis. Since the average fiber length is 995 µm, the breaking resistance is higher than in the fractured damaged part (Fig. 112).

Figure 112

Figures & Text

••Glass fiber length determination for a damaged part, ••Dissolution in acetone, ••Glass fibers, short

Figure 112, PA6.6 molded part, damaged part (M = 31, DL) after dissolving the PA6.6 matrix in acetone. The glass fibers were also suspended in a Petri dish, photographed, and measured with software for digital image analysis. The average glass fiber length is only 278 µm, so the breaking resistance is also significantly lower (see also Fig. 111).

201



Figure 113 Cracking area

••Glass fibers, unfavorably positioned, ••Glass fibers obstruct the holding pressure effect, ••Microvacuoles

Widening force

Figure 113, PA-GF25 pulley (M = 20, AL). A polished sample through the glass fiber reinforced pulley shows glass fibers, which are unfavorable, located in the stress direction, and microvacuoles, which weaken the cross-section. The risk of microvacuoles particularly increases with increasing fiber filling especially at low processing temperatures. The holding pressure can then no longer press through enough molding compound as shrinkage compensation, because of the increase in flow resistance due to the glass fibers (see also → holding pressure error).

Figure 114

Figures & Text

••Glass fiber breakage, ••Glass fibers, highly oriented, ••Contrast enhancement with an almost-closed aperture

Figure 114, POM-GF30 aperture (M = 100, DL-POL), 20 µm thin ground sample. The examination was done in transmitted light at low polarization and with an almost-closed aperture to increase the contrast. The highly oriented glass fibers in the direction of flow of the molding compound are sometimes strongly fractured.

202



Figure 115 ••Glass fiber breakage, ••Glass fiber orientation, ••Contrast enhancement through contrast mixture, ••Polarization, weak, ••Wollaston prism (DIC slider)

Figure 115, PA6.6-GF30 aperture (M = 100, DL-POL + DIC), 20 µm thin ground sample. The examination was done at low polarization in transmitted light with a Wollaston prism (DIC slider) and a small closed aperture. The unusual mixture of contrasting methods improved the contrast. Partially strongly broken, highly oriented glass fibers in the flow direction of the molding compound can be seen in the picture (see also → contrast method).

Figure 116

Figures & Text

••Flow shadow ••Flow resistance, high, ••Molded part resistance, reduced, ••Glass fiber accumulation and glass fiber segregation, ••Plastic binding missing, ••Flow division

Figure 116, PC-GF35 molded part (M = 30, DL-POL), 30 µm thin ground sample. The gating is done on the right-hand side. An accumulation of glass fiber forms in the web (arrow 1) in the flow shadow of the flow divider. There, more fibers without plastic bonds were deposited. Glass fibers without plastic bonds weaken the molded part strength. The partial glass fiber accumulation caused glass fiber segregation in the following areas, which also reduced the molded part strength. Fracture was caused by the glass fiber enrichment (arrow 1) and the notch (arrow 2). Glass fiber accumulations develop in the flow shadow of flow divisions and thus glass fiber segregations in those molded part areas. But also high flow resistances to flow in, for example, narrow, long, and rough cross-sections as well as high injection rates, low molding compounds, or mold temperatures can cause glass fiber segregations.

203



Figure 117 ••Moisture absorption, ••Media influence, ••Migration of pigments, ••Pigment conglomerates

Figure 117, PA6.6-GF30 refrigerator handle (M = 200, DL). A 20 µm thin section of the refrigerator handle shows fiberglass and pigment conglomerates by subsequent inhomogeneous coloring with red pigment powder. PA6.6 can accommodate up to 4% moisture and release it again. As the microscopic examination showed, due to media influences like hand sweat, deodorant, and humidity, near-surface pigment conglomerates were partially washed out and led to an undesirable reddish surface staining.

Figure 118

Figures & Text

••Carbon fibers and glass fibers

Figure 118, PA6-GF20 fan blade (M = 100, DL). A 10 µm thin section within the hub-center of the wall has predominantly longitudinally oriented, black carbon fibers in the image plane and light glass fibers.

204



Figure 119 ••Block ground sample, ••Extensional flow, ••Molded part design is affected, ••Glass fiber orientation, ••Orientation, ••Shear flow, ••Core, plastic (wall center)

Figure 119, POM-GF30 molded part (M = 25, AL), block ground sample made by hand through a broken web. In the plastic core (wall center, the longest and highest temperature range), the glass fibers are predominantly oriented perpendicular to the image plane due to extensional flow, and in the two boundary layers, due to a shear flow mainly in the direction of flow of the molding compound. A block ground sample can be manufactured considerably faster than a thin ground sample. Ideal would be a uniform glass fiber orientation so that all glass fibers lie in the direction of the force and are subjected to tensile stress. But this is, in a good approximation, only possible in linear molded parts and decreases with increasing complexity of the molded part (see also → block ground sample).

Figure 120

Figures & Text

••Fracture, intentional, ••Lack of holding pressure, partial, ••Vacuoles and glass fibers

Figure 120, PBT strainer (M = 20, AL), a damaged part with 48% glass fibers. Vacuoles (arrows) are seen in many glass fibers in the marginal zone after an intentionally generated fracture. The cross-section weakening vacuoles prove a partial holding pressure. This is additionally favored by high glass fiber content because the molding composition can flow poorly into the mold. Therefore, the holding pressure should be high enough and should act long enough to adjust the molding compound (shrinkage compensation) (see also → lack of holding pressure).

205



Figure 121 ••Microvacuoles in the weld line area, ••Microvacuoles due to a high glass fiber content

Glass fibers

Vacuoles

Figure 121, PBT strainer (M = 31, AL), damaged part, detail from Fig. 120 with 48% glass fibers. Many microvacuoles (red arrows) and diffusely distributed glass fibers (blue arrow) can be found In the intentionally fractured web, in the weld area between two pinpoint gates. The high glass fiber filling favored the formation of the microvacuoles due to a reduced flowability of the molding compound. The originally intended improvement in strength through a high glass fiber content worsens due to the formation of microvacuoles. It is therefore recommended to find a compromise between the glass fiber content and the molded part strength as well as the wear of the machine and the mold (see also → weld line and → microvacuoles).

Figure 122

Figures & Text

••Glass fibers protrude through the surface, ••Holding pressure and mold temperature, too low

Figure 122, PC surface (M = 31, AL), damaged part. The molded part surface seems porous and glass fibers protrude. Causes are a cold mold temperature (possibly also molding compound temperature) and too-low holding pressure. Thus, the glass fibers were not well enough incorporated into the surface, which is not completely closed. Such an error causes a surface pollution that is difficult to clean and would favor creeping currents in electrical equipment (see also → holding pressure error).

206


LM Subchapter: Granulate

Figure 123 ••Residual granulate with flow lines, ••Matrix welding, poor

Figure 123, PETP housing (M = 20, DL-POL + -plate), 10 µm thin section in polarized transmitted light with -plate. The unmelted 3.10 mm residual granulate in the housing wall center with flow lines acts to reduce strength because its margins are not optimally “welded” with the matrix.

Figure 124

Figures & Text

••Crowning through unmelted granulate, ••Molding compound temperature, too low, foreign granulate, hard to melt, ••Homogenization, poor

Figure 124, PP container (M = 8, AL), polished sample with unmelted granulate. The wall thickness is embossed. The cause of damage was either a foreign granulate, which is hard to melt, or a too-short, poor homogenization with a low molding compound temperature. These large, unmelted granulate residues get into the molded part but only with a large gate (direct gate). These results were enough for the client. Therefore, there were no further examinations (see also → granulate, unmelted and → homogenization).

207



Figure 125 ••Illumination angle is important, ••Foreign granules, ••Gloss reflection simulates metal, ••Solvent trial, ••Confusion with metal abrasion

Figures & Text

Figure 125, ABS/PC sheet, polymer blend (M = 31, AL). The surface fractured shell-like above a foreign granulate. Because of its metallic appearance, metal abrasion (metal particles) of the screw or cylinder armor was suspected. A detailed microscopic examination and solvent experiments revealed that instead of a metal, a black foreign granulate was present. The metallic appearance of the black foreign granulate was a gloss reflection. Therefore, different illumination angles in the microscopic examination or dark field reflection process AL-DL should be chosen to always rule out confusion with metal particles. Isolated particles could also be examined for metal with melting trials or magnets.

Figure 126 ••Granulate residue unmelted, ••Hole or amorphous particle?, ••Confusion with carbon conglomerate

Figure 126, PE-pipe cross-section with white particles (M = 200, DL-POL). The bright particles in the center of the image have a recognizable spherulite structure in polarized transmitted light and are therefore actually unmelted PE granulate residue and not ripped-out carbon black conglomerate (hole). Holes or amorphous particles are black in polarized DL-POL transmitted light.

208



Figure 127 ••Mixing, inhomogeneous, ••Throughput is too high, ••Coloring, subsequent, ••Perforated disc imprinting, ••Pigment streaks, bright

Figure 127, PE drinking water pipe, extruded, (M = 50, DL), 10 µm thin section with the impression of the perforated disc in the extruder head. The bright pigment streaks are uncolored molding compound. The cause was an inhomogeneous mixing of the molding compound in the extruder. This error always occurs at a subsequent coloration of the molding compound and gives information about a too-high throughput (also called flow rate; see also → perforated disc imprinting and → extrusion).

Figures & Text

Figure 128 ••Molding compound, primary colored, ••Molding compound temperature, too low, ••Homogenization, poor, ••Masterbatch coloring, subsequent, ••Residual granulate, unmelted with spherulite structure, ••Confusion with foreign particle

Residual granulate

Figure 128, PE heating element weld line (M = 100, DL), 10 µm thin section through an uncolored, unmelted residual granulate up to 300 µm in length. Cause was an insufficient homogenization at a too-low molding compound temperature. A subsequent examination in polarized transmitted light showed the common PE spherulite structures in the residual granulate. Furthermore, there was a subsequent coloring with masterbatch because a primary colored molding compound has no such pigment streaks.

209



Figure 129 ••Residual granulate, different colors, ••Residual granulate additive, different

Figure 129, PA6.6 furniture connector (damaged part, M = 8, AL), polished sample with different-colored, unmelted granulate residues. Such large granulate residuals are rare and only possible with a large direct gate. The different colors show the use of different regranulate contents with presumably different qualities in the melting behavior.

Figure 130

Figures & Text

••Fracture surface, polished, ••Molding compound, inhomogeneous, ••Granulate residuals in new product

Figure 130, PE sealing plugs (M = 6, AL), broken. A polished sample of the fracture surface of the injection-molded part shows an inhomogeneous molding compound with white, unmelted granulate residues (which act as gloss areas in the figure) in the entire cross-section. Cause of damage was white PE granulates in the delivered, new black PE product. The white PE granulates are probably residues from a previous delivery due to inadequate cleaning of the silo truck.

210



Figure 131 ••Granulate residuals, unmelted, ••Media attack (chemicals, UV)

Figure 131, CA housing (M = 12, AL). An unusally high amount of unmelted granulate residues are exposed in the molded part surface during the embrittlement of an injection-molded housing surface due to an unknown media attack (chemicals or UV). (see also → granulate, unmelted).

Figure 132 ••Granulate contamination, ••Pigment streaks, black

Figures & Text Figure 132, ABS granulate (M = 12, AL). The ABS housings for thermos flasks, which are manufactured from white, primary colored granulate in injection molding, had black pigment streaks. The pigment streaks were caused by black contaminations in the granulate, as a granulate examination showed. An examination of the granulate in pigment streaks is therefore recommended (see also → granulate examination and → pigment streaks).

211



Figure 133 ••Granulate contamination

Figure 133, TEEE vacuum line (M = 8, AL), granulate examination. The granulate, which was used for the manufacture of an extruded vacuum line, was examined under the microscope in delivery condition. The 100 g TEEE granulate is visually examined on a bright tablet, and six contaminated granulates with white inclusions are found. The 10 µm thin sections are manufactured from the contaminated granulate, and it could be demonstrated that the white inclusions were contaminants in polyethylene PE by an FTIR analysis. TEEE is a thermoplastics elastomer TPE based on sulfide-ether (see also Fig. 134, → FTIR analysis, and → granulate contamination).

Figure 134

Figures & Text

••Thin section waving, ••Coloring, subsequent, ••Perforated disc impression

Figure 134, TEEE vacuum line (M = 25, DL), damaged part. A 10 µm thin section through the supplied, extruded TEEE vacuum line shows inhomogeneous, uncolored areas in the impression of the perforated disc of the pipe wall and a thin section of waviness. Causes are the white polyethylene inclusions in the granulate (Fig. 133). The blame for the fracture of the vacuum line can be found with the raw material supplier, because the plastic inclusions acted to reduce strength. The thin section waviness probably developed from freed internal stresses, which were present in the extruded vacuum line (see also Fig. 133).

212



Figure 135 ••Fibrils, ••Granulate, unmelted, ••Homogenization, poor, ••Mass temperature, too low

Figure 135, PA sheet, extruded (M = 25, DL-POL + ). In the damage area, an unmelted granulate of about 2000 µm in length was found in a 10 µm thin section. Causes were internal molded part stresses, which dissolved the residual granulate from the matrix upon cooling and thereby formed fibrils, as well as a poor homogenization through a too-low molding compound temperature, and the resulting insufficient “welding” of the remaining granulate with the matrix.

Figure 136 ••Block ground sample, ••Fracture zone with residual granulate

Figures & Text Figure 136, PE pig rust (M = 8, AL), damaged part. A block ground sample through the fracture area shows unmelted granulates. The causes of damage for the fracture were accidental mixing in of a wrong PE batch, a subsequent coloring with masterbatch at a too-low molding compound temperature, and poor homogenization (see also → molding compound temperature, too cold and → homogenization).

213


LM Subchapter: Isochromatics

Figure 137 ••Photoelasticity, ••Filling study, ••Longitudinal orientation and transverse orientation of the macromolecules, ••Laminar filling, ••Longitudinal cracking

Figure 137, PE bottle (M = 1 : 1, DL-POL), damaged part with longitudinal cracking. The bottle shows (in the lower third) a horizontally extending isochromatic (colored lines of the same color) of a transverse flow of the molding compound during the filling process in the photoelasticity. It means that the original longitudinal orientation of the macromolecules with longitudinal cracking there transfers into a transverse orientation. This change is mainly caused by a reduced injection rate, a larger gate, and higher mold temperature (filling study recommended). The target for a multiaxial internal pressure resistance of the bottle would be a laminar filling, preferably with no apparent orientation of the molding material.

Figure 138

Figures & Text

••Flow fronts in the molding compound, ••Isochromatics in SAN

Figure 138, SAN cup, injection-molded part (M = 18, DL-POL). Colored lines as isochromatics and molding compound flow fronts become visible in polarized transmitted light in transparent and translucent molded parts (see also Fig. 139, → isochromatics, and → polarization optics).

214



Figure 139 ••Flow fronts in the molding compound, ••Isochromatics in SAN

Figure 139, SAN cup, injection-molded part (M = 18, DL-POL). The isochromatics and the flow front of the molding compound become visible in polarized transmitted light in a SAN cup. A molding compound flow front is formed in the shape in the mold due to the convergence of two or more mass flows and isochromatics through macromolecule orientation in stress ranges (see Fig. 138).

Figure 140

Figures & Text

••Weld line PE, visible in polarized transmitted light, ••Residual stresses, ••Molding compound flows, ••Macromolecule orientations

Figure 140, PE spray nozzle (M = 25, DL-POL) with isochromatics in polarized transmitted light. The isochromatics often make macromolecule orientations visible in the higher residual stresses and weld line. A weld line is unavoidably created in a core flowing, where separated mass flows meet again. The lower the temperature during the meeting, the more visible and worse the weld line. The example shows that a weld line with isochromatics becomes visible in polarized transmitted light, even with a translucent molding compound. To improve this situation, the mold temperature should be slightly raised and the molding compound temperature should be analyzed (see also Fig. 141, → molded part stresses, → core flowing, → contrast method, and → mold temperature).

215



Figure 141 ••Weld line in PE is not visible in normal transmitted light

Figure 141, PE spray nozzle (M = 25, DL). Weld lines and macromolecular orientations are not visible as in Fig. 140 in normal transmitted light.

Figure 142

Figures & Text

••Core flowing with isochromatics, ••Macromolecule orientations

Figure 142, SAN disc (M = 6, DL-POL). Many isochromatics can be seen on the core flowing (holes) under the microscope in polarized transmitted light. These color lines develop through a change in refraction in the range of macromolecule orientations, and these in turn develop in the mold filling through rheological flow processes or in stress areas during cooling.

216



Figure 143 ••Cold-flow area, wavy, ••Over-injection

Over-injection

Cold-flow area

Figure 143, PE gas pipe bushing (M = 20, AL) with a weld-line-like, wavy cold-flow area and an over-injection in the surface (see also → cold-flow area and → over-injection).

Figure 144 ••Gate area, ••Molding compound, cold ••Hot runner, ••Cold-flow areas, fine, ••Waves on the mold part

217

Figures & Text

Figure 144, PS vanity mirror housing (M = 18, AL + DL) with cold-flow areas and cold-flow lines in the gate area (arrow). Damage causation: Cooled molding compound flowed through a low-tempered hot runner in the holding pressure phase. It flowed with great difficulty into the mold cavity and produced finely waved, cold-flow areas, which are close to the gate at the cold mold surface (see also → molding compound, cold, → cold-flow areas, → holding pressure error, → lack of holding pressure, and → injection molding).



Figure 145 ••Flowability, reduced, ••Mold wetting, poor, ••Mold filling, poor

Figure 145, PE expander handle (damaged part, M = 25, AL) with poor mold filling (also mold wetting, blue arrow) and a cold-flow area (white arrow) due to a lower flowability in the too-cold mold. If a mold is too cold, the viscous molding compound cannot properly reach the end of the mold and fill fine cross-sections.

Figure 146

Figures & Text

••Flow viscosity (molding compound), ••Molding compound temperature too low, ••Pinpoint gate with cold-flow lines, ••Record grooves, ••Mold impression, poor, ••Mold temperature, too low

Figure 146, POM molded part (damaged part, M = 6, AL), pinpoint gate with cold-flow lines (arrow) and poor mold impression. Such concentric flow lines were and are still called “record grooves.” This was caused by a too-high flow viscosity of the molding compound, due to a too-low molding compound temperature because the cold-flow lines already developed at the gate. A too-low mold temperature also leads to such an error (see also → cold flow).

218



Figure 147 ••Gate with dome, ••Molding compound, cold, ••Cold-flow front, ••Flaking, ••Holding pressure, high, ••Needle shut-off valve (impression), ••Mold temperature, too low

Figure 147, ABS vacuum cleaner housing (M = 8, AL), damaged part with cold-flow front (red arrows) and entrained molding compound. The pinpoint gate and the impression of the needle shut-off valve (light blue arrow) were originally located under the dome (purple arrow). The flaking (red arrows), with the now-visible impression of the needle shut-off valve, was carried out through pressing the molding compound into the too-cold mold with a high holding pressure (see also Fig. 148).

Figure 148

Figures & Text

••Flaking, ••Holding pressure, high, ••Needle shut-off valve (impression), ••Cracks, ••Mold temperature, too low

Figure 148, ABS vacuum cleaner housing (M = 32, AL), damaged part, detail of twist from Fig. 147. The cause of damage was a flaking (red arrows) of the visible impression of the needle shut-off valve with cracks in the environment (light blue arrows), due to a high holding pressure and a too-low mold temperature.

219



Figure 149 ••Hot air treatment with heat gun, ••Flaking with cold plug, ••Direct gate, large

Figure 149, SB handle (M = 20, AL) with flaking (cold plug, red arrow) and a large direct gate (blue arrow). After a hot air treatment with a heat gun, the flaking also becomes plastically visible (white arrow). Cause was a high injection rate into a too-cold mold (see also → hot air treatment and → flaking).

Figure 150

Figures & Text

••Molding compound, cold, entrained

Figure 150, ABS vacuum cleaner housing (M = 25, AL) with cold-flow area and entrained, cold molding compound to about 688 µm in length. A hot air treatment with a heat gun helps the present cold-flow area to become more plastic and more visible. Damage was caused by a high injection rate into a clearly too-cold mold (see also → hot air treatment and → flaking).

220



Figure 151 ••Tightening torque, too high, ••Residual stresses, too high, ••Cold-flow lines, ••Mold temperature, too cold

Figure 151, HDPE screw cap (M = 10, AL, damaged part) with crack and cold-flow lines. Damage cause was a too-cold mold temperature. As a result, excessive residual stresses developed in the molded part (molded part stresses), which superimposed during screwing with a high tightening torque (see also → molded part stresses, → cold-flow lines, and → mold temperature).

Figure 152

Orange skin

Cold-flow lines

Vacuoles

Figure 152, POM carrier (M = 28, AL, damaged part) with cold-flow lines, orange skin, and vacuoles close to the fracture area at the dome. The molding compound flowing into the mold cooled too quickly as it became in contact with the mold, and cold-flow lines on the molded part surface, orange skin (“goosebumps”), and vacuoles developed because the gate froze. A too-early dropped holding pressure can also cause vacuole formation. The fracture cause in this case was a too-cold mold temperature (see also → cold-flow lines, → holding pressure, → orange skin, and → vacuoles).

221

Figures & Text

••Gate, frozen, ••Dome fracture, ••Cold-flow lines, ••Holding pressure, too short, ••Orange skin, ••Vacuoles, ••Mold temperature, too cold



Figure 153 ••Molded part surface, tortured, ••Cold-flow areas, ••Orange skin in the ejector area, ••Processing, too cold

Figure 153, ABS/PC housing, polymer blend (M = 8, AL) with a tortured molded part surface, cold-flow areas (1), and orange skin (2). The cause of damage was clearly too-cold processing. Experience shows that the mold temperature is mostly too low. It is often set too low because it increases the cooling rate of the molded parts (according to the business managers), the number of parts/time, and the profit through a reduction in unit costs. But such a view has often led to an expensive recall and image loss.

Figure 154

Figures & Text

••Fire prevention equipment, ••Sink marks prevented through propellant additive, ••Molding compound, too cool, ••Cold-flow area, ••Material costs, optimize, ••Propellant additive

Cold-flow area Figure 154, PC electric housing (M = 50, AL-DF) with 5% propellant and fire prevention equipment. There is a pronounced cold-flow area, close to the gate (arrows) in the surface, because the molding compound was too cold. A propellant should reduce shrinkage, sink marks (especially in thick-walled molded parts), and the weight, therefore lowering the material cost per unit through molding compound savings. Fire prevention equipment also reduces the tendency for fire at spark formation.

222



Figure 155 ••Weld line structure, ••Molding compound, too cold, ••Orange skin texture, ••Edge bead (similar to an over-injection), ••Mold wetting, poor

Orange skin texture

Figure 155, PS rocker switch (M = 15, AL). The faulty molding part has a weld line (center top), an orange skin texture, and an unwanted edge bead (blue arrows) due to poor mold wetting (similar to an over-injection). In this area, the molding compound could not properly fill the mold anymore. The edge bead barely touched the mold surface and is therefore is not actually over-molded. Damage was caused by a too-low temperature of the injected molding compound. Such errors are also caused by a too-early dropped holding pressure or a very long flow path in the mold (see also → over-injection).

Figure 156

Figures & Text

••Molding compound temperature, too low, ••Homogenization time, too short, ••Orange skin texture

Orange skin texture

Figure 156, SAN door frame (M = 6, AL) with orange skin texture. The molded part surface is nearly smooth in the subsequent section. The cause was a too-short homogenization time and an associated too-low molding compound temperature during injection molding into the mold (see also Fig. 157 and → homogenization).

223



Figure 157 ••Machining marks, impressed, ••Injection speed, too slow, ••Cold-flow line with similar weld appearance, ••Mold post-treatment

Cold-flow line

Figure 157, SAN door frame (M = 6, AL), continuation of Fig. 156 in another area with a cold-flow line similar to the weld line and a mold impression with circular machining marks on the right edge of the figure (just faintly visible). The machining marks probably originate from a milling cut in the mold manufacture or a later post-treatment. The cause of the cold-flow line was a too-slow injection (see also → cold flow).

Figure 158

Figures & Text

••Gate with cold-flow lines, ••Record grooves,

Figure 158, PC water meter indicator (M = 25, AL). The small water meter indicator has distinct, concentric cold-flow lines on the pinpoint gate. These are also called record grooves in technical language. Its cause was too-cold mold temperature (see also Fig. 162, → cold flow, and → mold temperature).

224



Figure 159 ••Gate (ring gate), ••Weld line, ••Cold-flow lines, fine, ••Mass streams M1, M2, and M3 ••Y-weld line

Ring gate

Flow path end Figure 159, PA4.11 water housing (damaged part, M = 1 : 1) with a ring gate and fine cold-flow lines (weld lines) through an unexpected confluence of three mass streams M1, M2, and M3, which formed as a result of core offset (see also Fig. 160 and → cold flow).

Figure 160

Figures & Text

••Weld line, ••Weld line area with parabolic cold-flow lines, ••Flow resistance, ••Cold-flow lines, parabolic, ••Core flowing, ••Core offset, ••Mass flows, ••Cross-flow, ••Y-weld line

Figure 160, PA4.11 water housing (M = 12, DL + low POL). Detail from Fig. 159. A weld area with cold parabolic flow lines developed during injection (top right in the figure) into a mold with a long, cylindrical core, at core flowing. The two mass flows, M1 and M2 (Fig. 159), were flowing perpendicular to the injection direction (cross-flow) and met with a back-flowing (from the mold end) of mass flow M3. The cause was a high injection pressure. This caused a core offset and unequal flow resistances at the core diameter. Thus, the molding compound divided itself into the mass flows M1, M2, and M3 during injection. Three mass flows directed against each other form a three-lined Y-weld. But here a single-line weld area was created though the predominant flow pressure of the mass flows M1 and M2 (cross-flow), such as in the convergence of two mass flows. The weld line strength is only good if the mass flows “weld” at the highest possible temperature. It becomes poorer with increasing visibility (see also → weld line and → cold flow).

225



Figure 161 ••Orange skin, typical, ••Mold temperature, too low, ••Molding compound temperature too slow, ••Mold filling, too slow

Figure 161, ASA housing, damaged part (M = 12, AL) with orange skin on the molded part surface. Cause was a too-cold mold temperature. The same error also occurs at a too-low molding compound temperature, a too-slow mold filling, and at long flow paths (see also → cold flow).

Figure 162

Figures & Text

••Cold-flow lines, ••Record grooves, ••Mold temperature or molding compound temperature, too low

Figure 162, SAN hook (M = 30, AL) with cold-flow lines (“record grooves”) on the pinpoint gate. Cause of the complaint was probably a too-cold molding compound temperature during injection. However, because a too-low mold temperature could have also been present, the client received the phone message that both a too-cold mold and molding compound temperature could be to blame. Subsequently, the client pulled back the job (see also Fig. 158 and → cold flow).

226



Figure 163 ••Film gate, ••Cold plug, ••Dead corner

Figure 163, PA6 housing, primary colored and unpainted (M = 1 : 1) with cold plug (red arrows) in the direction of the mold filling (blue arrows, see also Fig. 164). The housing was filled through two film gates (blue arrows). A cold plug is cooled molding compound particles (e.g., from a “dead corner”), which is usually flushed to the mold surface, close to the gate (see also → cold plug, → dead corners).

Figure 164 ••Cold plug by shearing

Filling direction

Figures & Text Figure 164, PA6 housing, primary colored and unpainted (M = 31, AL), detail from Fig. 163, with a cold plug in the flow direction of the mold filling. The film-like cold plug surface is crimped due to a shearing of the molding compound during the filling and bonding to the mold surface.

227



Figure 165 ••Nozzle, axially not aligned, ••Nozzle tip, knocked out, ••Air entrained, ••Air streaks, ••Mold bushing, knocked out

Figure 165, PCTFE bushing (M = 8, AL) with air streaks. This error could be confused with a cold flow. However, when injecting, air was entrained with sharply defined flow front (left), because the nozzle tip of the injection unit is not axially aligned to the mold bushing. Such errors also happen when the nozzle tip or the mold bushing are knocked out in use (see also → cold flow).

Figure 166

Figures & Text

••Mold impression, poor, ••Molding compound flow, reduced, ••Mold temperature, very cold

Figure 166, PE clamp (M = 15, AL) with very cold shaped surface. A poor impression in the mold produced defects in the molded part surface due to an incomplete and poor mold wetting. The reasons for this are a reduced molding compound flow at a too-low mass, mold temperature or molding compound temperature, a too-slow injection speed, or too-low injection pressure (see also → cold flow and → mold temperature).

228



Figure 167 ••Cold-flow areas, distinct, ••Cold-flow lines

Figure 167, POM gear wheel 5 (M = 8, AL), damaged part. The gear wheel has distinct cold-flow areas with cold-flow lines (see also Fig. 168 and → cold flow).

Figure 168 ••Wetting error of the molded part surface, ••Flow viscosity, high, ••Cold-flow lines, distinctive

Figures & Text Figure 168, POM gear wheel 5 (M = 16, AL), damaged part. This detail from Fig. 167 has distinct flow lines cold (cold flow) in the gear surface. Cause of damage: There was a too-high flow viscosity in the area remote from the gate during the cooling of the molding compound in the mold. Therefore, the mass solidified before the complete filling of the mold and could therefore not completely wet the mold surface (see also → cold flow).

229


LM Subchapter: Laminating

Figure 169 Bubble

••Contrasting with DIC-DL and aperture, ••Bubble formation in the adhesive, ••Lamination, ••Adhesive application, too early, ••Layer structure (laminating film), ••Warm exposure

Figure 169, PVC-U window profile section (M = 200, DIC-DL with partially closed aperture), 10 µm thin section. A false DIC slider 10x/0.30 was intentionally inserted for a clear contrast. Bubbles were generated in the laminating film (layer structure: PMMA/PVC/adhesive) after 0.5 h exposure in a convection oven at 150 °C. The PVC-U profile was initially primed with a polyurethane-containing dichloromethane (solvent), and the laminating film is applied with a PUR hot adhesive after drying. There are several systems of aqueous polymer primers. However, they usually only contain small amounts of solvents such as methylpyrrolidone (N-methyl-2-pyrrolidone), or chlorinated hydrocarbon (carbon tetrachloride). Therefore, the cause of the damage was obviously an early-applied adhesive after a too-short predrying, and the bubbles formed due to diffused solvent (see also Fig. 170).

Figures & Text

Bubble

Figure 170, PVC-U window profile section (M = 200, DIC DL + -plate and partially closed aperture), 10 µm thin section. Details in Fig. 169. A -plate was intentionally added to the incorrectly inserted DIC slider 10x/0.30 for a better color contrast. Granted, this was no further evidence, but it was a beautiful picture in brochure quality. In a microscopic examination, the depth of statement of different contrast methods should be tested. Every now and then there are potential seemingly nonsensical combinations of unexpected contrasts (see also Fig. 171, → aperture, → DIC slider, → thin section, → contrast method, → lambda plate).

230

Figure 170 ••Contrasting with DIC-DL, -plate, and aperture, ••Bubble formation in the adhesive, ••Warm exposure


LM Subchapter: Laminating/Adhesive bonding

Figure 171 ••Contrasting with DL-POL + -plate + DIC and partially closed aperture, ••Laminating film, ••Embossing film, ••Layer structure (lamination)

Figure 171, PVC-U window profile section with a PVC embossing film (M = 500, DL-POL + -plate + DIC and partially closed aperture). An 8 µm thin section through the layer structure shows a blue coloration and bubbles in the otherwise low-contrast, water-clear adhesive layer, in an intentionally incorrectly inserted DIC slider (10x/0.30 instead of 50x/0.75). The PVC laminating film (wood grain decor with PMMA cover film) was laminated to the PVC-U window profile with a polyurethane adhesive. For low-contrast samples, the courage of a seemingly senseless combination of contrasting methods is always recommended (see also → aperture, → DIC slider, → contrast methods, → lambda plate).

Figure 172

Figures & Text

••Adhesive, missing, ••Ultrasonic testing (UT), ••Nondestructive testing

Figure 172, PVC bonded socket joint (M = 1 : 1) glued to a PVC pipe. The adhesion area between the bonded socket joint and the pipe surface was scanned and measured with ultrasonic nondestructive testing. The areas with good adhesion showed identical readings with low tolerance deviation. This was also true for the discovered, unbonded areas, only their reading was much lower. Thus, all areas were found and identified without adhesive. These are the drawn, shaded surfaces on the outside of the joint bonded socket. The sloppy bonding led to a leak after a short time with large water damage.

231


LM Subchapter: Adhesive bonding

Figure 173

Adhesive

••Drop of glue, penetrating, ••Molded part stresses, ••Stress cracking due to solvent

Fracture edge Figure 173, PA6 car door handle (M = 6, AL), damaged part. The car handle broke when opening the car door. As the examination revealed, the cause of the damage was an accidental drop of glue on the car door handle during interior work on the car. The adhesive drops, which contain solvent, acted to cause tension cracking, and the freed molded part stresses caused the fracture, together with the force of opening and closing the car door (see also → molded part stresses, → media that can cause tension cracking, and → wetting agent test).

Figure 174

Figures & Text

••DVS standard 2221-1, ••Chamfer (bevel) on the pipe is missing, ••Socket joint, not according to the standard, ••Pipe end, sawed-off angle

Figure 174, PVC socket joint, damaged (M = 1 : 1). When flowing through a PMMA dispersion of only 0.6 bar, the PVC pipe (sample 2) dislodged itself from the PVC adhesive sleeve (sample 1) at a small pipe pressure. The PMMA dispersion (blue arrows) was flowing out (also from the connected large container) and covered the pipe surface (and the factory hall) like a clear coat. The leached pipe end (sample 2) had no chamfer and was improperly diagonally sawed according to the DVS 2221-1 standard (arrows 1 and 2). This reduced the adhesive surface and a large part of the adhesive was pushed out by the sharp end of the pipe during insertion into the sleeve (Fig. 175). Some spots on the adhesive surface can suggest small adhesive residues (Fig. 176). No stress-whitening can be seen on the adhesive surface, as for a good bonding (see also Figs. 175 and 176).

232


LM Subchapter: Adhesive bonding

Figure 175 ••Socket joint, not according to the standard, ••Adhesive residue and plastic bead is missing on the socket

Figure 175, PVC socket joint, damaged (M = 1 : 1). This detail from Fig. 174 shows no clear adhesive residues on the internal surface of the socket (sample 1, Fig. 174), and no fully rotating bead of adhesive on the insertion end (arrows; see also Fig. 176).

Figure 176

Figures & Text

••Socket joint, not according to the standard, ••THF adhesive visible under UV radiation at 366 nm, ••THF adhesive, too old

Figure 176, PVC socket joint, damaged (M = 1 : 1). The pipe end (see sample 1, detail from Fig. 174) has little adhesive residue on the adhesive surface and a not completely encircling bead of adhesive (see Fig. 175, red arrows). The THF glue “Tangit” used contained the solvent tetrahydrofuran THF and up to 30% dissolved PVC content to bridge the gap. This THF adhesive shone bluish under an ultraviolet radiation in the wavelength range of 366 nm. Sporadically bright blue border areas have been detected as adhesive residues on the adhesive surface. The cause of the damage was an improper preparation (see Fig. 174) and an insufficient adhesive application, as occurs, for example, in an aged adhesive with an expired date of use.

233


LM Subchapter: Design

Figure 177 ••Tightening torque, too high, ••Bisecting samples (preparation), ••Overloading, mechanical, in the round thread, ••Screw joint is leaking

Screw cap

Crack beginning

Figure 177, PPO water tank (M = 6, AL). A polished sample through the screw cap proves that the beginning of a crack is initiated at the sealing surface by mechanical overloading. The sealing surface of the cap underwent a too-high torque on the container surface that created a partially circumferential crack. With such damage, a bisecting sample is beneficial to improve the the interaction of the individual parts together. A simple saw cut or separating cut with a diamond saw is often sufficient.

Figure 178

Figures & Text

••Tightening torque, too high, ••Thread, worn on one side, ••Design errors, ••Screw joint is leaking

Figure 178, HDPE screw cap (M = 8, AL, damage part). The screw cap was tightened wrongly because the thread was only worn on one side when screwing (Fig. 179, left) and the glass thread slipped through. Design errors and a high tightening torque when screwing led to the angled seat of the screw cap and the subsequent crack. Thus the contents of the bottle leaked.

234



Figure 179 ••Thread base, sharp, ••Design errors, ••Sample preparation with bisection, ••Round thread with a sharp thread base

Figure 179, HDPE screw cap (M = 6, AL). For the examination, the new part was cut through the center with a scalpel. In the left side of the picture, just a half-sided thread on the bottle neck is visible (between the arrows). Therefore, the screw cap tilted when screwing. A reliable plastic screw should have a round thread without a sharp thread base, as in this case (black arrows). There, cracks appeared on the damaged part (Fig. 178) (see also → design error).

Figure 180

Figures & Text

••Comparative study, ••Nonrounded edge, ••Notch is initiating tension cracking

Nonrounded edge

Figure 180, PA6 GF15 clamping part, good part (M = 12, AL). A polished sample through the sample cross-section shows no microvacuoles. The sample, with a nonrounded edge in the main loading area, is very insufficient and can act as a notch that initiates tension cracking (see also Fig. 181).

235



Figure 181 ••Comparative examination, ••Mass accumulation, ••Microvacuoles, ••Notch initiates tension cracking

Figure 181, PA6 GF15 clamping part, damaged part (M = 6, AL). A polished sample through the sample cross-section shows reddish microvacuoles (blue arrow) in a mass accumulation. Together with the microvacuoles, the transition without a rounded edge acts in the main loading area in Fig. 180 as a notch that initiates tension cracks and causing the fracture of the clamping part at load (see also → notch, → design errors, and → mass accumulation).

Figure 182

Figures & Text

••Gate with cold-flow lines, ••Cold-flow lines concentric, ••Design change, ••Protect statements from the customer, ••Mold change

Sample 1

Sample 2

Figure 182, PC water meter indicator (M = 25, AL). Samples 1 and 2 have varying, pronounced concentric cold-flow lines at the pinpoint gate. Sample 2 was presented to us as a damaged part and sample 1 as an inconspicuous good part of this series. The molded parts, the mold, and the processing parameters remained unchanged for years. However, as a microscopic examination revealed, the damaged part sample 2 has somewhat clearer cold-flow lines (cold flow). And there is obviously also a mold change because the indicator of sample 1 is slightly longer and the pinpoint gate was dislocated. Such claims are commonly used in reports (protection claims). The alleged good parts (reference samples) are actually unchecked damaged parts, and after a closer examination, it then becomes clear that the batch quality, processing parameters, and the mold were subsequently changed. Such allegations should be recognized promptly by an appraiser and quality inspector (see also → masterbatch change, → cold flow, and → processing parameters).

236


LM Subchapter: Contrast

Figure 183 ••Contrast method DL in comparison, ••Thin section, ••Whole or residual granulate?, ••Matrix, ••Pigment conglomerate, ••Vacuole

Figure 183, PP panel (M = 50, DL). A 10 µm thin section through a PP molding shows pigments in normal transmitted light and small pigment conglomerates in the matrix. But what is in the center of the picture; a blowhole, a vacuole, a hole, or an unmelted granulate? (see also Figs. 184 to 186, → thin section, → granulate, unmelted, → contrast method, → matrix, → pigment conglomerate, → vacuoles and blowholes).

Figure 184

Figures & Text

••Contrast method DL-PH in comparison shows fine density differences, ••Refractive index, ••Density differences, ••Types of plastics, ••Whole or residual granulate? ••Phase contrast, ••Polarization, ••Spherulites

Figure 184, PP panel (M = 50, DL-PH), as detailed in Fig. 183. A 10 µm thin section through the PP molded part clearly shows an unmelted granulate (residual granulate) with spherulites in transmitted light phase contrast DL-PH. When looking at the picture, it reveals that the phase contrast results in a polarization-like effect because spherulites are visible in the unmelted granules. A polarization is generated with crossed polarizers, such as for transmitted light polarization DL-POL. However, because a fine transmitted light phase contrast DL-PH makes refractive indices visible, the fine differences in density, and thus the density difference in spherulites, become visible between the amorphous and semicrystalline regions. The contrast is however lower than with a polarization (see Figs. 183, 185, and 186, → refractive index n, → plastics materials, → phase contrast, → polarization, and → spherulites).

237



Figure 185 ••Contrast method DL-POL in comparison, ••Double refraction, ••Fabric structure, semicrystalline, ••Polarization contrast, uncolored, ••Residual granulate with spherulites, ••Spherulites in the residual granulate

Figure 185, PP panel (M = 50, DL-POL), as detailed in Fig. 183. A 10 µm thin section through the PP molded part clearly shows an unmelted granulate with spherulites in the uncolored transmitted polarization contrast. Birefringent media, such as spherulites, are only visible in transmitted light with polarization (colored and uncolored; see also Fig. 186). A polarizer is therefore always necessary for transmitted light examination of semicrystalline microstructures in plastics (see also Figs. 183, 184, and 186, → birefringence, → granulate, unmelted, → polarization contrast, and → spherulites).

Figure 186

Figures & Text

••Contrast method DL-POL +  in comparison, ••Lambda plate makes POL colored, ••Sample stage rotation changes colors

Figure 186, PP panel (M = 50, DL-POL + -plate), as detailed in Fig. 183. A 10 µm thin section through the PP molded part shows an unmelted granulate with spherulites in colored transmitted light-polarization contrast with lambda plate, as shown in Fig. 185, but in color. The lambda plate turns from uncolored to a colored polarization contrast, but otherwise, no other statements can be made because the coloring in the figure varies with the sample stage rotation (see Figs. 183 to 185, → lambda plate, and → polarization contrast).

238



Figure 187 ••Contrast method AL in comparison, ••Incident light contrast, ••Microscopic examination, ••Polished sample

Figure 187, C-PVC drinking water pipe DN 20, uncolored (M = 100, AL). Different particles can be seen under a microscope in the normal incident light through a polished sample through the pipe cross-section. As thermal examinations showed, there was an uncolored C-PVC (C-PVC is a post-chlorinated polyvinyl chloride; see also Figs. 188 to 190 and → microscopic examination).

Figure 188

Figures & Text

••Contrast method DF-AL in comparison, ••Dark field contrast, ••Pigment conglomerates, ••Polished sample

Figure 188, C-PVC drinking water pipe DN 20, uncolored (M = 100, DF-AL), as detailed in Fig. 187. The polished sample with the different particles gives more information in the dark-field incident light than in normal incident light (Fig. 187). So now white and black pigment conglomerates as well as red pigment conglomerates are seen (see Figs. 189 and 190 and → dark field contrast).

239



Figure 189 ••Contrast method AL-DIC in comparison, ••Differential interference contrast, ••Polished sample

Figures & Text

Figure 189, C-PVC drinking water pipe DN 20, uncolored (M = 100, AL-DIC), as detailed in Fig. 187. If the polished sample is examined with different particles in incident-differential interference contrast, then there is no appreciable difference to the normal incident light contrast in Fig. 187 (see also Figs. 188 and 190, → differential interference contrast).

Figure 190 ••Differential interference contrast with -plate, ••Contrast method AL-DIC + -plate in comparison, ••Polished sample

Figure 190, C-PVC drinking water pipe DN 20, uncolored (M = 100, AL-DIC + -plate), as detailed in Fig. 187. In a microscopic examination of the polished sample with the different particles in incident differential interference contrast and an extra -plate, a colored contrast is created, but there is no significant difference to the normal incident light contrast in Fig. 187 (see also Figs. 187 to 189).

240


LM Subchapter: Contrast/Crystals

Figure 191 ••Illumination with low incident light shows internal crack, ••Illumination, correct, ••Orange skin

Crack

Figure 191, PC handle for a water meter (M = 25, AL) with crack in the weld line and orange skin. Through oblique, bright light from the right and at the same time a little less from the top left, a translucent, axial internal crack is visible in the PC handle. The internal crack would have remained invisible in normal incident light. Thus, for example, a cold lighting should have two movable optical conductors (“swan necks”). Then the sample illumination can be controlled, as in the figure. The illumination was carried out using an optical conductor, close to the right surface of the sample for a direct “transmission” and with the other optical conductor, from a greater distance, the illumination of the sample surface from the upper left (see also → orange skin).

Figures & Text

Figure 192 ••Crystal growth in vitamin C

Figure 192, Crystals (M = 100, DL-POL + -plate) of ascorbic acid + L (vitamin C). About 1 g of ascorbic acid was wetted on a glass slide with a little distilled water. Then within 72 h, the crystals grew in a convection oven at 30 °C.

241


LM Subchapter: Crystals

Figure 193 ••Crystal growth in white sugar

Figure 193, Crystals (M = 50, DL-POL) of white sugar. About 1 g of white sugar was wetted on a glass slide with a bit of distilled water. Within 64 h, the glorious sugar crystals grew in a convection oven at 35 °C (see also Fig. 194).

Figure 194

Figures & Text

••Crystal growth in white sugar, ••Spherulites of PA are similar to sugar crystals

Figure 194, Crystals (M = 25, DL-POL + -plate) of white sugar. Approximately 1.20 g of white sugar was wetted on a glass slide with a little distilled water. Within 60 h more compact sugar crystals grew in a convection oven at 38 °C (see also Fig. 193).

242


LM Subchapter: Plastic materials

Figure 195 ••TPE thermoplastic elastomer, ••Macromolecule bonds, physical

Figure 195, TPE spring element (M = 1 : 1) as used for a slatted frame in a bed mattress. TPE is a physically crosslinked but still thermoplastic material. This thermoplastic elastomer can be injection molded or extruded. Unlike an elastomer with a chemical macromolecule bond, the physically crosslinked macromolecule compounds dissolve when heated again (see also → thermoplastic elastomer TPE).

Figure 196 ••Wood plastic composites, WPC, ••Matrix materials in WPC, ••Processing aids, reinforcing agents

Figures & Text Figure 196, WPC (wood plastic composites, M = 1 : 1, AL). WPC-plastics are used in the automotive, construction, furniture, and toy industries. They are also used as materials for flooring, paneling, and fences. For WPC products, the properties are directly influenced by a variation of the wood portion. Matrix materials are polypropylene PP or polyethylene PE. The cohesion between the polar wood fiber and nonpolar polymer matrix improves adhesion promoters (compatibilizers). Additionally, other processing aids are required: antioxidants, fungicides, masterbatches, and UV stabilizers. For reinforcing, in addition to wood fibers, the following are used as well: bast fibers of hemp, fruit fibers from coconut, esparto, and hard fibers from pineapple, kenaf, seed fiber from cotton, or kapok.

243


LM Subchapter: Painting

Figure 197 ••Paint errors (paint flow), ••Error, systematic (paint error), ••Paint surface with paint wrinkles, ••Influence of gravity

Figure 197, PA6 inside a door handle frame, recessed grip (M = 30, AL) with a typical soft paint damage (paint flow) at the lower bottom edge. The soft paint damage always occurred at the same place, making it a systematic error. Cause: When painting the sample, which was hanging in a painting rack, more paint than desired was flowing to the bottom edge, following gravity (see Fig. 198 and → painting error).

Figure 198

Figures & Text

••Paint errors (paint flow), ••Error, systematic, ••Paint surface with paint warps, ••Paint thinner, excessive

Paint warp

Figure 198, PA6 inside door handle frame, recessed grip (M = 30, Al), detail from Fig. 197. A parallel-guided scalpel cut through the paint surface shows a bubble-free coat. And a 10 µm vertical thin section through this region showed a significant excess of the prescribed coating thickness of more than 30%. The foundation was unremarkable and equally thick. Thus, sufficient proof was provided that the foundation was not the cause of the damage (as alleged), but too much paint thinner probably was. The damage developed at the bottom edge, following gravity.

244



Figure 199 ••Paint errors (paint flakes), ••Old paint residue, ••Pressure fluctuations during painting, ••Flake, ••Paint nozzle washed, ••Paint system, aged

Flake

Closed paint surface under the flake Figure 199, PBT fan blade (M = 30, AL) with silver-gray paint. The area under the flake, which is loosened with a dissecting needle (chip-like paint error), is continuously painted. This means that the approximately 700 µm long flake developed at the end of painting by whirled old paint residue in the painting chamber. The cause of the error was old paint residue in the painting chamber (see also Fig. 200).

Figure 200 ••Paint error, ••Paint bubbles are paint drops, ••Scalpel cut through supposed paint bubble

Figures & Text Figure 200, PBT fan blade (M = 33, AL) with fine “paint bubbles” up to 40 µm in diameter in silver-gray paint. After horizontally cutting a fine “paint bubble” with a scalpel, it became clear that the “paint bubbles” were ball-like paint drops on the closed paint surface of the molded part. The cause of the paint drops was paint flight during painting of the back by pressure fluctuations of the paint layer, a washed-out nozzle diameter, and an aged painting system (viscosity increase; see also Fig. 199).

245



Figure 201 ••Surface, unpainted, is error-free

Unpainted surface

Figure 201, ABS molded part surface, unpainted (M = 6, AL), with a flawless structure and without surface damage, foreign particle inclusions, efflorescence, or protruding glass fibers (see also Fig. 202).

Figure 202

Figures & Text

••Surface is partially well painted and partially poorly painted, ••Primer, poor

Poorly painted

Well painted

Figure 202, ABS molded part surface (M = 16, AL). The examination was done with two molded parts with good and poor painting on the eroded surfaces, as compared to the example in Fig. 201. According to the information from the client, all molded parts were from the same batch, the same cavity, and were injection molded with the same processing parameters. Nevertheless, the paint structure on the left molded part was rougher than on the right, and therefore the eroded surface of the molded part is still clearly visible. The 10 µm thin sections showed that a sufficiently thick undercoat was missing under the poorly painted coat.

246



Figure 203 ••Double painting, accidental, ••Error at the demolding agent, washed off, ••Cooking test generates paint bubbles, ••Demolding agent residues on the molded part surface

Figure 203, ABS cover, painted, (M = 30, AL). In a cooking test, paint bubbles were created in the paint layer. For easier demolding of the ABS cover, a demolding agent was sprayed into the injection mold before each injection. It had to be washed off before painting again. Cleaning agent was removed from a bucket using a cloth and the demolding agent was wiped off. After frequent repetition, an enrichment of the demolding release agent was created in the bucket. The first 320 treated covers still remained inconspicuous, but the later ones increasingly became contaminated. And due to the wiping movement of the contaminated cloths, the later paint bubbles were arranged like pearl chains. The microscopic examination also showed that the cover was painted twice by mistake. The causes of damage were thus an unintended double coating and double contamination by the demolding agent due to washing the supposedly unpainted plastic surface twice (see Fig. 204).

Figure 204

Figures & Text

••Double painting, accidentally, ••Paint outbreaks, ••Embrittled paint layers, ••Multilayer coatings

Figure 204, ABS cover painting (M = 30, AL). The cover was painted twice by mistake (multilayer coating). At a higher magnification, the two embrittled paint layers are clearly visible at the edges of the paint outbreaks (see Fig. 203).

247



Figure 205 ••Soft paint with bubbles

Open bubbles in the paint

Figure 205, PA6 GF30 frame (M = 25, AL) with silver-effect soft paint. The outer edge of the left frame has occasional open bubbles in the area of sight (arrows; see also Fig. 206 and → painting error).

Figure 206

Figures & Text

••Soft paint with bubbles, ••Paint outgassing?, ••Residual moisture, blamed for paint bubbles?

Figure 206, PA6 GF30 frame with silver-effect soft paint (M = 50, AL-DF), detail 1 from Fig. 205. The painter thought that excessive residual moisture in the molded part was to blame for the partial bubbles (arrows). For the examination, the paint surface in the damaged area was removed and turned over with a scalpel, parallel to the surface. The turned-over paint piece (arrow 1) had fine bubbles in the paint. Although polyamide-6 (PA6) can absorb water, the bubbles were created in soft paint in the figure. Residual moisture in the molded part, however, is distributed in the entire molded part, and certainly not at only one point. Therefore, the bubbles would have spread over the entire painted surface. Cause of damage was therefore a still-present but no longer recognizable outgassing during painting (for example, from some solvent in the boundary area). FTIR analysis (point analysis) of the bubble was not requested.

248



Figure 207 ••Effect paint with solvent penetration, ••Solvent content, reduce, ••Polymer blend with paint intrusion, ••Tempering prevents stress cracks

Figure 207, PA/PE hub cap, polymer blend with Al-effect paint (M = 50, DL). In an 8 µm thin section through the solvent-based Al-effect paint on the hub cap, the solvent influence (light area) in the plastic boundary layer is clearly visible under the paint. The solvent penetration caused stress fractures in some spots in the injection-molded wheel cover. Remedies are to temper the hub cap for stress reduction, increase the mold temperature, or reduce the solvent content (PA/PE is a polymer blend of polyamide with polyethylene, Al = Aluminum).

Figure 208

Figures & Text

••Sink marks, ••Painter was not to blame, ••Molded part cracks create paint cracks, ••Blame (whose fault is it?)

Figure 208, CAB housing, painted (M = 25, DL-POL + -plate, low polarization). A 20 µm thin section was manufactured through the molded part cross-section with a thin Al-effect paint and clear paint. Many cracks in the molded part ended in the molded part surface, without damaging the effect coat. They stood out as sink marks of the paint surface. Cause for the complaint was high molded part stresses due to too-cold processing during injection molding and not a faulty painting, as originally claimed by the counterparty. The blame lies therefore with the counterparty and not with the painter (see also → sink marks, → molded part tensions, → injection molding, and → processing).

249



Figure 209 ••Al-evaporation of ABS with yellow topcoat (“gold sputtering”), ••Contrast method AL-DIC +  particularly good for metalworking vaporization

Figure 209, ABS molded part with a “gold sputtering” (M = 100, AL-DIC + ). The molded part, which was coated with a white base coat, was first vaporized with aluminum Al and then covered with a transparent yellow-colored topcoat. This created a gold-colored surface. The lint, which is integrated under the topcoat, comes from one of the used cleaning rags that were not clean. Shiny surfaces, such as a metal vapor, are particularly well suited for studies in reflected differential interference contrast. ABS is an acrylonitrile butadiene styrene copolymer (see also → differential interference contrast).

Figure 210

Figures & Text

••Al-vapor evaporation of SB with top coat (“gold sputtering”) ••Paint drops, deformed, ••Paint with solvents, refreshed, ••Paint aging

Figure 210, SB molded part with “gold sputtering” (M = 200, AL-DIC + ). The molded part, which is painted with a white base coat, was vaporized with aluminum and then painted with a transparent, yellow-colored topcoat. This resulted in the gold color. The integrated error of the topcoat is deformed paint drops. The cause of damage was aged paint that has been refreshed with a badly mulled solvent additive (see also → painting error).

250



Figure 211 ••Paint error, ••Wettability, reduced, ••Flame retardant, ••Adhesive strip method, ••Conditioning of PA6 GF30 with PE instead of H2O, ••Paint delamination (2C-hard paint)

Figure 211, PA6 GF30 armrest, polymer blend conditioned with PE (M = 8, AL), damaged area. The abrasion-resistant 2C-hard paint delaminated in a brittle manner. Instead of conditioning the armrest with water, a PE masterbatch was mixed in. The PE content, which is therefore present in the plastic surface, and an additional flame retardant, decreased the wettability of the plastic surface. The paint back side, which was tested with the adhesive strip method, showed a good impression of the surface structure. But the molded part surface, which was exposed with the adhesive strip method, had a poor wettability of only 29 mN/m (measured with Arcotec pin) instead of 40 mN/m. Additional damage in another area is shown in Fig. 213 (see also Fig. 212, → wetting tests, → paintability, and → painting error).

Figure 212

Figures & Text

••Painting error (bubble areas), ••Paint surface is defective (according to the client)

Figure 212, PA6 GF30 armrest, painted and conditioned with PE (M = 20, AL). Such a structure should have the visible side of the coating surface in Fig. 211. In this picture, it was also painted defectively and had blistered areas (see Figs. 211 and 213).

251


LM Subchapter: Painting/Lasering

Figure 213 ••Painting error, ••Illumination with oblique incident light, ••Molded part surface is flawed, ••Glass fibers are poorly embedded, ••Matrix adhesion of the fibers is poor, ••Mold wetting, poor, ••Mold temperature, lower

Figure 213, PA6 GF30 armrest with conditioned PE, painted damaged area (M = 33, with a deep horizontal AL). The painted surface of the molded part showed highly textured areas at 33-fold magnification. These are areas of the molded part surface that were poorly molded in the mold and over-painted with base and top coat with poor integration of the plastic fibers. Damage cause was a poor mold impression due to a too-low mold temperature. This created the rough surface, which could also not be smoothed by the base and top coat application (see Figs. 211 and 212).

Figure 214

Figures & Text

••Laser writing faulty, through ND-YAG laser, ••Damaged part

Figure 214, PC printer lid (M = 1 : 1). The damaged part has faulty laser writing (arrows) with repeatedly overwritten numbers from a diode-pulsed Nd-YAG laser (see Figs. 215 to 218 and → lasering of letters and numbers).

252


LM Subchapter: Lasering

Figure 215 ••Laser writing, repeatedly overwritten, ••Laser writing with uneven coloring, ••Damaged part with repeated overwriting

Figure 215, PC printer lid (M = 28, DL combined with AL), detail from Fig. 214, damaged part with uneven green color in the letters (appearing black in transmitted light) and caused by repeated overwriting by the laser (see Figs. 214 and 216 to 218).

Figure 216

Figures & Text

••Laser writing with a clear laser track, ••Good part with a clear line of laser tracks

Figure 216, PC printer lid (M = 28, DL combined with AL), good part. For comparison, a good part has been examined under the microscope in the same area as for the damaged part in Fig. 215. The good part had a clear line of laser tracks (see also Figs. 214, 215, 217, and 218).

253



Figure 217 ••Laser writing with conchoidal fracture areas, ••Conchoidal fractures due to the laser, ••Point heating during lasering, ••Damaged part

Figure 217, PC printer lid (M = 28, DL combined with AL), detail from Fig. 214, damaged part with faulty laser font in polarized transmitted light and conchoidal fracture areas in the matrix due to like an explosive point heating (see also Figs. 214 to 216 and 218).

Figures & Text

Figure 218

Crack

Figure 218, PC printer lid (M = 25, DL combined with AL), damaged part, detail from Fig. 214. A polished sample through the number 750 in Fig. 217 showed a conchoidal crack and a laser penetration depth with carbonation through the entire wall thickness due to an excessive point loading. We suspected as the cause of damage a high heat input by repeatedly running over the numbers with little line spacing. Other causes were thought to be an excessive dwell time or laser energy that is set too high (see Figs. 214 to 217 and → lasering of letters and numbers).

254

••Laser writing with conchoidal crack, ••Carbonation due to laser, ••Laser penetration depth, ••Laser energy, too high, ••Laser-point loading, ••Damaged part



Figure 219 ••Laser writing with foamy bubble structure, ••Lasering aid

Figure 219, POM button with laser marking (M = 200, DL), damaged part, 10 µm thin section with a uniform laser penetration depth but foamy bubble structure. Cause is an inhomogeneous distribution of antifoaming additives (lasering aid) in the molding composition. In the thin section, it is visible as a fine, glassy particle, but it was partially missing on the molded part surface (see also Fig. 220).

Figure 220

Figures & Text

••Laser writing with low-contrast edge area, ••Gas and particle formation during lasering, ••Laser head suction, ••Laser pulsation, ••Laser writing with cloudy structure

Figure 220, POM button with laser writing (M = 25, AL), good part. The letters have a white, cloudy structure (blue arrows) and are low in contrast in the edge area. Causes: The cloudy structure, which is emerging in equidistant areas, indicates laser pulsation or a varying writing speed, for example, due to friction in the laser head guidance. The thin laser beam scans the letters several times in parallel offset and twice as often when crossing intersections. There the energy input was increased (red arrows) and the letters became brighter. The low-contrast edge areas formed by increased heat loss from the low melt volume in the colder molded part wall. Furthermore, gas and particle formation around the laser head could have influenced the laser beam. Even dust particles and released, unhealthy gases (formaldehyde, chlorinated hydrocarbon, benzene, HCl, and so on) result in pollution and corrosion in the environment and blurred letters at a high writing speed. Suction can increase the writing performance up to three times.

255


LM Subchapter: Blowholes

Figure 221 ••Blowholes in POM rail due to entrained air (air injection), ••Outgassing, ••Injection, ••Decomposition, thermal

Figure 221, POM rail (M = 10, AL), injection-molded part with a blowhole (arrows) under the molded part surface caused by entrained air. Blowholes occur, for example, at an insufficient fitting force of the nozzle during injection of the molding compound into the mold by entrained air and also by thermal decomposition or outgassing of molding compound ingredients (see also Fig. 222, → outgassing, → injection, and → decomposition, thermal).

Figure 222

Figures & Text

••Blowholes in POM rail by entrained air, ••Outgassing, ••Block ground sample, ••Fitting force of the nozzle, too low, ••Air from the feed zone, entrained

Figure 222, POM rail (M = 15, AL), detail from Fig. 221. A sample was taken from the area that is marked with a red arrow, and a block ground sample was made. After the removal of the molded part surface with wet abrasive paper (250, 500, and 1200), a blowhole was visible as the cause of the bubble. This was created by entrained air because the injector nozzle was not fitting closely enough onto the mold (the fitting force of the nozzle was too low). Air can also be entrained in the feed zone at the filling funnel (see also → block ground sample and → vacuoles and cavities).

256



Figure 223 ••Blowholes in PVC during extrusion, ••Storage, improper, ••Blowholes due to residual moisture, ••Predrying

Figure 223, PVC panel (M = 6, AL). During extrusion of the PVC panel, many blowholes formed in the extruded surface. The cause was excessive residual moisture in the extruded molding compound due to improper exposure in humid conditions. Gentle predrying would have prevented the blowholes. Basically, a predrying is recommended after extended exposure (see also Fig. 224, → moisture in the molding compound, → blowholes).

Figure 224 ••Blowholes in PVC during extrusion, ••Residual moisture generated blowholes

Figures & Text Figure 224, PVC panel (M = 25, AL), magnification from Fig. 223. The blowholes in the extruded surface were caused by too-high residual moisture in the molding compound. They reach to just below the surface and are occasionally open (see also → residual moisture).

257



Figure 225 Hole

••Blowholes in ABS cover when extruding, ••Air, entrained, ••Blowholes due to entrained air, ••Damaged part with hole

Wall thickening

Figure 225, ABS cover (M = 20, AL), damaged part with hole and wall thickening. The damaged part has a through-hole in the region of a line-like thickening of the wall. The client could not explain it and asked for an examination (see also Fig. 226 and → extrusion).

Figures & Text

Figure 226 ••Blowholes in ABS cover during extrusion, ••Blowholes due to entrained air, ••Damaged part with blowholes

Figure 226, ABS cover (M = 12, AL), damaged part with hole and wall thickening. A polished sample through the elongated wall thickening in Fig. 225 shows many blowholes due to entrained air from the feed zone in the extruded ABS shield. The air was initially collected in various molded part areas and relaxed after leaving the slot nozzle. This created a wall thickening with the expanding bubble. The cause of the hole was probably a big air bubble that expanded near the surface and broke open.

258



Figure 227 ••Fracture surface with ABS blowholes, ••Blowholes due to decomposition, ••Cross-sectional weakening, ••Thermal decomposition creates blowholes, ••Vacuum forming

Blowholes

Figure 227, ABS tray, thermoformed part (extruded damaged part, M = 6, AL) with blowholes in the fracture surface. The blowholes formed as lenticular cavities during flowing of the molding compound. The tray broke in the area of the blowholes due to the cross-sectional weakening. As thermal analysis showed, the molding compound was slightly predamaged after the extrusion of the ABS panel, and the repeated thermal load increased the predamage. The cause of the damage was an outgassing in vacuum-forming due to thermal decomposition of the macromolecular chains with blowhole formation (see also Fig. 228, → plastic analysis).

Figures & Text

Figure 228 ••Blowholes in ABS thermoformed part, ••Blowholes due to decomposition,

Figure 228, ABS tray, thermoformed part (extruded damaged part, M = 10, AL), visible surface of the ABS tray in Fig. 227 with a porouslike structure. This was generated due to the blowholes formed by thermal decomposition with outgassing, just below the surface, in the drainage area of the tray.

259



Figure 229 ••PE blown film, three-layered, ••Extrusion blow molding, ••Air inclusion during lamination, ••Air bubble in PE slurry film

Air bubble Glass fabric

Figure 229, PE slurry film, three-layered PE/glass fiber layer/PE (M = 25, AL) manufactured in extrusion blow molding. Air bubbles (blowholes) were included during lamination of PE films, which are colored with carbon black pigment (see also → extrusion blow molding, → laminating, and → vacuoles and cavities).

Figure 230

Figures & Text

••Confirmed through close cooperation with the client, ••Injector nozzle, renewed, ••Air bubbles in C-PVC fitting, ••Screw speed, too high

Figure 230, C-PVC fitting (M = 25, AL). Line-like cavities were trapped under the pipe surface during injection molding of the C-PVC fittings. Are these now vacuoles or blowholes? Reminder: vacuoles are mostly rugged shrinkage cavities that are often close to each other in the matrix. Blowholes are mostly smooth-walled over-pressure cavities due to outgassing. The cavities, which are shown in the figure during injection, are smooth-walled and beaded distributed air bubbles (blowholes) due to entrained air from the funnel area (at high screw speed). By working closely with the client, the error disappeared, as by our recommendation the screw speed was reduced (and hence a possible chain reduction) and the injection nozzle was replaced.

260


LM Subchapter: Mass swivel

Figure 231 ••Mass swivel (structural inversion with air induction), cause for electroplating error, ••Bath liquid displaced, ••Injecting, turbulent, ••Electroplating errors, ••Structure inversion, ••Mold venting, poor, ••Mold filling, turbulent

Figure 231, PA molded part surface (M = 200, DL-POL + -plate), 10 µm thin section. Such mass swivels (structural inversion) often arise close to the gate during injection molding due to a swirling of already cold molding compound with air induction. Penetrating or protracted bath liquids then lead to usually sharp-edged bubbles in the electroplating layer during electroplating. Cause, for example, was a too-fast (turbulent) injection of the molding compound into the mold cavity. As it is swirled in the colder mold wall, it pulls air, and will then be poorly viscous or not a high viscous “weld.” Thus, such an error may also develop in poor mold venting (see also → structure inversion, → mold cavity, and → mold venting).

Figure 232 ••Mass swivel with strength loss, ••Mold filling, turbulent

Figures & Text Figure 232, PC molded part (M = 25, DL-POL + -plate), 10 µm thin section. Mass swivels, which then “welded” together, develop in cases of rapid injection due to a turbulent mold filling. The molded part also experiences a loss of strength when the mold temperature is very low.

261


LM Subchapter: Media

Figure 233 ••Cracks, brittle cracks in the bending zone, ••Media attack through local medium

Figure 233, PU air hose (M = 18, AL). The delivered PUR air hose was 120 cm long and had partial brittle cracks on the outside, perpendicular to the extrusion direction, but only in a limited range of 1.5 cm in length. The damage is typical for a media attack. In addition to the damaged area on the entire outside of the air hose, no other cracks can be found. Therefore, the cracks developed due to locally dripped chemicals and not as the client asserted due to gaseous chemicals in the atmosphere. Such a local limitation of the brittle cracks would not have been possible with gaseous chemicals.

Figure 234

Figures & Text

••Coloring with Victoria blue, ••Molded part tensions, ••Media attack, ••Media cracks, net-like, ••Victoria blue (powder)

Figure 234, SB cleaning tank (M = 15, AL) with media cracks. The vacuum-formed cleaning tank has been used in a hospital and destroyed by detergents. These generated net-like cracks in the molded part surface strained with molded part stresses. For better visibility, the cracks were colored with Victoria blue (powder dispersed in H2O or alcohol; see also → coloring).

262



Figure 235 ••Copper attack on PP pipe, ••Media attack circular, ••“PP cancer” by copper attack

Figure 235, PP drinking water pipe (M = 31, AL, damaged part). After 8760 hours in a convection oven (hot exposure), a circular media attack was formed at 110 °C in the pipe surface. The circular decomposition from the pipe surface going outward from the polymer matrix penetrated to 4.25 mm. The cause was an attack by copper Cu because a copper pipe was located in front of the PP drinking water pipe in the flow direction. Copper attacks polyethylene PE and polypropylene PP and leads to decomposition of the polymer matrix at prolonged exposure (see also → heat exposure).

Figure 236

Figures & Text

••Molded part stresses, ••Wettability, ••Wetting agent test generated media cracks

Figure 236, SAN filter cup (M = 1 : 1) with media cracks after a wetting agent test in toluene + n-propanol, 1 : 5, and 5 min immersion time (at high molded part stresses also 1 : 10). Wetting agents are tension-crack-causing, weak solvents for plastic materials. With the wetting agent test (according to DIN ISO 175, determination of the behavior against liquids, including water), the size of the molded part stresses of the molded part surface is tested with a test liquid (wetting agents). Implementation: When available, three entire molded parts (samples 1, 2, and 3) should be immersed into the wetting agent; sample 1 should be removed after 5 min, sample 2 after 10 min, and sample 3 after 15 min. The samples should be dried overnight so that the swelling caused by the wetting agent disappears. The released molded part stresses sometimes only become visible through cracks. The sooner cracks occur, the greater the molded part stresses. Because stresses are also released at a sample reduction (sawing), it is recommended to use whole samples (see also → wetting test according to ISO 175:1981, DIN EN ISO 175).

263



Figure 237 ••Media cracks in the thread due to cooling emulsion, ••Molded part stresses

Figure 237, PC glass slide (M = 1 : 1) with media cracks. The cracks only appeared in the internal thread area M10 because the highest tensions acted there due to machining during thread cutting. The also-machined (turned) outer surface was however significantly lower stressed. The cause of damage was obviously the cooling emulsion used for turning and threading. This is also confirmed by the client after a successful exchange of the cooling emulsion (see also → molded part stresses).

Figure 238

Figures & Text

••Isochromatics in a good part, ••Comparison (molded part with little isochromatics), ••Molded part stresses, low, ••Good part

Figure 238, SAN mixing cup bottom (M = 18, DL-POL). The good part showed very weak isochromatics in crossed polarizers (color lines of the same color), and after 10 min of immersion in toluene/ n -propanol 1 : 5, no microcracks developed. Therefore, the internal stresses in the bottom of the mixing cup were very small. Molded part stresses are unavoidable but, depending on the processing parameters, can be weaker or stronger (see also Fig. 239).

264



Figure 239 ••Isochromatics in a bad part, comparison (molded part with many isochromatics), ••Molded part stresses, stronger, ••Microcracks, ••Damaged part

Figure 239, SAN mixing cup bottom (M = 18, DL-POL), damaged part, detail from Fig. 238 with microcracks, weld line structures, and isochromatics. The damaged part showed much stronger stresses and microcracks in crossed polarizers after 10 min of immersion in toluene/n-propanol 1 : 5. The isochromatics (color lines of the same color) were also a little stronger. The cause of damages are external and internal stresses during injection molding (see also → injection molding).

Figure 240

Figures & Text

••Residue, grease residue white, ••Impact assessment

Figure 240, PBTP GF20 window regulator (M = 20, AL) with white grease residue. Such residue can cause stress cracks. Therefore, lubricating oils and greases used are always tested in immersion experiments (impact assessment) for compatibility with the molded part. The sample is wetted with the medium, or rather immersed, and stored for about 48 h at elevated temperature between 60 and 100 °C depending on the type of plastic and application temperature. After the removal and cleaning it is stored overnight and then examined for cracks (see also → residue and → impact assessment).

265



Figure 241 ••Diffusion of demolding agents, ••Damage reenactment, ••Release agent residue, ••Comparative examination, ••Compatibility testing

Figure 241, ASB TV back panel (M = 10, AL-DF) with white spots. According to the client, these spots occurred about 14 days after the injection molding and painting. The examination revealed that the drop-like, white spots apparently followed gravity and accumulated at the bottom edge of the television back panel. Cause was a diffused demolding agent (release agent) that was previously not cleaned and diffused into the surface. The proof was made through a damage reenactment with the paint and the chemicals used for demolding, cleaning, and thinning, which were provided by the customer. Here, the demolding agent, which was washed with thinner, accumulated at the lowest edge and led to the same white, teardrop-shaped spots after 14 days (see also → damage reenactment).

Figure 242

Figures & Text

••Long-term cracks, flexing, ••Overloading, mechanical, ••Vacuole, none, ••Flexing in POM with overheating, ••Decomposition, chemical

Figure 242, POM heavy-duty roller under water (M = 12, AL). High mechanical overload of the heavy-duty roller under water began by flexing and lead to internal heating and long-term cracks. Thus formaldehyde was released at about 60 °C. Through the water, which penetrates through the long-term cracks, the formaldehyde, which is included in the polyoxymethylene POM, oxidized to formic acid. This organic acid, a strong solvent for POM, split inside the ether bonds of the polymer chains and produced a cavity because the decomposition products were rinsed with the invading water. The heavy roller broke because of the reduced cross-section (cavity). Because the cavity is formed by a chemical decomposition and is not a shrinkage cavity, it should not be confused with a vacuole (see → vacuoles and blowholes).

266



Figure 243 ••Copper attack on PP by contact with brass, ••Cracks due to media attack, ••Damaged part

Figure 243, PP compressed air hose (M = 6, AL). The damaged part shows a very limited media attack on the outer surface of the pipe, which resulted in a bursting of the compressed air hose at pressure amplitude. The cracks are 2.5 mm deep and the conspicuous media attack in the damaged area happened due to continuous contact with an 80 °C warm brass screw connection on a radiator. Here, the polypropylene compressed hose was strongly attacked and decomposed by the copper Cu that is included in the brass screw connection (see also → copper attack and → media attack).

Figure 244

Figures & Text

••Migration, ••Plasticizer migration generates significant swelling

Figure 244, C-PVC water pipe (M = 1 : 1). A plasticizer migration from the blue tube cuff generates a significant swelling of the original smooth tube in the contact area of the C-PVC pipe surface. The significant swelling caused by plasticizer absorption led to weakening and eventually to a fracture of the water pipe with severe water damage. C-PVC is a post-chlorinated polyvinyl chloride (see also → migration).

267



Figure 245 ••Media attack by incompatible inhibitor additive, ••Media cracks, ••Microcracks, ••Cracks, axial cracks

Figure 245, PB heating pipe (M = 20, AL) with cracks. For protection against oxygen diffusion, an inhibitor was added to the water in the heating pipe. The microscopic examination revealed axial cracks on the inside of the pipe. These cracks are media cracks. Proof of this is the many microcracks found, after a bisection of the heating pipe, over a length of 5 m. A 10 µm thin section showed more or less deep cracks and microcracks up to just below the outside of the pipe, but no inhomogeneities. The cause of damage was therefore an inhibitor additive for oxygen binding in the heating water that is incompatible with polybutene PB (see also → thin section and → inhibitors).

Figures & Text

Figure 246 ••Media attack on POM by formic acid, ••Breakage of the ether bonds in POM

Figure 246, POM cover, 120 mm ∅ (M = 1 : 1) with a very strong media attack by formic acid (organic acid). Formic acid is a strong solvent for polyoxymethylene POM. It breaks the ether bonds of the polymer chains, causing the unusually large, jagged cavity to form (see also → solvents for plastics).

268



Figure 247 ••Media attack, ••Medium stain with high edge

Figure 247, CA surface (M = 23, AL). An unknown medium, which dripped onto the cellulose acetate surface, caused a slightly swollen medium stain with raised edge areas (arrows). This image is an example of a media attack. The customer wanted to know what the spot was and ask for only one photo, without further examination (see also → media attack).

Figures & Text

Figure 248 ••Copper attack, ••Media attack due to copper, ••Contaminations during installation

Figure 248, PP-R fitting (M = 28, AL) with a point-shaped media attack due to copper shavings. In such an error image, a copper attack should first be considered. Copper Cu attacks polypropylene PP. The harmful copper shavings came into the pipeline when installing the water line in the house or wetting fitting from the water lines. We recommended preventing this in the future with a superior fine filter. PP-R is a polypropylene random copolymer (see also → media attack and → copper attack).

269



Figure 249 ••Disassembly is important for damage identification, ••Media halos due to cutting oil, ••Compatibility test

Figure 249, PVC window shutter (M = 1 : 1) with threaded bore holes. After disassembly of the metal fitting, swollen media halos around the threaded bore holes (arrows) occur on the laminated surface of the PVC folding shutter. Cause was, as confirmed by the customer, that the cutting oil used for thread cutting was not tested for suitability. This also let the laminating film swell (see also → impact assessment).

Figure 250

Figures & Text

••Wetting test with test pins, ••Wettability of ABS, ••Adhesive strip test, ••Test pins to test the wettability

Figure 250, ABS dividing wall connector (M = 1 : 1), damaged part. In use, this “gold plating,” an Al-layer (deposition layer) with a yellow, transparent top coat on the surface, peeled off. To examine the cause of the damage, strip-like areas of the gold Al-layer were peeled off with an adhesive strip test. On the thus-exposed ABS surface, a wetting test with different wetting liquids (test pins) then yielded a low wettability of 30 mN/m, instead of 34 mN/m. Cause of damage was therefore an insufficiently pretreated ABS plastic surface (ABS is acrylonitrile butadiene styrene copolymer; see also → wetting test and → adhesive strip test).

270



Figure 251 ••Copper in the flow direction in front of PE-X destroys the matrix, ••Copper attack in a PE-X pipe, ••Copper ions, ••Matrix crosslinking destroyed

Figure 251, PE-X pipe (M = 18, AL), damaged part with extraordinarily badly damaged inner surface of the pipe. This was caused by an attack by copper Cu. In the flow direction was a copper pipe before the beam crosslinked polyethylene water pipe. During the water flow, copper ions that dissolved reached into the PE-X pipe and destroyed the crosslinked matrix. Copper attacks polyethylene PE and polypropylene PP (see also → media attack and → copper attack).

Figure 252

Figures & Text

••Weld line with axial cracks, ••Molded part stresses, high, core displacement, ••Mass flows with parallel cracks, ••Parallel cracks in fingerprints, ••Inclined cracks

Fingerprints

Figure 252, PP glass dome (M = 1 : 1), damage overview with an axial crack (from 1 to 1), long inclined cracks (2), and many parallel cracks (3) in the round fingerprints. The long inclined cracks followed the flow fronts in the mold filling, and the axial crack originated in the weld line between two mass flows due to a core displacement and high molded part stresses. The injection was done centrally in the mold part bottom (right). The cause of damage was, in addition to media loads (cracks) in the area of fingerprints, a too-high injection pressure that changed the filler cross-sections due to a core displacement, and thus, produced mass flows that were flowing at different rates. The fingerprints with the parallel cracks can be explained by dirty fingers, which were contaminated with a PP-damaging medium, even if that seems incredible.

271



Figure 253 ••Fluorination of PA6 GF30, ••Ejector marking, ••Media resistance by fluorination

Figure 253, PA6 GF30 gear wheel for a car fuel tank cap (M = 6, AL) with a fluorination of the surface to increase the media resistance to gasoline and diesel fuel. The gear wheel has a significant ejector marking (blue arrows) and a cold-flow area close to the gate (see also Fig. 254).

Figure 254

Figures & Text

••Fluorination of PA6 GF30, ••Demolding pins, worn, ••Erosion of the molded part surface, ••Glass fibers in the surface

Figure 254, PA6 GF30 gear wheel for a car fuel tank cap (M = 25, AL), detail from Fig. 253 with the surface fluorination. The fluorination should make the gear wheel surface chemically more resistant to gasoline and diesels. In the examination, a protruding burr (arrow 1) and a strong erosion of the molded part surface (arrow 2) with exposed glass fibers in the surface were found, particularly in the area of ejector pins (see Fig. 253). The causes of damage were a little too-early molded part demolding (deeply incised ejection pins) and cold processing during injection molding with molded part stresses and a strong attack (erosion) by fluorination.

272



Figure 255 ••Copper attack in a PP liner, ••Liner with cracks, ••Transverse cracks, unusual, ••Cracks perpendicular to the extrusion

Figure 255, PP-R/Al/PP-R drinking water pipe, diameter 20 mm (M = 8, AL). The liner on the inside of the pipe has unusual transverse cracks perpendicular to the extrusion direction. The brown deposit is rust, and the cause of damage by the cracks was a Cu attack by copper particles. PP-R/Al/PP-R is a polypropylene random copolymer with Al layer (see Figs. 256 to 258).

Figure 256

Figures & Text

••Copper attack in a PP liner, ••Liner with cracks, ••Oxygen diffusion barrier, ••Layer structure (composite pipe)

Figure 256, PP-R/Al/PP-R drinking water pipe, diameter 20 mm (M = 12, AL). A polished sample through the pipe cross-section of Fig. 255 shows three layers: a top layer (1), an aluminum layer Al (2) as an oxygen diffusion barrier, and an liner (3) with destroyed, greenish polymer structure, such as is typical for a Cu attack in olefins (PE, PB, PP) (see Figs. 255, 257, and 258).

273



Figure 257 ••Copper attack in a PP liner, ••Fracture edge with fracture center, ••Copper attack generated halo-like matrix cracks, ••Crack structure, branching

Damage center Figure 257, PP-R/Al/PP-R drinking water pipe, diameter 20 mm (M = 31, AL), detail from Fig. 256. A crack, which is broken away by hand, shows a branching crack structure on the broken edge, which starts at the damage center of incoming damage, with a green halo up to half of the liner wall thickness (see Figs. 255, 256, and 258).

Figure 258

Figures & Text

Al-layer

Figure 258, PP-R/Al/PP-R drinking water pipe, diameter 20 mm (M = 12, AL), with an exposed aluminum layer. The Al outer layer is deformed throughout the transverse cracks (arrows) because the liner, which is receiving pressure, was leaking (see Fig. 257), and the penetrating water built up pressure under the aluminum layer. There, the area corroded and a leak developed in the drinking water pipe because the thin outer layer of the pipe failed (see also Figs. 255 to 257).

274

••Copper attack in a PP liner, ••Al-layer is corroded after the copper attack of the liner and has transverse cracks



Figure 259 ••Atomic absorption measures Cu content, verdigris, ••Liner with cracks, ••Copper attack in EPDM liner, ••Copper ions

Compression connection

Verdigris

Figure 259, PVC cold water mesh tube with crosslinked EPDM liner (M = 30, AL). The EPDM liner had cracks, particularly in the transition of the crimped connection (red arrows) and a greenish coating. There a leak developed. Atomic absorption showed a high percentage of copper in the damage area (inside liner) and a barely detectable copper content on the still-intact outside of the liner. A visual indication of copper Cu was also the greenish coating, recognized as verdigris. The causes for such damage were copper ions from brass and red brass connectors (fittings), copper pipes, or copper-bearing distributors in flow direction in front of the area of damage. EPDM is an ethylene propylene tar copolymer.

Figure 260 ••Fuchsine dispersion, ••Contrast enhancement with fuchsine, ••Tension cracks through media

Figures & Text Figure 260, PA door handle (M = 22, AL) with tension cracks due to media influences by the public, such as hand sweat, hand cream, or perfume remains. A UV load due to solar radiation could be excluded in the office space. For better recognition and enhancement of the contrast, the cracks were stained with fuchsine. Fuchsine, a red pigment powder, is dissolved in water, or better in alcohol (if compatible with plastic), and is then applied with a cloth. The excess is immediately wiped off. The fuchsine dispersion penetrates quickly into the smallest capillary cracks and makes them more visible (see also → coloring).

275



Figure 261 ••Molded part stresses under the paint, ••Paint defect?, ••Cracks in the paint film

Figure 261, PC ventilation grilles (M = 50, DL). The client asked for an examination for the cause of fracture. A 10 µm thin section through the damaged area showed long cracks under the paint layer, deep into the molded part surface. After peeling the paint with a solvent, a wave structure was visible above the cracks, which was recognized as an orange skin, which occurs at too-cold processing, The too-cold processing explained the high stress level in the molded part surface that caused the long cracks through the solvent content in the paint. A paint defect, as suggested by the client, was not present (see also → molded part stresses, → painting error, → orange skin, and → processing, cold).

Figure 262

Figures & Text

••Effect paint (Al-effect paint), ••Molded part stresses, ••Solvent penetration depth, ••Solvent effect generated tension cracks, ••Tempering

Figure 262, PA/PE hub cap, polymer blend, painted (M = 50, DL). The hub cap was painted with solvent-containing aluminum-effect paint. In an 8 µm thin section through the layer structure (hub cap/Al-effect paint) the solvent influence was visible as a bright area under the paint. The solvent penetration triggered many tension cracks in the injection-molded hub cap. Possible remedies include increasing mold temperature, tempering the hub cap, or reducing solvent content in the Al-effect paint.

276


LM Subchapter: Metal abrasion

Figure 263 ••Metal or plastic particles?

Figure 263, PP hot runner pinpoint gate (M = 25, AL) with shiny metal particles and brown burn marks, which are concentrically distributed around the gate (see Fig. 264).

Figure 264 ••Metal or plastic particles?, ••Friction in the hot runner pinpoint gate, ••Burn marks in the gate

Figures & Text Figure 264, PP hot runner pinpoint gate (M = 28, AL), detail from Fig. 263. It has been suggested that the shiny particles (arrow) are metal particles. The microscopic examination revealed up to 1300 µm long, brown streaks with black burned areas. Cause of damage was a too-high injection speed. This caused a friction (local overheating through excessive friction). Whether the shiny particles were a metal abrasion from the screw or the cylinder or metallic impurity (chips) from the outside could not be microscopically reliably detected. Only after isolation of the particles was a further examination with a magnet possible. Because the magnet attracted them, they were metal particles. Other specification options could include trials with solvents, melting experiments on a melting table, or thermal analysis.

277


LM Subchapter: Metallization

Figure 265 ••Electroplating error with bubbles, ••Bubbles, sharp-edged,

Figure 265, ABS blend, matte nickel-plated (M = 6, AL). The blend has sharp-edged bubbles on the visible side in the nickel layer. More information is given in Figs. 266 to 268.

Figure 266

Figures & Text

••Electroplating error with bubbles, ••Bath contamination through media, ••Bubbles sharp-edged, ••Electroplated layers, ••Residue on the palladium coating

Figure 266, ABS blend, matte nickel-plated (M = 25, AL). After opening the bubbles showed (in Fig. 265), showed a barely visible deposition (residue) on the palladium layer. For comparison, examined injection-fresh good parts had a porous, smooth, high-gloss molded part surface without residues (mold release agents, grease, fingerprints, or oil). For electroplating, a palladium-guiding layer application followed after the cleaning bath, then the copper and matte nickel layer. Damage causes for the bubbles: Countless black spots, up to 50 µm big (Fig. 267) dried on the galvanized matte nickel surface. With an ESCA analysis, contamination by the elements C, K, P, Cl, Na, and S can be found in flower-like surface defects (in Fig. 268). The barely visible deposit on the palladium layer was not examined in detail. In our opinion there is a bath contamination that caused the bubbles between the control and copper layer (see also Figs. 265 to 268 and → residue).

278



Figure 267 ••Electroplating error with bubbles, ••Bath contamination, ••Spots, black

Figure 267, ABS blend, matte nickel-plated (M = 200, AL), detail from the surface in Fig. 266. On the electroplated matte nickel surface are countless dried-on black spots, which are up to 50 µm. These are bath contaminations, such as those that sometimes occur in aged bath methods (see Figs. 265 to 268).

Figure 268 ••Electroplating error with bubbles, ••Element determination with ESCA analysis, ••Salt flower on a nickel layer

Figures & Text Figure 268, ABS blend, matte nickel-plated (M = 400, AL). The flower-like surface defects developed through nickel-plating due to dried-on salt compounds. ESCA analysis (electron spectroscopy for chemical analysis) with a PHI spectrometer 5500 showed the cause of the contamination, the elements C, K, P, Cl, Na, and S (see Fig. 265 to 267 and → ESCA analysis).

279



Figure 269 ••Bath carryover during electroplating, ••Weld line with air induction, ••Electroplating errors, ••Electroplating layers (palladium, Cu, and Cr), ••Injection molding error

Figure 269, PP base plate (M = 31, DL-POL). The base plate had peeled electroplated layers upon delivery (copper Cu, nickel Ni, and chromium Cr). The microscopic examination on a 10 µm thin section showed an open weld line in the molding surface caused by a too-cold processing during injection molding. The damage causes of the peeled electroplated layers were open weld lines with air induction, too-cold processing, and liquid carryover in the weld line from the cleaning bath before the application of the Cu layer.

Figure 270

Figures & Text

••Electroplating error with bubble formation, ••Delamination, ••Bubble is opened with a scalpel, ••Preparation of the bubble with a scalpel cut, ••Injection molding error

Figure 270, POM door handle (M = 25, AL) injection-molded article with sharp-edged bubble in the chrome layer. Because electroplating layers are very hard, the small electroplating bubble had to be broken up forcefully with a scalpel (cutting was impossible). Other tools were unsuitable because they slipped on the rising bubble edge. The scalpel blade slipped a lot until it jammed in a developed scratch. To grind the bubble open would certainly have been more elegant, but would have led to contamination and thus to a possible misinterpretation of the error. The opened bladder showed a residue-free cavity (without contaminations) but with film-like detachments on the plastic surface (see Fig. 271 and → delaminations).

280



Figure 271 ••Electroplating error with bubble formation, ••Electroplating bubble with a sharp-edged bubble always arises with the first metal layer, ••Electroplated layers are brittle and hard, ••Injection-molding errors

Figure 271, POM door handle (M = 31, AL). The figure shows an electroplating bubble that is opened with a scalpel (arrow), and after removal of the metal layers, and is also a delaminated surface (delamination). The damage was caused by the injection molder. Explanation: Through the vapor pressure of a diffused bath liquid into the film-like separation (see also Fig. 270), a plastic bladder originated prior to the copper plating, which was covered with a nickel and chromium layer in the subsequent baths. Since the electroplating layers are brittle and hard, they cannot subsequently bulge to sharp-edged bubbles. High bulged bubbles with a sharp edge blister therefore always developed at the beginning of the first metal layer. With poor adhesion, very flat, bubble-like detachments of the metal layers are possible. Such separations do not have any sharp bubble edges (see Fig. 272, → delamination, and → electroplating error).

Figure 272

Figures & Text

••Electroplating error due to a molded part error, ••Illumination with oblique incident light, ••Electroplated layers were removed, ••Injection molding errors

Gate

Figure 272, ABS/PC sleeve, nickel-plated, (M = 10, AL, diagonally inferior). The picture shows the state after removal of the electroplated layers palladium, Cu, Ni, and Cr with 25% HCl (3 min at 30 °C) or 40% HCl (1 min at 65 °C). Causes of damage: A 10 µm thin section through the injection-molded sleeve shows barely recognizable, bubble-like delamination layers in the gate area that have emerged after electroplating. There, chemicals have invaded, for example demolding and or cleaning agents from injection molding or chemicals from electroplating baths. Thus the bubbles were created during electroplating. This happens preferably in weak areas, such as weld lines and cold-flow areas. The injection molder was to blame for the damage (see also → electroplating error).

281



Figure 273 Flow structures

Bubble

••Electroplating error due to molded part defects, ••Illumination with oblique incident light, ••Bubbles in the plastic surface after removal of the electroplating layers and flow structures, ••Injection molding errors

Bubble

Figure 273, SB housing, nickel-plated, electroplating error (diagonal = 10 V, AL, inferior) due to molded part errors. The electroplated housing surface had bubbles and unwanted structures (cold-flow areas or air streaks). The causes of damage were only found after peeling the electroplated layers in the exposed plastic surface. Cause of the bubbles on the electroplated SB housing (arrows) was protracted and adhesive plastic particles in the mold from the previous filling process. The unwanted structures are floating structures due to a lack of mold filling. Only at a deep illumination did the plastic particles and unwanted structures become clearly visible (see also Fig. 272).

Figures & Text

Figure 274 ••Electroplating error due to molded part defects, ••Weld line, close to the gate, ••Damage cause and assignment of guilt, ••Injection-molding error

Weld line

Figure 274, PA6.6 bracket, electroplating error due to molded part defects (M = 31, AL). In the electroplated bracket close to the gate, flow-like lines (blue arrows) and bubbles (red arrows) become apparent in the chromium layer. To investigate the dispute, the electroplated layers palladium, copper Cu, nickel Ni, and chromium Cr were replaced. It became clear that it was not an electroplating error but an injection-molding error that was present, and therefore the blame was with the injection molder (client). A further investigation was not required.

282



Figure 275 ••Electroplating errors, ••Bubble series in electroplating layer, ••Electroplating bubbles with sharp bubble edge

Figure 275, ABS blend (M = 10, AL) with an electroplating error. The blend had a partial, approximately 8 mm long, sharp-edged bubble series in the electroplating layer on the outside, but only at one single point. No residues were found in open bubbles. The molded part surface and the comparative samples were flawless. Cause of damage: The only certainty is that the bubbles were created during the construction of the conductive layer and copper layer. Everything else is conjecture if a gaseous medium has disappeared without leaving a residue, and no molded part defect is present. After such a mistake, some electroplaters say spontaneously that the molded part has too-high residual moisture and it was the molder’s fault. At high moisture content (predrying missing), bubbles developed on the entire molded part surface and not just in a single spot because the residual moisture diffused over the whole surface. Incidentally, high residual moisture could have originated in the molded part in the electroplating baths (see also → electroplating error, → residual moisture, and → predrying).

Figures & Text

Figure 276 ••Electroplating errors, ••Electroplating bubble, with sharp-edged bubble

Bubble

Figure 276 ABS grip shell (M = 8, AL). Sample 1 from cavity 2 shows an electroplating error. On the inner side of the blend, a large, strikingly sharp-edged bubble is located in the area of the mold cavity number in the electroplating layer. The bubbles developed in the vertically hung molded parts always in the “lower blend part,” because a liquid (from the cleaning), which is following gravity, diffused in during dripping and diffused out again through the influence of temperature in the electroplating bath. Because the damage only occurred at the “lower blend range,” a systematic error was present. The cause of damage was a medium that was transferred during the pretreatment and then outgassed in the copper bath (see also Fig. 277 and → electroplating error).

283



Figure 277 ••Electroplating error, ••Electroplating shadows due to too-dense suspension, ••Palladium conductive layer

Conducting layer Figure 277, ABS grip shell (M = 31, AL), sample 2 from the mold cavity 2 also shows an electroplating error. The conspicuous sharp-edged bubble on the inside of sample 1 (Fig. 276) was missing in the cavity area of sample 2, as well as the electroplating layers. Only the palladium conductive layer was present. Also noticeable was the strange oblique shadow on number 2. It may have originated from the illumination when taking pictures. Cause of damage was, in our opinion, too tight or inappropriate mounting of the blend in the bath. The thereby developed “galvanizing shadow” hindered the formation of the layers, and thus the blame for the damage can be found with the electroplater (see also Fig. 276).

Figures & Text

Figure 278 ••Aluminum vapor deposition of PE, ••Electrostatic charge due to friction, ••Impurities in vapor chamber

Figure 278, PE ventilation grille, Al-vaporized and painted with a PMMA topcoat (M = 200, AL-DIC + -plate). The examination revealed the damage causes: unwanted plastic deposits of PE and dirt on the surface before the vapor deposition with aluminum Al and painting. They were probably caused by an electrostatic charge and mutual friction in handling. Our customers subsequently confirmed (on the phone) too-little humidity and friction of PE ventilation grilles in production and transportation as well as impurities in the vapor chamber.

284


LM Subchapter: Particle

Figure 279 ••Coal particles without matrix bonding, ••Cross-sectional weakening

Figure 279, PA piston ring film, damaged part (M = 50, DL-POL + -plate). A 10 µm thin section through the piston ring film shows partially touching coal particles and a poor matrix bonding. Under stress, the poor integration of the coal particles led to breakage through cross-sectional weakening. Also the plastic did not have sufficient affinity (“bonding strength”) to the surface of the carbon particles. This should improve the sliding properties between a piston and a cylinder, but they acted like disturbed foreign particles. For a better matrix bonding, we recommended a reduction of the carbon particles and a higher mold temperature.

Figures & Text

Figure 280 ••Residual granulate with poor matrix bonding, ••Screw speed is too low, ••Jacket heating is too low

Particle

Figure 280, PE cable protection pipe (M = 18, AL). The cable protection pipe has a protruding, black particle with poor matrix bonding in the fracture flank. A 10 µm thin section in the damaged area shows black carbon black streaks (no picture). As further thermal analyses (IR and DSC analyses) revealed, the black particle was an unmelted residual granulate due to the homogenization time, which was too short. Such damage could have also caused a too-low temperature yield of the jacket heating or a too-low screw speed.

285



Figure 281 ••Fracture center PVC-U with foreign particles, ••Foreign particles, ••Costs by avoiding unnecessary examinations, ••Clarify the question of guilt

Foreign particle

Figure 281, PVC-U drinking water pipe (M = 50, AL-DF), damaged part. To clarify the question of guilt, a microscopic examination was done. Thereby many smooth crack areas with black foreign particles that were up to 1.90 mm long, were found in many different pipe cross-sections (1 = tube interior, 2 = tube exterior). The fracture areas were deliberately extended by hand, and then the fracture flanks were examined. Here some of the unwanted foreign particles fell out of the fracture areas. The finding that the damage was caused by a contaminated molding compound was enough and showed the customer the imperfect pipe manufacturing. Therefore, the pipe manufacturer was to blame for the high water damage and not the client (installer). Further studies have been avoided, thereby saving unnecessary costs for them.

Figure 282

Figures & Text

••Electroplated layer residues, ••Good part, apparent, ••Leakage current through metal particles, ••Metal particles in the surface

Figure 282, POM GF30 electric switch (M = 50, AL), damaged part with metal particles in the plastic surface. They are peelings of the electroplating layer of injected metal contact points. The metal particles are partially heaped and layered, whereas the underlying ones are melted in the surface. The upper, wipeable metal particles could therefore detach and cause electrical interference due to leakage currents in the reed area. The previous parts, which were sold as good parts, and the electrical switches included for comparison were apparently good parts. They had only a few or better integrated metal shavings.

286



Figure 283 ••Particle, film-like, in the area of needle shut-off nozzle

Particle

Figure 283, PS plate (M = 6, AL). The direct gate has film-like particles in the area of the used shut-off nozzle (arrow). As a remedy, it was recommended to the customer that the shut-off nozzle, which is worn from long use, should be replaced, or, if not, possibly reworked so that no burrs will form through the molding compound and be carried off into the molded part (see Fig. 284).

Figure 284 ••Particle, film-like, in the molded part, ••Needle shut-off valve, leaky, replace

Figures & Text Figure 284, PS plate (M = 20, DL-POL + ) from cavity 4. The film-like particles on the direct gate in Fig. 283 are carried off into different mold cavity gates during injection (cavities) and there, led to optical defects, especially in the plate from the mold cavity 4. The colorful areas are caused by light refraction in polarized transmitted light with lambda plate (see also → lambda plate and → contrast methods in microscopy).

287



Figure 285 ••Particles black, burnt, with increased melting temperature

Figure 285, PA6.6 sealing cap (M = 25, AL), damaged part with foreign particles. The black burned foreign particle, which is enclosed in the molded part surface, is 2325 µm long. It was isolated with a scalpel and a dissecting needle and further examined by means of IR and MFR analyses, but could not be clearly identified. Its sharpness on the edge proves a higher melting temperature than that of the matrix. The cause of the fracture of the sealing cap was the sharp-edged foreign particle because it acted as a weakening area in the cross-section (see also → foreign particles, → IR analysis, and → MFR analysis).

Figure 286

Figures & Text

••Foreign particles below the surface of the molded part, ••Illumination with low incident light

Figure 286, PP plate (M = 50, AL-DF) with dark, 2.15 mm long foreign particles densely located below the surface of the molded part. Such particles are especially visible in the incident light-dark field AL-DF. A foreign particle contains another material (dirt, sand, metal, and so on) or foreign molding compound and is often harder to melt than the matrix, or is even impossible to melt (see also → foreign particle, → matrix, and → contrast methods in microscopy).

288


LM Subchapters: Particle

Figure 287 ••Carbon black conglomerate with crack, ••Homogenization, poor, ••Carbon black type, not suitable, ••Approval of a roofing sheet

Figure 287, PE roofing sheet (M = 30 DL). A 10 µm thin section shows a 52 µm carbon black conglomerate with a crack due to the cutting force during cutting and is hangs barely onto a vacuole. Carbon black conglomerates form during an insufficient homogenization or by using an inappropriate type of carbon black. The approval of the roofing sheet could not be granted because only a maximum of 30 µm large carbon black conglomerate was allowed.

Figure 288

Figures & Text

••Foreign particles, transparent

Foreign material Figure 288, PP/PE molded part, polymer blend (M = 30, AL-DF). An unmelted, highly transparent foreign particle is present in the fracture surface of the damaged part (see also Fig. 289).

289



Figure 289 ••Foreign particles, transparent, ••Examined IR and DSC analyses, ••PP/PE polymer blend

Figures & Text

Figure 289, PP/PE-molded part, polymer blend (M = 15, AL-DF), detail from Fig. 288, but from a different area of the molded part surface. A transparent foreign particle protrudes (arrows 2) from the punctured plastic surface (arrow 1). The transparent foreign particles and other foreign particles found in the surface were removed and identified by IR and DSC analyses as heavy melting PMMA residues.

Figure 290 ••Molding compound, burned, ••Conglomerate

Figure 290, PB pipe (M = 50, DL), damaged part. A 10 µm thin section shows an 1150 µm large conglomerate in and below the surface of the pipe. Studies of the isolated conglomerate and more from other areas showed by means of IR and DSC analyses that burned polybutene molding compound is present (see also → IR analyses and → DSC analyses).

290



Figure 291 ••Cold plug, ••Orange skin, ••Particle, unmelted, ••Pipe manufacturing, too fast

Figure 291, PE pipe inside (M = 31, AL). During extrusion, a 2.26 mm long particle was flushed to the pipe surface. It was incompletely melted and could therefore not properly “weld” to the matrix (molding compound). As DSC and MFR analyses on the extracted particle showed, it was identical to the molding composition of the PE pipe and thus was a cold plug (no foreign material). The pipe was leaking due to cross-sectional weakening of the particle and of the pressure load in use. In addition, orange skin was detected on the pipe surface. Causes of damage were therefore the cold plug and the orange skin due to an insufficient molding compound temperature and homogenization, as happens at a too-fast throughput (during rapid production of pipes).

Figures & Text

Figure 292 ••Foreign particles, ••Particle, unmelted, ••Illumination with low incident light, ••Error due to particle inclusion

Figure 292, PVC drinking water pipe (M = 18, AL), damaged part. In the pipe surface, there was a partially unmelted black particle with poor matrix bonding. The error was only clearly visible in oblique incident light. The PVC pipe is gray, the particles black and unmelted. This points to a foreign particle without further investigation. The pipe broke at the weakened imperfection, where a single lever tap allowed for the quick stop of water.

291



Figure 293 ••Dispersion, poor, ••Carbon black conglomerate, very large, ••Masterbatch confusion, ••Carbon black, not homogenizable

Figure 293, PE drinking water pipe (M = 25, DL), 10 µm thin section with an about 2015 µm long carbon black conglomerate. Such a large carbon black conglomerate indicated a poor homogenization. Here, a difficult to disperse or not dispersible at all type of carbon black was processed. Carbon black conglomerate of more than 100 µm in diameter can also be found in the granulate. Cause of damage in the subsequent coloring of the PE molding compound was a masterbatch mixed with an inappropriate type of carbon black. Carbon black conglomerate of this size can develop in rare cases, in addition to masterbatch confusion, when the masterbatch manufacturer had used a cheaper (for cost reasons) type of carbon black or an inappropriate masterbatch carrier.

Figure 294

Figures & Text

••Dispersion, poor, ••Molding compound areas, uncolored, ••Homogenization poor?, ••Carbon black conglomerate to 100 µm, ••Carbon black type is not homogenizable

Figure 294, PE drinking water pipe (M = 25, DL) with an extremely large pigment conglomerate of more than 100 µm in diameter and white flow lines (uncolored molding compound). In the subsequent coloring, a masterbatch was obviously used with an unsuitable type of carbon black, which was not dispersible, even with the best homogenization. The white flow lines developed due to insufficient dispersion of the carbon black, which is included in the masterbatch, and not as initially suspected, by poor homogenization (see also → masterbatch).

292


LM Subchapter: Fungi

Figure 295 ••Fungus growth due to plasticizer influence

Figure 295, PC fiber optics channel (M = 100, DF-AL) with deposits and fungal growth due to plasticizer migration from the PVC cable sheathing of the electrical cable in the fiber optics laid channel. For such examinations, the dark-field reflected light DF-AL is particularly suitable.

Figure 296 ••Mouth and throat flora due to eating habits, ••Fungi, ingrown, in silicone, ••Leakage caused by fungi

Figures & Text Figure 296, Silicone vocal valve (M = 6, AL). A silicone vocal valve is used in laryngeal cancer cases so that no liquid and food passes into the lungs when swallowing. Depending on eating habits, unfavorable oral flora and deposits from the patient formed on the valve-closing surfaces and the vocal valve sometimes leaked after only one year. In this case, fungi (Candida glabrata, Candida Torulopsis, Candida albicans) grew on the surface (see also Figs. 365 to 367).

293


LM Subchapter: Fungi

Figure 297 ••Fungi on teakwood, yellow,

Figure 297, Teakwood bench (M = 31, AL). After 15 years of outdoor exposure in the Würzburg climate, areas with yellow fungi, of a type that is unknown to us, developed on the surface of the teakwood bench.

Figure 298

Figures & Text

••Earth pressure deformation with axial crack, ••Mycels, ••Hyphae, white, ••Water contamination

Figure 298, HDPE drinking water pipe 50 × 4 (M = 30, AL). The pipe was buried in the ground for a long time. A stone in the sand bed and the earth’s pressure deformed the pipe and thereby generated a long axial crack. When it was opened during preparation, a crack edge showed an initiation area with brown staining (arrows) that had been developing for some time. From there, thin, white hyphae grew (mycels) from the outside to the inside of the pipe. That means that contamination, fungi, microbes, and possibly chemicals could enter the drinking water through the leaking axial crack.

294


LM Subchapter: Marginal zone

Figure 299 ••Marginal zone, extremely low in spherulites, ••Lack of holding pressure, ••Vacuoles, ••Mold temperature, cold,

Figure 299, POM housing with bar (M = 8, DL-POL + -plate). A 10 micron thin section under polarized light with a lambda plate shows pronounced border zones that are low in spherulites and up to 500 micron, as well as vacuoles. The spherulite-poor marginal zones developed due to a too-cold mold temperature and the vacuoles due to a lack of holding pressure. Cold marginal zones are only in semicrystalline polymers, visible as marginal zones that are low in spherulites. In amorphous polymers, marginal zones also occur as in semicrystalline plastics, but they are usually not visible. However, an intentional violent fracture in amorphous and hard plastics often shows a fracture edge crack with about 45° or a boundary layer separation. In the present case, the damage causes were a frozen pinpoint gate and a no-longer effective holding pressure (see also Fig. 300, → plastic materials, → lack of holding pressure, and → marginal zone, poor in spherulites).

Figure 300

Figures & Text

••Core, plastic (center of the wall), ••Embrittlement through a marginal zone that is extremely low in spherulites

Figure 300, POM housing with bar (M = 8, DL-POL + -plate), details from Fig. 299 but in a different area. The large spherulites grew in the plastic core (center of the wall) because the mass temperature acted there for a long time and was high enough for the spherulite growth. The temperature dropped more quickly on the cold mold walls, and so marginal zones, low in spherulites, developed. Because these are prevalent, and hard and brittle, the housing fractured in use. The causes of damage were therefore the large spherulites in the center of the wall (plastic core) and the marginal zones, which are low in spherulites, due to too-cold processing (see also Fig. 299, → mass temperature, → core, plastic, → spherulite growth, and → marginal zone, poor in spherulites).

295



Figure 301 ••Gate POM, frozen ••Holding pressure, dropped too early, ••Marginal zone, low in spherulites, ••Vacuole still recognizable, ••Mold halves, unequally heated, ••Mold temperature control, unequal

Figure 301, POM locking hooks (M = 20, DL-POL + -plate), 10 micron thin section. The unequal marginal zones, which are low in spherulites, developed from unequally heated mold halves, and a vacuole outside the bottom edge of the figure developed due to an ineffective holding pressure because the gate froze in the cold, left mold half. The higher temperature of the right mold half (shown on the right) and significantly lower temperature of the left mold half are clearly recognizable. Therefore, the influence of the thicker spherulite-poor marginal zone caused a brittleness that was the cause of fracture of the locking hook.

Figure 302

Figures & Text

••Marginal zone, low in spherulites, caused embrittlement

Figure 302, POM trapezoidal thread (M = 15, DL-POL + -plate), 10 micron thin section in fracture area. The cause was a spherulite-poor marginal zone with a flow layer, and its brittle influence due to a too-cold mold.

296



Figure 303 ••Marginal zone, barely recognizable, ••Spherulite size, the same

Figure 303, PA molded part (M = 25, DL-POL + -plate), injection molded at 120 °C mold temperature. In the 10 micron thin section, surprisingly, no clear marginal zone that is low in spherulites is recognizable, as is usual, because nearly constant spherulites could grow throughout the molded part section due to the high mold temperature. But at the end of a turbulent mold filling, when molding material that is still hot from the molded part interior reaches into the marginal area, a similar marginal zone, poor in spherulites, may develop (see also → mass inversion).

Figure 304

Cold marginal zone

Figure 304, CP threaded nut (M = 20, AL). The threaded nut broke while tightening. The fracture surface of a thread flank shows a rare, clearly visible marginal layer (arrows) in an amorphous plastic. The thick marginal layer demonstrates the influence of a too-cold mold. The causes of damage for the fracture were a nonrounded thread transition (figure top left) near a large vacuole (outside the picture) and a mold temperature that was too low (see also → mold filling and → mold temperature).

297

Figures & Text

••Marginal zone in amorphous plastic materials, ••Transition without rounding



Figure 305 ••Marginal zone, extremely low in spherulites

Figure 305, POM torsion rod (M = 6, DL-POL + -plate). The picture shows a 10 micron thin section close to the fracture with a strongly pronounced marginal zone, which is low in spherulites, resulting from a too-low mold temperature (see also Fig. 306).

Figure 306

Figures & Text

••Gate POM, not frozen, ••Holding pressure, dropped too early, ••Vacuole is a center vacuole, ••Creep rupture line

Figure 306, POM torsion rod (M = 6, DL-POL + -plate), detail is similar to that shown in Fig. 305. After a communication to the customer that a too-cold mold caused the marginal zone, which is low in spherulites, and thus caused the fracture, they delivered a supposedly improved sample (Fig. 306), without a spherulite-poor marginal zone, but with a center vacuole. It was created by a holding pressure dropped too early. In a well-adapted mold temperature, no (or only a slightly) visible spherulite-poor marginal zone developed. Therefore, the gate could not be frozen. Rather, the holding pressure was dropped too early. The circular ring (creep rupture line) in the middle of the wall was probably created at a pressure drop between the injection pressure and holding pressure. Thus, the already frozen molding compound melted again, which produced crystalline structure changes. Such a phenomenon was often observed in old injection-molding machines.

298


SEM Subchapter: Weathering

Figure 307 ••Weathering 4800 MJ/m2 (2444 h) in the Xenon tester 1200 CPS, ••Weathering abort, ••Weathering data, ••Edge effect in SEM

Figure 307, PP-UV stabilized lounger (M = 2700, SEM). A 68 × 50 mm specimen was cut out from the lounger and weathered according to DIN EN ISO 4892-2 with the following data in a Xenon tester 1200 CPS: synchronized at Eglob = 550 W/m2 ± 10%, EUV = 60 W/m2 ± 12 W/m2, sample chamber temperature = 35 °C, relative humidity = 65 ± 5%, black standard temperature BST = 60 ± 3 °C, white standard temperature WST = 40–45 °C, cycle = 18/102, filter assembly three Suprax third shells. Cracks and microcracks formed in the surface after a radiation dose of only 4800 MJ/m2 (after 2444 h) of artificial weathering. This corresponds to only about 2.9 years of outdoor exposure in central Europe and does not meet a five-year warranty, as required. To save costs for the customer, the weathering was prematurely terminated after 2444 h, instead of after 8182 h as originally agreed. Eglob (W/m2) = global irradiance in nature at 400–800 nm; EUV (W/m2) = irradiance at 300–400 nm in the device.

Figure 308

Figures & Text

••Weathering warranty is not reached, ••Surface with insular dissolution after 3056 h weathering

Figure 308, PP-UV stabilized lounger (M = 2700, SEM). Following a telephone interim report, a 68 × 50 mm sample was cut from a supposedly better UV-stabilized lounger than the one in Fig. 307 and is weathered with a radiation dose of up to 6000 MJ/m2 in a Xenon tester 1200 CPS according to DIN EN ISO 4892-2, with the following data: synchronized at Eglob = 550 W/m2 ± 10%, EUV = 60 ± 12 W/m2, sample chamber temperature = 35 °C, relative humidity = 65 ± 5%, black standard temperature BST = 60 ± 3 °C, white standard temperature WST = 40–45 °C, cycle = 18/102, filter assembly with three Suprax third shells. The surface showed an insular dissolution of the surface after 3056 h of weathering. This corresponds to approximately 3.67 years of outdoor exposure in central Europe but still does not meet a five-year warranty, as required (see also Fig. 307).

299


SEM Subchapter: Weathering

Figure 309 ••Welding stresses, ••Brittle cracks in roof welding line after five years of outdoor exposure, ••Embrittlement in polymer roof welding line

Figure 309, Polymer welding line (M = 36, SEM). Along the fracture edge, close to the weld line of the roof welding line, many parallel brittle cracks formed in the weathered surface. Causes were released welding stresses and embrittlement of the welding line after five years of outdoor exposure in the Würzburg (Germany) climate.

Figure 310

Figures & Text

••Aging due to media influence after a year of weathering, ••Integral foam with cracks, ••UV stabilization, poor

Figure 310, PUR bumper, integral foam (M = 65, SEM), damaged part (after recall). The damaged part has a long dried-up medium streak and developed cracks after only one year of weathering in the central German climate. Too little UV design in the PUR bumper and an additional media influence (medium streak) were probably the causes of insufficient weather resistance and accelerated aging.

300


SEM Subchapter: Weathering/Fractures

Figure 311 ••Weathered surface of a cladding sheet with crystals and fibers

Figure 311, Cladding sheet, cement-bound (M = 66,000, SEM). The cladding sheet has different crystals and fibers on the weathered surface. For weathering, a 68 × 50 mm specimen was cut out and weathered in a Xenon tester beta LM to 4300 MJ/ m2 according to DIN EN ISO 4892-2 as follows: synchronized at Eglob = 550 W/m2 ± 10%, EUV = 60 ± 12 W/m2, sample chamber temperature RT = 35 °C, relative humidity = 65 ± 5%, black standard temperature BST = 60 ± 3 °C, white standard temperature WST = 40–45 °C, cycle = 18/102, equipped with three Xenochrome filter 300. The high magnification in a scanning electron microscope showed the events that would not be seen in a light microscope. For plastic examinations, only up to a 10,000-fold magnification is usually used (see also Figs. 307 and 308).

Figure 312

Figures & Text

••Crack initiation center SB, ••Foreign particle, unwanted, ••Matrix adhesion, poor, ••Tear zone

Figure 312, SB pull rod with crack initiation area (M = 340, SEM). The fracture was caused by a cross-section-weakening, rod-shaped foreign particle. As suspected, this was a glass fiber that had fallen from the fracture surface. This was also confirmed by further studies in other damage areas. Presumably, the glass fiber had an unsuitable surface finish for styrene butadiene (SB) and therefore poor matrix adhesion (see also → matrix).

301


SEM Subchapter: Fractures

Crack initiation area

Figure 313 ••Fracture center and tear zone in POM

Figure 313, POM pull rod (M = 40, SEM). The sample was sputtered and examined in the electron microscope with a secondary electron detector. The figure shows a fracture center with a tear propagation zone. The area is pictured in the center of the top fracture edge (see also Fig. 314).

Figure 314

Figures & Text

••Transition area of the tear propagation zone in POM

Figure 314, POM pull rod (M = 400, SEM). Greater enlarged detail from Fig. 313 with a transition area of the fracture center to the tear propagation zone in the center of the figure (Fig. 315).

302



Figure 315 ••Fracture lines in PP are not creep rupture fracture

Figure 315, PP molded part with fracture lines (damaged part, M = 15,000, SEM). The fracture direction with major fracture lines in the image runs from the bottom left to the top right, and the fine fracture lines run perpendicular to that. The fracture occurred rapidly in a bending test. Therefore, in this case, the fracture lines cannot be confused with a creep rupture fracture, in which they would signal a temporarily interrupted fracture progress.

Figure 316

Figures & Text

••Fracture edge with fibrils, ••Fibrils in PB, ••Normal stress zone in PB

Figure 316, PB pipe (M = 2000, SEM). On a fracture edge (fracture surface), the fibrils are perpendicular in the normal stress zone because there, the tensile stress acts vertically in the failure center.

303



Figure 317 ••Fracture edge with fibrils, ••Fibrils in PE

Figure 317, PE molded part with fibrils (damaged part, M = 4600, SEM). The fracture edges have distinct fibrils. These are ductile stretched tips that were caused by the external forces in the failure region when tearing apart the plastic matrix.

Figure 318

Figures & Text

••Layer fracture in PC ••Predrying of PC, poor

Figure 318, PC thermostat valve (M = 34, SEM) with layer fracture. The fracture developed due to poor predrying due to moisture in the molding compound that remained during injection molding and caused embrittlement in the polycarbonate (PC) (see also → predrying).

304



Figure 319 ••Brittle fracture in PE, ••Mold temperature is extremely low

Figure 319, PE rod (M = 33, SEM) with extreme brittle fracture. The cause of the unusual brittle fracture for polyethylene was an extremely cold mold temperature. Therefore, the spherulite in the semicrystalline plastic was suppressed, and the now predominantly amorphous matrix became brittle.

Figure 320 ••Vibration fracture, ••Time fracture lines

Figures & Text Figure 320, PVC molded part with vibration fracture and time fracture lines (M = 3200 SEM). A vibration fracture with many cracks developed through a pulsating load application and appears jerkily from the bottom right to the top left in the picture. The perpendicular running wavelike lines developed due to density or stress differences in the plastic.

305



Figure 321 ••Fracture center in SB, ••Flow parabolas, V-shaped, ••Normal stress zone

Fracture center Flow parabolas

Figure 321, SB fracture center (M = 500, SEM) with normal stress zone and V-shaped flow parabolas (arrows). The lines of symmetry of the two flow parabols intersect, as seen in the picture, in the fracture center. For example, if a fracture center is not visible because it is located on the outside, the fracture origin can still be found. The sample must have at least two flow parabolas, and the fracture center is located at the intersection of their lines of symmetry (see also Fig. 322).

Figure 322

Figures & Text

••Fracture center in SB, ••Fibrils, ••Foreign body, ••Normal stress zone, ••Continuous crack with diagonal fibrils

Figure 322, SB fracture center with normal stress zone (M = 4700, SEM), detail from Fig. 321. The cause of the crack is a brittle foreign body that cracked through the mechanical load itself. In the smooth fracture center, the fibrils are running perpendicular because the tensile force acts vertically and diagonally in the rough radial-shaped continuous crack (see also Fig. 321).

306


SEM Subchapter: Fractures/Delamination

Figure 323 ••Fracture parabolas open in crack direction, ••Crack propagation of fracture parabolas

Figure 323, HDPE drinking water pipe (M = 340, SEM) with fracture parabolas. All fracture parabolas open in the direction of the crack propagation. In the picture, the fracture began in the bottom left and the crack front ran to the upper right. Fracture parabolas begin on a disturbance in a crack initiation area (such as a foreign particle). Here, the disturbance was different-sized pigment conglomerates.

Figure 324

Figures & Text

••Enlarge gate or change injection direction, ••Delamination in a surface, ••Reduce injection pressure, ••Cold plug, ••Turbulent injection

Figure 324, ASA housing with cold plug (M = 50, SEM). During injection, the molding compound froze on the cold mold wall, and with continuously turbulent injection, a frozen molding compound particle (cold plug) was torn out from there, swirled, and washed to the mold wall, opposite the gate. Its edges, which are “not welded” with the plastic matrix, are located in the molded part surface. Cause of damage was a turbulent, oblique injection. We first recommended a lower injection pressure, and if that is not enough, perhaps an enlargement of the gate or a modification of the injection direction (see also → delamination, → filling study, and → turbulence).

307


SEM Subchapter: Electron beam/Thread

Figure 325 ••Electron beam attack in PEEK, ••Surface load through electrons, ••Surface destruction, ••Sample surface in SEM destroyed

Burn mark

Figure 325, PEEK holder (M = 900, SEM). The sputtered sample surface was, after only two minutes of load, destroyed by a 20 kV electron beam (secondary electrons SE). The square, destroyed grid area corresponds to that of a sample surface, which is scanned with an electron beam, after a premade 3500 times magnification. With increasing magnification, the size of the scanned surface decreases in the scanning electron microscope but the energetic surface load increases. Therefore, the observation time and electron beam energy (kV) should be reduced, especially for sensitive samples. PEEK is a polyether ether ketone.

Figure 326

Figures & Text

••Surgical thread in dissolution, ••Implant thread

Figure 326, Surgical thread, a self-dissolving Vicryl filament (M = 5200, SEM) for stitching in the bladder. The surgical thread was sent to us from a clinic for examination under the scanning electron microscope. The surgical thread was strongly attacked after four-day urine exposure, as seen in this image, and it dissolved altogether after a few days. This is very important because no stitches can be taken out after closing the abdominal wall.

308


SEM Subchapter: Warps/Fillers

Figure 327 ••Azo crosslinking, ••Shrinkage in the pipe diameter, ••Cracks and internal warps in PE-X pipe

Figure 327, PE-X pipe, azo crosslinked (M = 16, SEM), freshly produced in delivery condition. The alleged good part had cracks and internal warps. The cause was deliberate diameter shrinkage due to high heating that occurred in this pipe immediately after the production. Thus after extrusion from a larger pipe diameter, different smaller pipe diameters can be produced.

Figure 328

Figures & Text

••Graphite and carbon particles in PTFE, ••Fillers

Figure 328, PTFE slide ring with carbon particles and graphite particles (M = 640, SEM). The fracture point shows carbon and graphite particles under the scanning electron microscope. The approximately 52 micron graphite particles are clearly visible in the laminar structure (sheet structure), and the matte carbon particles are in the range of 55 micron. The particles should improve the abrasion and friction.

309


SEM Subchapter: Fillers

Figure 329 ••Coal particles in POM fillers

Figure 329, POM housing with carbon particles (M = 640, SEM). The dark and matte particles in the image are coal particles. They should improve the sliding properties.

Figure 330

Figures & Text

••Fillers and reinforcing materials in PA, ••Kaolin, mineral filler in PA

Figure 330, PA clamp (M = 4800, REM) with filler and reinforcing materials. Kaolin, a mineral filler to increase the heat resistance and reduce shrinkage, was added to the PA clamp. The glass fiber in the picture could be a reinforcing material to increase the tensile strength. But the single glass fiber was probably an unwanted impurity from a previous batch in the injection unit (see also → masterbatch changes, → granulate contamination, and → material residue transfer).

310


SEM Subchapter: Glass fibers

Figure 331 ••Glass fiber reinforcement in PC, ••Matrix bonding, lower, ••Surface finish of glass fibers

Figure 331, PC-GF25 pressure tank (damaged part, M = 1400, SEM). The matrix of polycarbonate separated from the glass fibers during repeated compressive loads. Some of the glass fiber surfaces are very smooth, and on others, only a few matrix residues adhere. This shows a low matrix adhesion of glass fibers. Causes are usually a faulty or wrong surface finish (such as silane or polyurethane coating) of glass fibers used. The coating of the glass fibers should cause a high force transmission and good adhesive bonding (affinity) with the matrix.

Figure 332 ••Matrix bonding in UP-GF, better

Figures & Text Figure 332, UP-GF housing (M = 960, SEM). Examination of the matrix adhesion of the glass fibers took place after a room temperature fracture at a defined location. A sample was sawed out from the housing and broken with pliers in a vise. As seen under the scanning electron microscope, the matrix adhesion is slightly better than in Fig. 331.

311



Figure 333 ••Matrix bonding in PA, much better, ••Matrix residue on the glass fibers

Figure 333, PA-GF30 molded parts (M = 5000, SEM), good part. Many plastic residues adhere to the glass fiber. This means that the matrix bonding of the glass fibers is very good (see also Fig. 334).

Figure 334

Figures & Text

••Matrix residue, not much, on the glass fibers, ••Matrix bonding, poor

Figure 334, PC-GF30 molded part (M = 5000, SEM), damaged part. Almost no matrix residues adhere to the surface of the glass fiber. That means that the matrix adhesion is poor and thus the possible force transfer between the plastic and the glass fibers is also poor. This results in a limited molded part strength (see also Fig. 332).

312



Figure 335 ••Glass fiber core with bark-like dissolution through sulfuric acid, ••Crystals of sulfuric acid

Figure 335, UP resin sulfuric acid tank (M = 3500, SEM). The surface of the glass fiber separated bark-like due to the attack of sulfuric acid H2SO4 from the core of the glass fiber. Acid crystals grew from the cracks. It looks like they destroyed the surface, the way ice breaks a rock. The bark-like separation is a cold marginal layer of the glass fiber that is due to rapid cooling. This marginal layer formed during the glass fiber manufacture, and their high residual stresses were released by the sulfuric acid.

Figure 336

Figures & Text

••Surface finish of glass fibers, ••Glass fiber fracture, ••Matrix bonding only point-like

Figure 336, PPO GF35 piston (M = 960, SEM) with brittle fracture surface and poor matrix adhesion. The glass fibers have many cracks, and the glass fiber surface treatment, the finish, was obviously unsuitable because the matrix adhesion was only present in a point-like form.

313



Figure 337 ••Filler chalk, ••Matrix bonding, partially good

Figure 337, PVC-GF15 rail (M = 960, SEM) with different matrix adhesion and mineral filler chalk to improve the volumetric shrinkage. The protruding glass fibers are near the exit from the matrix, a partially good adhesion, but not at the end of the glass fibers. Chalk is a filler and processing aid. The chalk content in plastics (e.g., PVC-U) is calculated stoichiometrically from the sufate ash content from about 1.36 × chalk share% (see → sulfate ash content). GF15 means that the polyvinyl chloride rail PVC has a glass fiber content of 15% (see also → birefringence, and → fillers and reinforcing agents).

Figure 338

Figures & Text

••Flow path end with glass fibers, ••Glass fibers are exposed and protrude from the surface, ••Mold temperature, too cold

Figure 338, PA-GF20 bearing shell (M = 280, SEM). Many fibers are parallel in the surface of the new bearing shell and also partly protrude. Cause: Due to a too-cold mold temperature, the more viscous molding compound could not completely cover the glass fibers at the end of the flow path. In use, bearings with this appearance failed.

314


SEM Subchapter: Glass fibers/Glass balls

Figure 339 ••Filler kaolin in FEP, ••Glass fiber diameter, ••Glass fiber length, ••Polyester fibers in FEP

Figure 339, FEP-GF15 molded part (M = 860, SEM), research sample with glass fibers, PETP fibers, and mineral filler kaolin. The glass fibers have a length of about 3 mm and are 10 micron in diameter. FEP is an injection-moldable fluorine-ethylene-propylene copolymer, and PETP is a polyethylene terephthalate.

Figure 340

Figures & Text

••Hollow glass balls increase the dimensional stability, and glass fibers increase the tensile and compressive strength

Figure 340, PA rod with hollow glass spheres (M = 1100, SEM) in the area of a large vacuole. Glass balls increase the dimensional stability in a molded part, for example, in temperature and external pressure load. But they are not suitable, for example, for internal pressure loads in a pressure vessel. Glass fibers are better suited for this because they increase the tensile strength.

315


SEM Subchapter: Glass balls/Implant

Figure 341 ••Glass balls, ••Glass fibers GF, ••Carbon fibers CF, ••Reinforcement materials

Figure 341, PPS precision measurement instrument for temperature measurement (M = 640, SEM) with reinforcing materials: glass balls, glass fiber GF, and carbon fiber CF. The glass balls have a diameter of 42 micron. In the destruction, the GF and CF fibers were partially torn from the fracture surface and broke. Therefore their length could not be determined, which was not required anyways. The fiber lengths could be digitally photographed after a solvent trial and measured on a computer screen (PPS is a heat-resistant polysulfone).

Figure 342

Figures & Text

••Implant pin (self-dissolving) for bone fractures, ••Separation through fracture by hand

Figure 342, PLA98 implant pin (M = 24, SEM). In a research experiment, bone fractures were not “nailed” with stainless steel screws as usual, but secured with a self-dissolving implant pin. The pin, which is hammered into the predrilled bone part, gradually dissolved during the healing process and saved on a follow-up operation. In a series of experiments (Figs. 342–349), the protruding part of the implant pin was removed with different methods, and the separation point was examined for abnormalities under the scanning electron microscope. The picture shows a broken hand fracture surface with a stage fracture. Figs. 342 to 349 show the different appearances of mechanically and thermally separated sectional areas as a comparison.

316


SEM Subchapter: Implant

Figure 343 ••Implant pin (self-dissolving) for bone fractures, ••Separation with surgical tongs

Figure 343, PLA98 implant pin, research experiment (M = 24, SEM). The part of the implant pin protruding out of the fixing was cut with surgical tongs (with two straight edges) and examined under the scanning electron microscope. The cutting surface is clean and has a double-sided cut (front and rear), without outbreaks and splinters. During the surgery, this method is the best because of its easy handling. But even better would be surgical tongs with two cup points (see also Figs. 342 to 349).

Figure 344

Figures & Text

••Implant pin (self-dissolving) for bone fractures, ••Separation with oscillating saw

Figure 344, PLA98 implant pin, research experiment (M = 28, SEM). The part of the implant pin protruding from the fixing was cut with an oscillating saw (plaster saw) and examined under the scanning electron microscope. The cutting surface is strongly deformed and has a raised edge formation and a considerable supernatant (see also Fig. 342 to 349).

317



Figure 345 ••Implant pin (self-dissolving) for bone fractures, ••Separation with oscillating saw

Figure 345, PLA98 implant pin, research experiment (M = 360, SEM). The detail from Fig. 344 shows the protruding part of the implant pin at a higher magnification under the scanning electron microscope. The cutting surface generated plastic deformations when separating the implant pin due to the frictional heat of the oscillating saw (see also Figs. 342 to 349).

Figure 346

Figures & Text

••Implant pin (self-dissolving) for bone fractures, ••Separation with thermal loop at 295 °C

Figure 346, PLA98 implant pin, research experiment (M = 24, SEM). The part of the implant pin protruding out of the fixing was cut with a thermal loop at 295 °C and examined under the scanning electron microscope. The pin has strongly protruding raised edges in the parting surface and wavy, plastic deformations, which developed during the melting (see also Figs. 342 to 349).

318



Figure 347 ••Implant pin (self-dissolving) for bone fractures, ••Separation with thermal loop at 400 °C

Figure 347, PLA98 implant pin, research experiment (M = 360, SEM). The part of an implant pin protruding out of the fixing, detail as shown in Fig. 346 but with higher temperature and magnification, has been cut with a thermal loop at 400 °C instead of 295 °C and examined under a scanning electron microscope with higher magnification, M = 360 instead of M = 24. The separation surface generated wavy, plastic deformations and many melt threads in the exit region of the thermal loop (see also Figs. 342 to 349).

Figure 348

Figures & Text

••Implant pin (self-dissolving) for bone fractures, ••Separation with jet-cutting process

Figure 348, PLA98 implant pin (M = 24, SEM), experimental research. The part of the implant pin protruding out of the fixing was separated with the “jet-cutting process” (0.2 mm nozzle, 1500 bar, v = 100 mm/ min) and examined under the scanning electron microscope. This created a strong frayed parting area with a fibrous supernatant on the outlet side of the high-pressure water jet (right below the numbers in the figure; see also Figs. 342 to 349).

319


REM Subchapter: Implant/Cold flow

Figure 349 ••Implant pin (self-dissolving) for bone fractures, ••Separation with helium laser

Figure 349, PLA98 implant pin, research experiment (M = 28, SEM). The part of the implant pin protruding out of the fixing was separated with a helium laser (He-laser) at a constant output of 20 watts and examined under the scanning electron microscope. This created a smooth, slightly convex cutting surface with low raised edge formation. This process provided the smoothest parting surface. However, due to an increased risk of damage to the patients, the separation of the supernatant using a surgical forceps (Fig. 343) is preferred (see also Figs. 342 to 348).

Figure 350

Figures & Text

••Graining, unwanted, ••Orange skin

Figure 350, PC surface with graining (M = 1000, SEM). The unwanted graining, technically known as “orange skin,” was created during injection molding due to a mold temperature that is too cold (see also → orange skin and → mold temperature).

320


REM Subchapter: Conglomerate/Crystals

Figure 351 ••Fracture area with pigment conglomerates, ••Identification by color pigments, ••Matrix adhesion reduced due to pigments, ••Pigment conglomerates

Figure 351, PVDF fitting with pigment conglomerates (M = 3400, SEM). The spherical pigment conglomerates were partially torn in the fracture area because they did not have a high affinity to the matrix (poor matrix bonding). This is a proof for the dividing effect of pigments. For visual enhancement, identification, and aging resistance, plastics are colored with pigments. This is not dangerous at a low pigment content, but it may reduce the molded part strength at a higher pigment content (see also → matrix and → pigment conglomerate; PVDF is a polyvinylidene fluoride).

Figure 352

Figures & Text

••Salt crystals on the PP surface

Figure 352, PP surface (M = 2400, SEM) of a seawater desalination plant with cracks and deposition of salt crystals (see also Fig. 353).

321


SEM Subchapter: Crystals

Figure 353 ••UV and salt attack of a PP surface

Figure 353, PP surface (M = 640, SEM), scanning electron examination. The surface of a seawater desalination plant was destroyed through a combined attack of ultraviolet sun rays (UV rays) and sea salt (see also Fig. 352).

Figure 354

Figures & Text

••Ca crystals grown in water after 72 h at 90 °C

Figure 354, Ca crystals (M = 1600, SEM). After 72 h, rod-shaped calcium crystals grew in a Würzburg, Germany drinking water sample at a temperature of 90 °C. An approximately 1 cm by 1 cm sample was taken from the crystals and examined and photographed after gold plating (sputtering) using a scanning electron microscope (SEM).

322


REM Subchapter: Painting

Figure 355 ••Bubble in 1C paint, ••Paint defects in 1C paint, ••Paint layer with bubble, ••Air inclusion in the paint?

Figure 355, Tin box (M = 26, SEM). The inside of a box for a refreshment drink was painted for hygiene reasons and to reduce corrosion. With an aging test involving a cooking test in 90 °C hot water, a broken paint bubble developed in the 1C paint layer, probably due to trapped air. The bubble dome collapsed during evacuation in a sample chamber due to the high vacuum of 10–6 torr. A 1C paint layer is a single-component paint layer.

Figure 356

Figures & Text

••Bubble in 2C paint, ••Paint error, ••Paint layer with bubble,

Figure 356, ABS cover with PUR paint bubble (M = 3500, SEM). The paint bubble in the 2C paint layer is broken open due to natural weathering, and the bubble remains at the base of the bubble. The bubble diameter is 10.62 micron. A 2C paint layer is a two-component paint layer. The cause of damage was the UV exposure in outdoor weathering in conjunction with insufficient UV additive in the plastic.

323


SEM Subchapter: Blowholes/Media attack

Figure 357 ••Injection of PBTP, too fast, ••Degassing, insufficient, ••Air inclusion, ••Blowhole

Figure 357, PBTP molded part (M = 1000, REM) with an air inclusion in the surface of a fracture flank. The air inclusion is a blowhole due to entrained air in a too-fast injection of the molding material into the mold. The causes of blowholes are usually residual moisture in the molding compound, thermal decomposition, entrained air in a too-fast injection, or an insufficient degassing in the injection unit (see also → vacuoles and → residual moisture).

Figure 358

Figures & Text

••Etching of SB with chromo-sulfuric acid, ••Butadiene etched, ••Polished sample, ••Styrene globules in SB, ••Ultrasonic cleaning

Figure 358, SB container (M = 4000, SEM). A 2.5 cm × 2.5 cm large sample taken from the SB container was ground, polished, etched with chromic acid, cleaned in an ultrasonic bath, dried, glued with colloidal silver on a Cambridge circle, and then gold plated. In the ultrasonic cleaning, the butadiene content (rubber) was washed out of the cavities, and only the styrene globules, which are visible in the figure, remain. These styrene globules and the removed butadiene made a shock-resistant styrene butadiene SB from an ordinary polystyrene PS.

324


SEM Subchapter: Media attack

Figure 359 ••Island cracks in PP surface, ••Check the media attack beforehand, if possible

Figure 359, PP chair surface (M = 6400, SEM). The chaise lounge was exposed to the sun in Spain for about three years. Many island cracks were generated by the UV radiation of sunlight. With such damage, the additional influence of media exposure from body lotion or sun oils must always be considered. That means that compatibility tests should be performed beforehand, if possible, and chaise lounges that are manufactured with low stress should be used.

Figure 360

Figures & Text

••Media attack for PMMA after the change of cleaning agents, ••Cracks, concentric

Figure 360, PMMA probe tip in a measuring instrument with media attack (M = 320, SEM). The probe tip has many concentric cracks and microcracks due to the influence of a new, cheaper cleaning agent. When using the previous cleaning agent, no damage was caused. Therefore, it is recommended to always check the compatibility before a change and make the appropriate people (for example, buyers) aware of the danger. In the present case, the supposed cost saving resulted in a costly recall with a great loss of reputation (see also → impact assessment).

325


SEM Subchapter: Microbes

Figure 361 ••Microbe growth on PVC film

Figure 361, Microbial growth (M = 1400, SEM) on the surface of a calendered PVC film. The microbe type could not be detected. Presumably there were bacteria or fungi whose growth was favored by the plasticizers in the PVC film. Crystalline residue, however, can sometimes have a similar appearance (see also Fig. 362).

Figure 362

Figures & Text

••Microbe growth on PE film

Figure 362, Microbial growth (M = 1400, SEM) in a drop-like region on the surface of an extrusion-blown packaging film of polyethylene (PE) (see also Fig. 361).

326


SEM Subchapter: Particle

Figure 363 ••Magnesium oxide particle

Figure 363, Fluoroelastomer (M = 2400, SEM) with integrated magnesium oxide particles. They are a maximum of 11.5 micron long and have a diameter of 2 micron.

Figure 364 ••Foreign granulate in PP, ••Particle inclusions

Background

Figures & Text

Background Figure 364, PP molded part with a thickened wall (M = 96, SEM). This was unexplainable by the client. For testing, a gold-plated polished sample through the thickened wall was prepared. Using a scanning electron microscope, particle inclusions (→ foreign granulate) were detected.

327


SEM Subchapter: Fungi

Figure 365 ••Decomposition of silicone due to fungi (Candida glabrata, Candida torulopsis, and Candida albicans)?

Figure 365, Silicone vocal valve (M = 140, SEM). Candida fungi grew into the silicone vocal valve surface. Such a silicone vocal valve is used for laryngeal cancer in the esophagus so that no liquid or food can get into the lungs when swallowing. Depending on the eating habits, deposits develop on the valve-closing surfaces. Because of unfavorable oral and pharyngeal flora the vocal valves of patients often leak after one year. In this case, fungi grew (Candida glabrata, Candida torulopsis, Candida albicans) into the silicone surface and formed together with the food residues knob-like populations in the soft silicone surface (see also Figs. 296, 366, and 367).

Figure 366

Figures & Text

••Decomposition of silicone due to fungi (Candida glabrata, Candida torulopsis, and Candida albicans)?, ••Scalpel cut

Figure 366, Silicone vocal valve (M = 280, SEM). The picture shows a scalpel cut through the fungi growth in the surface of the silicone vocal valve from Fig. 365. After mechanical detachment with a dissecting needle, a permanent crater remained in the soft silicone surface. This was confirmed by numerous studies. Therefore, the very amazing assumption that such fungi, in combination with media load from food, grows into the silicone matrix and can destroy it seems likely. Dissolution of the fungal food conglomerates with different chemicals was not possible (not even with HCl or H2SO4). Incidentally, these fungi are often found in nature and in the mouth and throat (see also Figs. 365 and 367).

328


SEM Subchapter: Fungi

Figure 367 ••Fungus, juvenile form (Candida glabrata)

Figure 367, Silicone vocal valve (M = 6400, SEM), detail from Fig. 365, but from a different area, with unchanged Candida fungi in juvenile form on the soft silicone surface.

Figure 368 ••Fungus (Rhizopus oligosporus)

Figures & Text Figure 368, Rhizopus oligosporus (SEM, M = 2400). In the middle of the figure, the spores of this edible fungus are visible. Around the center sphere, the juveniles form. In Indonesia, the fungus is called tempeh and is grown through rice cuttings, for example, which are cooked in a pan with oil.

329


SEM Subchapter: Cracks

Figure 369 ••Medium depth penetration corresponds to the thickness of the layer delamination, ••Media cracks, ••Carbon black content 50% in SBR, ••Layer delamination due to medium

Figure 369, SBR belt drive (M = 1500, SEM) with 50% carbon black and many media cracks in the totally brittle surface. Because of the depth of penetration of the attacking medium, the brittle surface is peeling off in layers. The layer thicknesses are similar to the depth of penetration of the medium, which was probably the contact spray used in the manufacture.

Figure 370

Figures & Text

••Crazes in PE, ••Fibrils, ••Micro-initiating crack area (craze)

Craze

Figure 370, PE molded part with crazes (M = 14,000, SEM). A craze is a microcrack initiation area with fine fibrils between the crack faces. Crazes (microcracks with fibrils) are only formed in ductile plastics by slow mono- or multiaxial tensile or volumetric shrinkage. Depending on the shape design, especially in mass accumulation with a lack of holding pressure, frozen molded-part stresses cause partially differing volume shrinkages and thereby crazes. In mono- or multiaxial tensile stresses the fibrils are, depending on the angle of the crack edges, more or less inclined with respect to the crack edges. Multiaxial tensile stresses occur at volume shrinkage. The microvacuole in Fig. 376 shows such a case, with fibrils perpendicular to the wall due to multiaxial volume shrinkage. Spontaneous fractures and brittle plastics usually do not get crazes. However, rubber-containing (impact-resistant) plastics can also form crazes at high tensile stress (see also Fig. 376, → fracture center, and → stress whitening).

330


SEM Subchapter: Foams

Figure 371 ••PUR foam, closed-cell, ••Razor blade cut, ••Foam bridges for PUR, ••SE detector, ••Gold plating (sputtering)

Figure 371, PUR-ether foam, predominantly closed-cell (M = 64, SEM). A sample was removed from the polyurethane ether foam using a razor blade and directly examined under the scanning electron microscope with an SE detector after → sputtering (gold plating). Bridges emerged everywhere where the bubbles were touching. Due to the cutting force, single bubbles were torn. The bubble membranes and varying bubble sizes are also clearly visible (see Fig. 372).

Figure 372 ••PUR foam, open-cell, ••Razor blade cut

Figures & Text Figure 372, PUR-ether foam, open-cell (M = 90, SEM). For hygienic reasons (drying), open-cell polyurethane foams are used for sleeping mattresses. A sample was cut from the polyurethane-ether foam using a razor blade and examined immediately under the scanning electron microscope after gold plating with a secondary electron detector (SE detector). The membranes of the bubbles were removed up to the bridges by reduced pressure in a vacuum chamber. Other methods for creating mechanically generated, open-cell polyurethane-ether foams are a hyperbaric treatment in a hyperbaric chamber or rolling, whereby the mattress is squeezed through a narrow roller nip. The aim in all cases is a disentanglement of the membranes for better moisture transfer (see also Fig. 371).

331


SEM Subchapter: Foams

Figure 373 ••PUR foam, slightly open-cell, ••Cold fracture in liquid nitrogen

Figure 373, Polyester PUR foam (M = 240, SEM). The polyurethane bubbles are less open-celled than in Fig. 372. For the embrittlement, the sample was immersed in liquid nitrogen for 30 s and then broken by hand at a spot that was previously cut using a scalpel. The hands were protected with leather gloves. Polyether foams are slightly softer than polyester foams. The sensation of a thin sugar crust is created at contact with your fingers on the surface of polyester foam.

Figure 374

Figures & Text

••PTFE foam, open-cell, ••PTFE foam filter with 1 µm pores, ••Virus filter from PTFE foam

Figure 374, PTFE foam filter (M = 32,000, SEM). PTFE foam filter is a surface filter, and it is placed onto the cone of a standard syringe as a prefilter for medical purposes. A 1 cm by 1 cm sample was taken from the surface filter and directly analyzed under the scanning electron microscopy SEM. The PTFE foam filter has a pore size of, at most, only 1 micron and can thus filter out viruses.

332


SEM Subchapter: Vacuoles

Figure 375 ••Microvacuoles in ASA, ••Lack of holding pressure, partial

Figure 375, ASA housing (M = 1500, SEM), as delivered, with a microvacuole (center) in the fracture surface and barely recognizable small microvacuoles in the surroundings. The effects of external force and cross-sectional weakening by microvacuoles caused the fracture of the housing while in use. The microvacuoles formed in the fracture surface by a partial lack of holding pressure and were the main cause of the damage (see also → microvacuole and → lack of holding pressure).

Figure 376

Figures & Text

••Microvacuole in PPO, ••Craze with fibrils, ••Fibrils (shrinkage fibrils), ••Lack of holding pressure

Fibrils

Figure 376, PPO molded part with microvacuole (M = 7600, SEM). The microvacuole has a diameter of only 8.50 micron and many fine radial shrinkage fibrils. These developed with the slow, multiaxial volume shrinkage on the inner surface because the holding pressure didn’t push enough molding compound through for shrinkage compensation during cooling in the mold. Strong volume shrinkage often causes a partial density difference and can form a cavity (vacuole) in the molding compound (see also Fig. 370, → fibrils, and → microvacuoles).

333


SEM Subchapter: Damage

Figure 377 ••Surface, ripped open, ••Striae, ••Stress marks, ••Deformations, plastic

Figure 377, PEEK molded part surface (M = 320, SEM). The worn molded part surface has stress marks, striae, and a torn-open surface with plastic deformations due to the mechanical stresses in use.

Figure 378

Figures & Text

••Needle-stick in PVC, intentional

Figure 378, PVC surface (M = 2700, SEM) with intentional stab damage. To study stabbing damage, a dissecting needle was pressed deeper into the surface with slight but steady pressure, and it displaced the molding material in a “bow wave” (plastic deformation). The picture was taken under a scanning electron microscope after removal and sputtering of the penetration area (see also Fig. 380).

334


SEM Subchapter: Damage

Figure 379 ••Line marking on PE, structured, ••Molding compound, too cold

Figure 379, PE pipe (M = 4800, SEM) with a structured line marking from entrained poorly molten molding compound particles (granulate) during extrusion. At too-cold processing, these could no longer “weld” sufficiently to close up the surface.

Figure 380 ••Line marking on SB, due to an intentional scratch

335

Figures & Text

Figure 380, SB surface (M = 980, SEM) with an intentionally produced scratch. For the examination under a scanning electron microscope, the surface was gold-plated. In our opinion, such a deep line marking can develop, for example, when a blunt object (screwdriver), pushed by hand, quickly rattles over the surface (see also Fig. 378).


SEM Subchapter: Damage/ LM Subchapter: Cracks

Figure 381 ••Line marking on PA6.6, ••Scratch on PA6.6, ••Wear, plastic

Figure 381, PA6.6 slip ring with scratches (M = 1400, SEM) and plastic wear. The slip ring ran up and down in a guide borehole. The surface was heavily loaded in the wide line markings and smeared due to the resulting thermal stress. The damage was caused by a contamination of the guide borehole.

Figure 382

Figures & Text

••Antidiffusion layer on a PE-Xc pipe with cracks, ••UV cracks

Figure 382, PE-Xc heating pipe (M = 6, AL) with cracks around the screw connection. The damage causes were an embrittlement of the antidiffusion layer on the pipe surface due to solar UV light exposure and bending stresses in the subsequent pipe bend (see also → diffusion barrier).

336


LM Subchapter: Cracks

Figure 383 ••Cold molding in PB, ••Needle shut-off nozzle marking with brittle cracks

Figure 383, PB cover gate (M = 25, AL) with cold molding of a shut-off nozzle. The brittle cracks emerged at a mechanical stress on the back of the cover due to a too-cold processing. A shut-off nozzle, which is located at the tip of the injection unit, prevents accidental leakage of the already plasticized molding material during plasticizing. It opens only at a increasing of the injection pressure.

Figure 384 ••Molded part stresses in PMMA, ••Media influence, ••Shell cracks in PMMA

Figures & Text Figure 384, PMMA light dome (M = 30, DL). The shell cracks started at the surface and ran at an incline into the depth. Cause was the chemical load on the vacuum-formed light dome located over a laundry facility. The frozen molded part stresses were released as cracks. A better preheating of the starting plate before forming reduced the influence of chemical exposure.

337



Figure 385 ••Notch sensitivity of PFA, ••Notch effect, ••Embrittlement of PFA

Groove

Figure 385, PFA valve (M = 31, AL). PFA has conspicuous notch sensitivity when chain degradation occurs during homogenization due to excessive shearing (screw speed). Consequently, a crack developed adjacent to the sealing surface by a notch effect in the sharp groove transition (arrows). Such embrittlement is observed more often in PFA molded parts. PFA is an “injection-moldable PTFE,” a semicrystalline perfluoroalkoxyalkane or perfluoroalkoxy copolymer.

Figure 386

Figures & Text

••Insert component in ABS, ••Insert in ABS, ••Insert preheating, missing, ••Pinpoint gate with needle shut-off valve (no ejector marking), ••Shrinkage cracks,

Figure 386, ABS siphon housing (M = 8, AL). Shrinkage cracks developed in the hub with the brass nut (shown at top center and to the right). The raised, swollen marking (arrow) is a pinpoint gate with needle shut-off valve and no ejector marking. During ejecting, ejectors press the molded part out of the mold and leave no elevation but rather an impression in the mold part surface. The shrinkage cracks developed due to lack of preheating of the brass nut.

338



Figure 387 ••Crack in PVC, close to pipe marking, ••Stress influences, ••Tensile stresses

Figure 387, PVC drinking water pipe (M = 25, AL). The crack starts at the outside of the pipe in the area of an embossed pipe marking with whitish discoloration (arrow), and the break was completed by hand. The customer observed, before the removal of the damaged area, a strong sagging of the pipe because the pipe clamp distance was too great. Because the damaged site could not be visited subsequently, we suspected as the cause of damage the stress influences due to the pipe marking in combination with tensile stresses in the pipe from sagging.

Figure 388

Figures & Text

••Crack in the extrusion groove of PVC, ••Pressure load through single-lever hand mixer, ••Crack initiation, typical

Figure 388, C-PVC drinking water pipe (M = 22, AL). After the intermittent loading of pressure in the pipe, a crack initiated in an extrusion groove in the inner surface. Such a spontaneous pressure load develops, for example, in a house during fast closing of single-lever hand mixers. However, the damage occurred immediately after a fire drill, in which a main valve on the street had been first opened and then closed again.

339



Figure 389 ••Axial crack in PVC with adhesive residue, ••Pressure test, too early, ••Tetrahydrofuran THF, ••THF Adhesive turns white at a too-early contact with water

Figure 389, PVC drinking water pipe (M = 15, AL). The axial crack developed after an application of too much adhesive and a premature pressure test with water when the solvent tetrahydrofuran in the adhesive was not completely evaporated. The solvent softened the pipe in a bump-like fashion, and the partially cured adhesive was squeezed out. Typically, a tetrahydrofuran (THF) adhesive with about 30% dissolved PVC content is used for bridging gaps between the pipe and the fitting. This becomes translucent at a proper pipe venting, but at too-early exposure to water it becomes white and opaque.

Figure 390

Figures & Text

••Pressure overload in PB pipe, ••Longitudinal direction has twice as much load as the transverse direction, ••Beak crack, typical

Figure 390, PB heating pipe (M = 8, AL) with “beak crack” in longitudinal direction. This crack progress is typical at a pressure overload because the longitudinal direction has twice the load (according to boilermaker formula) as the transverse direction.

340



Figure 391 ••Initiating crack area in the fracture center, ••Fracture parabola, concentric

Fracture center

Vacuoles Figure 391, PPE bracket (M = 6, AL). A crack, which is leading to a fracture, always starts in a fracture center with a crack initiation area. From there, “concentric” fracture parabolas spread. A fracture center arises when internal or external stresses act in a thermal (e.g., weld line) or mechanical defect (e.g., damage) or inhomogeneity (e.g., pigment conglomerate). PPE is a polyphenylene oxide.

Figure 392

Figures & Text

••Initiating crack zone in PVC, ••Fracture parabolas

Figure 392, PVC T-piece (M = 8, AL). The initiation crack (arrow) began in the fracture surface, in the center of the fracture parabolas. There, a conspicuous weld is located on the outside of the molded part.

341



Figure 393 ••Orange skin on PA6.6, ••Embrittlement, unusual, ••Marginal zone detachment, ••Mold temperature, too-cold

Figure 393, PA6.6 ram (M = 8, AL) with orange skin on the surface and a brittle fracture, which is unusual for PA6.6 because PA6.6 is a tough plastic. In addition to the brittle fracture, the tongue-like edge delamination (layer separation) is also noticeable (on the right on the picture), which also demonstrates the embrittlement. Cause of the embrittlement was a too-cold mold temperature (see also → embrittlement and → mold temperature, too cold).

Figure 394

Figures & Text

••Dome half with cracks in POM, ••Cold-flow lines

Figure 394, POM driver (M = 10, AL) with broken screw-dome half and thread tear. The causes of damage were a too-high bending torque due to the stainless steel screw that was screwed into the dome and cold-flow lines in the support bars (arrows, see also → cold-flow lines).

342



Figure 395 ••Gate PPSU with crack and cold-flow lines, ••Molding compound temperature and mold temperature are too low, ••Tension cracks?

Gaping crack Tension cracks

Figure 395, PPSU T-molded part (M = 20, AL), gate with gaping cracks (purple), stress cracks (red arrows), and → cold-flow lines (green arrows). The causes of damage were high molded part stresses in the gate area resulting from a too-low mold temperature and a too-low molding compound temperature that caused the crack and the stress cracks during ejection. A too-low molding compound temperature is much rarer than a too-low mold temperature (see also Fig. 396).

Figure 396 ••Gate PPSU with shrinkage cracks in a mass accumulation

Figures & Text

Shrinkage cracks

Figure 396, PPSU T-molded part (M = 15, AL). A microscopic examination showed, after a crack extension up to the fracture, that the suspected stress fractures (red arrows in Fig. 395) are in reality concentric circumferential shrinkage cracks in a mass accumulation at the gate.

343



Figure 397 ••Material overstretching in a PP pipe at a pressure test

Figure 397, PP pipe (M = 12, AL) with material overstretching and fine cracks in the pipe after a pressure test with a too-high test pressure for leaks (pipe test).

Figure 398

Figures & Text

••Damage reenactment through aging tests in SAN, ••Shrinkage cracks due to shrinking on, ••Heat exposure, 90 °C

Figure 398, SAN container (M = 6, AL) with shrinkage cracks. After about a year, shrinkage cracks formed on the container bushing through shrinkage onto the stainless steel shaft. Such surface cracks, after 24 h of heat treatment at 90 °C, were observed in an aging test in a convection oven for damage reenactment. Causes of damage were a too-low mold temperature and that caused high molding stresses. A subsequent tempering of the molded parts was not recommended for the high quantities. Therefore, the batch could not be saved. We recommended considering a future preheating of the stainless steel shafts and an increase of the mold temperature to 75 °C (see also → damage reenactment and → tempering).

344



Figure 399 ••Flow line in C-PVC, line-like gaping, ••Molded part stresses

Figure 399, C-PVC fitting 90° (M = 6, AL). The outside of the fitting has a gaping, weld-line-like flow seam with very high molded part stresses over a pipe, which is glued with THF adhesive. The damage area has been marked by the customers with a white felt-tip pen. The flow seam developed through an unexpected confluence of mass flows at an unexpected spot. In contrast, a weld line is formed at an expected place, which is usually after a core flows in the confluence of the mass flows (see also Fig. 400).

Figure 400 ••Flow seam, opened

Figures & Text Figure 400, C-PVC fitting 90° (M = 6, AL). The weld line on the exterior of the fitting in Fig. 399 was forcefully broken open. The unfolded, adjacent fracture surfaces show a vertical crack in the weld-line-like flow seam (on the outside of Fig. 399) and a horizontal crack in the top half. The red-brown color is rust. High molded part stresses due to a too-cold processing caused the damage when they were released by the solvent content in the adhesive.

345



Figure 401 ••Pressure point in PVC-U pipe (stone print), ••Y-crack in PVC-U

Figure 401, PVC-U pipe (M = 6, AL) installed in a bed of sand in the soil. On the outer surface of the pipe, an axial Y-crack (the white lines from left) runs perpendicular to a mechanical pressure point (dent, see arrows) with indented sand grains. The pressure point was probably caused by a stone that fell into the sand bed when inserting the pipe (see Fig. 402).

Figure 402

Figures & Text

••Notch effect, ••Deformation, permanent (dent)

Figure 402, PVC-U pipe (M = 6, AL). The mechanical pressure point in Fig. 401 is exactly perpendicular to the Y-crack. The damage cause was probably a stone that barely pushed on the permanently installed PVC pipe in the soil and generated high stresses. Evidence for this is the permanent deformation. The impressed sand grains could also be damaging (notch effect).

346



Figure 403 ••Axial cracks in C-PVC pipe after heat treatment, ••Pressure stresses, ••Heat exposure at 150 °C generated cracks, ••Tensile stress

Axial cracks

Figure 403, C-PVC drinking water pipe DN 20 (M = 12, AL), inside of the pipe with axial cracks. After only 0.5 h of heat treatment at 150 °C, gaping cracks emerged, without connection to the outside of the pipe, on the inside of a previously crack-free pipe section. Causes: The pipe outside is compressed during calibration and quickly frozen in a water bath with compressive stresses while the not-cooled, still-warm inside of the pipe further shrinks (tensile stresses). The reason why internal axial cracks often develop in heat-conducting pipes (without external cracks) is, for example, explained in the following tempering process. In heat treatment in a convection oven, the stress gradient decreases 150 °C between the pipe outside and the pipe inside, and with the decreasing pressure stresses, the outer pipe diameter increases again (springs back), as does the now-tempered “inside pipe diameter.” Therefore, axial cracks arise in the inside of the pipe in the area of pigment streaks or pigment conglomerates (see also → extrusion and → tempering).

Figure 404

Figures & Text

••Conchoidal fractures, multiple, in PE63 drinking water pipe, ••Carbon black conglomerate in fracture centers, ••Resistance to internal pressure test according to DIN 8075 for HDPE pipes, ••Creep internal pressure tests according to DIN 8075 for HDPE pipes

Figure 404, PE63 drinking water pipe (damage, M = 25, AL-DF) without DVGW registration number and DIN marking. The pressure points on the outer surface of the pipe indicate bending stresses such as, for example, through stones in the sand bed, which resulted in a slow crack growth together with the internal pipe pressure. This type of failure is known for PE pipe materials of the first generation (PE63). It was also successful, in a creep internal pressure test according to DIN 8075 for HDPE pipes, Appendix A, to recreate a fracture with multiple conchoidal fractures. Furthermore, 10 micron thin sections showed large pigment conglomerates up to 70 micron, which also favored the fracture. Damage causes were therefore bending stresses due to a faulty transfer into the sand bed and inhomogeneities due to a lack of homogenization. The samples, which were taken from the damage area for IR and DSC analyses, were normal, and foreign material was not found. (DVGW is the German Association for Gas and Water).

347



Figure 405 ••Pigment conglomerate, up to 70 µm cracks release themselves


Figure 405, PE63 drinking water pipe 50 × 4.6 (M = 25, DL). Several 10 micron thin sections through various locations in the fracture area of the multiple conchoidal fractures (Fig. 404) show very large pigment conglomerates up to a size of 70 micron. The conglomerates were the crack-causing disturbances in crack initiation areas of the conchoidal fracture.

Figure 406

Figures & Text

••Cracks in PE end cap, ••Comparable examination, Figs. 406 to 410

Figure 406, PE end cap (damaged part, M = 1 : 1) in delivery state. The bottle neck presses down when the red end cap is screwed on for sealing. After filling, the bottles were packed in cardboard boxes with compartments and shipped in the summer. After unpacking, many caps were broken and the contents partially leaked. As a cause of damage, a high tightening torque when screwing down was suspected along with a high vapor pressure due to a solar influence when shipping (arrows). However, as Figs. 407 to 410 prove, a high vapor pressure was not to blame, but instead a unsuitable buttress thread.

348



Figure 407 ••PE end cap with buttress thread, ••Comparable examination, see Figs. 406 to 410

Buttress thread

Figure 407, PE end cap (damaged part, M = 6, AL). A polished sample through the crack area in the damaged part shows an unsuitable buttress thread for plastics with one-sided sharp-edged thread edges of 90°. This sharp transition favored a notch effect, which is initiated a fracture (see Figs. 406 to 410).

Figure 408 ••PE end cap with round thread, ••Comparable examination, see Figs 406 to 410

Figures & Text

Round thread

Figure 407, PE end cap (good part, M = 6, AL). In a good part, prepared in the same manner as the defective part in Fig. 407, which is a polished sample. The thread here is a suitable plastic round thread (see Figs. 406 to 410).

349



Figure 409 ••Crack in PE end cap due to notch effect (damaged part), ••Comparable examination, see Figs. 406 to 410

Crack

Thread

Figure 409, PE end cap (damaged part, M = 6, AL). The halved cap from the end cap of the part damaged during shipping was screwed to the threaded neck of the bottle. It became clear that due to the contact force between bottle neck and screw cap, the last thread of the end cap was cracked circumferentially by the screwing movement (arrow). The one-sided, sharp-edged, last thread flank in the buttress thread favored the fracture (see Figs. 406 to 410).

Figure 410

Figures & Text

••Crack in PE end cap, ••Screw connection without crack (good part), ••Comparable examination, see Figs. 406 to 409

Figure 410, PE end cap (good part, M = 6, AL). For comparison, the end cap of the good part has been halved at the same spot and screwed onto the threaded neck of the bottle. The threads were less deformed through their larger cross-section of the screw. Obviously, the screwing moments on the many good parts that were also delivered did not lead to small cracks (arrow) in the end cap (see Figs. 406 to 409).

350



Figure 411 ••Misinterpretation of cracks, ••Cracks in PS, fine, can be misinterpreted, ••Toluene content in Canada balsam

Figure 411, PS cover (M = 25, DL), 10 micron thin section with fine cracks on the inside of the molded part. Caution! Such fine cracks, which run perpendicular to the cutting direction, may also have the following causes: they were already present on the inside of the molded part or the withdrawal speed was too great in the thin section manufacture (preparation errors) or internal molded part stresses were released due to the toluene content in Canada balsam (adhesive). This is however very rare.

Figure 412

Figures & Text

••Beak crack in PB pipe, ••Thermal damage of a pipe through continuous contact with radiant heat

Figure 412, PB heating pipe (M = 1 : 1). In the damaged area, the heating pipe crossed with an uninsulated, 90 °C warm copper pipe with continuous contact. Through the constant radiation heat, the heating pipe in the intersecting area was thermally damaged with time, and finally a typical “beak crack” developed there due to the internal pressure in the heating pipe.

351



Figure 413 ••Brittle fracture for ASA, ••Incident light combined with transmitted light, ••Contrast method

Figure 413, ASA plate (M = 10, AL + DL combined). Die plate shows a typical brittle fracture with initiating crack and fracture centers. A fracture is, by the way, a completed crack.

Figure 414

Figures & Text

••Shear crack in ETFE radome dome

Figure 414, ETFE piping sample (M = 30, AL). Shear cracks developed (arrows) in a tensile test on a specimen cut of the size of 500 mm × 50 mm from a radome dome (“ball-tent roof”) in the joining plane.

352



Figure 415 ••Cracks in POM through hydrolysis, ••Aging, ••Decomposition of the surface

Figure 415, POM switch housing (M = 30, AL) with heavy aging and the typical image of hydrolysis. The surface dissolved into hilly structures and between them developed deep cracks. There are POM varieties, which are particularly sensitive to hydrolysis, where the surfaces are attacked by moisture and water at temperatures from 60 °C.

Figure 416 ••Aging of POM, ••Cracks, insular

Figures & Text Figure 416, POM surface of a crane switch (M = 33, AL) with heavy aging. The surface decomposition began after about five years under the influence of moisture and lubricating oil. Many deep insular cracks developed. During the period of use, a high temperature influence of up to 65 °C was measured by the client. Therefore, we suspect a hydrolytic decomposition in conjunction with a lubricating oil influence.

353



Figure 417 ••Dome crack in PC-CF10 screw dome, ••Thread, torn out

Figure 417, PC-CF10 plastic housing (good part), polished sample (M = 10, AL) through a screw dome, close to the gate with two clean-cut threads. The first thread started about 1 mm deep into the core borehole (arrows) and therefore did not crack like the damaged part in Fig. 418 did, which was caused by the cutting force during thread cutting (see also Fig. 419).

Figure 418

Figures & Text

••Tightening torque in PC-CF10 too high, ••Thread, torn, ••Screw, self-tapping, ••Screw guide, oblique

Figure 418, PC-CF10 plastic housing (damaged part), polished sample (M = 10, AL) through a screw dome, which is close to the gate with a torn-out thread. The self-tapping screw penetrated deeper into the core borehole than in Fig. 417. And the first thread is already located in the cylindrical countersink (arrows), instead of about 1 mm deep in the core borehole. Through tearing of the thread and poor guidance, a wobble motion followed when screwing down. Causes of damage are a premature setting of the first thread and poor screw guidance. An excessive tightening torque and the wobbling motion of the screw tip scraped the core drilling. Remedy: screw down the screw centrically, check the diameter of the borehole and the torque moment, and smooth possible roughnesses. This reduces the screw resistance (see Fig. 419).

354


LM Subchapter: Cracks/Foams

Figure 419 ••Thread in PC-CF10 torn, ••Carbon fibers homogeneously distributed

Figure 419, PC-CF10 plastic housing (good part), 10 micron thin section through the screw dome in Fig. 418. The distribution of the carbon fibers is unobtrusively homogeneous and thus had no negative influence on the damage (see Fig. 417).

Figure 420

Figures & Text

••Bubble structure in polyether foam, inhomogeneous, ••Cold fracture in nitrogen N2, ••Polyether foam PUR, ••Preparation in nitrogen N2, ••Depth of field, insufficient

Figure 420, Polyether polyurethane PUR (M = 25, AL), with a few oversized bubbles. For the preparation, the sample was stored for 10 min in liquid nitrogen N2 and then broken with gloved hands. The thus-produced cold fracture made the inhomogeneous structure of bubbles with bubble sizes from 160 micron to 440 micron visible. The stereomicroscope used had a still-sufficient depth of field for the structural examination and measurement. A scanning electron microscope is recommended for finer structures because of its much greater depth of field.

355


LM Subchapter: Layers

Figure 421 ••Ca deposits, ••Perforation, ••UP resin coating, not leaking

Ca deposits

Perforation

Figure 421, UP resin coating with glass mat (M = 25, AL) on the concrete wall of a pool. In the UP resin coating, a leak with limescale deposits was found. The damage cause of the perforation is probably a nonexpelled bubble (bubble formation) in the UP resin coating during lamination and curing. The Ca deposits are from the water.

Figure 422

Figures & Text

••Permeation layer in PE oil containers

Permeation layer

Figure 422, PE oil container wall (M = 30, AL). With a polished sample through the layered wall structure, a 75 micron thick permeation layer on epoxy resin basis was visible. After the manufacture of the oil container in blow molding, this layer was sprayed on the internal vessel wall of the container to reduce the permeation (passage) of toxic and strong-smelling oil vapor.

356



Figure 423 ••Bubble size, inconspicuous, ••Integral foam thickness of PVC-U, ••Integral layer thickness varies, ••Core-foamed PVC-U pipe, ••Polished sample, ••Pipe, core-foamed, ••Foam thickness varies

Varying foam thickness

Figure 423, PVC-U pipe, DN 200, core-foamed (M = 12, AL). A polished sample shows an inconspicuous foam structure but with a different integral foam thickness. The goal in the production must be to ensure as equal as possible bubble size and same outer skin thicknesses. For the microscopic examination, a block section in the microtome would be produced faster and more accurately than for a polished sample.

Figure 424 ••Delamination of PP, ••Delamination, causes

Figures & Text Figure 424, PP warming tray (M = 6, AL) with a grained surface and delamination on the tray edge. Causes of delamination are tool oils, greases, pigment separation layers due to subsequent coloring or poor homogenization, high injection rate with shear flows in the cold mold, shape, molding compound exchange, foreign material, cold spots at low temperature, or a media attack (cleaning agent) at tension filled shear zones. In this case, the causes of damage were a subsequent masterbatch coloring with poor homogenization and foreign material (see also Figs. 425 and 426).

357



Figure 425 ••Coloring of PP, subsequent, ••Homogenization, poor, ••Matrix adhesion, reduced, ••Pigment streaks, ••Pigments reduce molded part resistance

Figure 425, PP warming tray (M = 30, AL). A 10 micron thin section through the delamination in Fig. 424 shows clearly that the delamination of the pigment streaks follows (arrows). Cause was a subsequent coloration and poor homogenization of the masterbatch. Basically, pigment streaks have a divisive effect in the molding compound because the pigments are not bonding with the matrix. Therefore, they should be used sparingly (see Figs. 424 and 426).

Figures & Text

Figure 426 ••Coloring of PP, subsequent, ••Large spherulites in small spherulitic PP matrix, ••Nucleating agents or foreign material?, ••Spherulite, atypical

Figure 426, PP warming tray (M = 100, DL-POL). A 10 micron thin section through the delamination (Fig. 425) shows an atypical spherulite structure of the molding compound with large spherulites in a small spherulitic matrix, as with an addition of nucleating agents. The spherulites in polypropylene PP have the appearance of asters and pansies in polyamide PA. Therefore, the large spherulites point to polyamide (foreign material) after a previously performed molding compound change. This was also confirmed using IR and DSC analyses. The damage causes of the delamination in Fig. 424 were therefore pigment streaks by subsequent coloring and poor homogenization, as well as unwanted polyamide residues (foreign material), and possibly also a nucleating agent.

358



Figure 427 ••Contrast improvement through combined contrast methods, ••Embossing film, PVC

Acrylic coating

Laminating film Adhesive

PVC-Profile Figure 427, PVC-U window profile section with PVC embossing film (M = 500, DL-POL + -plate + DIC and partially closed aperture diaphragm). An 8 micron thin section through the layer structure shows, in a deliberately incorrectly inserted DIC slider 10x/50x, 0.30 instead of 0.75, a blue coloring in the otherwise water-clear adhesive layer, and bubbles. The PVC embossing film (PVC wood grain decorative film with a PMMA topcoat) was laminated with a polyurethane adhesive to the PVC-U window profile. As the example shows, the courage of a seemingly senseless combination of the contrasting methods is recommended for better visibility of low-contrast samples.

Figures & Text

Figure 428 ••Bubbles formation after 285 °C temperature exposure, ••Air injection, ••Heat exposure of PA GF35 at 285 °C

Layer crack

Figure 428, PA-GF35 glass holder (M = 20, AL), polished sample with a layer crack (arrows). After temperature exposure at 285 °C in a convection oven, there was a large bubble formation because air was trapped when injecting the molding compound into the mold. To avoid a future air injection, it was recommended to the customer to increase the nozzle contact force (see also Fig. 429).

359



Figure 429 ••Delamination of PA GF35 through air injection

Layer

Layer

Figure 429, PA-GF35 glass holder (M = 20, AL), polished sample with a layer crack, sequel to Fig. 428. In another area, the original molded part wall (delamination layers) separated into two layers because of an air injection and formed a large bubble due to a temperature exposure at 285 °C (see also → delamination).

Figure 430

Figures & Text

••Shear stresses in PC, ••Back injection, ••Layer delamination

Layer delamination

Figure 430, PC car radio button (M = 8, AL) with polyamide back injection. First a PC film was molded by vacuum forming, then inserted in an injection mold and back-injected with polyamide PA6 for stabilization. The layer delamination at the button indicates high tensile stresses in the PC film, which is back-injected with polyamide PA6. The damage was caused by a superposition of the tensile stresses with additional shear stresses due to shrinkage of the PC film onto the back-molded polyamide, in the boundary area between PA6 and PC film. The tensile stress and superimposed shear stresses caused the layer separation at the button margin (see also Fig. 431).

360



Figure 431 ••Wall thickness distribution, unequal, of a vacuum formed and back-molded PC film

Figure 431, PC car radio button (M = 10, AL). A polished sample through the button, which is back-molded with polyamide PA6, shows an expected uneven wall thickness distribution in the vacuum formed PC film (dark layer) of 92 micron to 192 micron. To avoid future damage, an optimization of the wall thickness distribution was recommended (see also Fig. 430).

Figure 432 ••Delamination of PFA

Figures & Text

Delamination

Figure 432, PFA disc (M = 12, AL) with delamination of the surface. Causes were long filling times during injection molding. With an increasing filling time, the molding compound layer, which is first freezing on the cold mold wall close to the gate, became thicker and colder. But because more molding compound under this cold layer still flowed to the end, the two layers “welded” insufficiently and therefore parted (delaminated) in use.

361



Figure 433 ••Film hinge with PP layer formation, ••A molding compound, cold, ••Layer flows cold

Figure 433, PP film hinge (M = 25, DL-POL). A 10 micron thin section through the film hinge area shows strong layer flows due to a too-cold flow. The cause was a low mold temperature. The molding compound that is in contact with the mold froze quickly (in the figure the upper and lower parts), and the subsequently flowing compound passed in between, from right to left.

Figure 434

Figures & Text

••Delaminations of PVC, close to the gate, ••Cold-flow areas

Figure 434, PVC-KG bow DN 100/30° (M = 6 AL) with cold-flow areas and strong delaminations close to the gate on the outside of the pipe. The damage was caused by a too-rapid injection into a too-cold mold. Because of the swirling, hot and cold molding compound areas mixed in a mass whirling and could not properly connect again (see also Fig. 435 and → delamination).

362



Figure 435 ••Cold-flow areas in PVC, extreme

Figure 435, PVC-KG bow DN 100/30° (M = 6, AL), detail back of Fig. 434 with extreme cold-flow areas (arrows) on the pipe interior surface. The high molded-part stresses, which froze in mass whirls, caused cracks in use, leading to breaking up the surface.

Figure 436 ••Block ground sample with layer thickness determination of a composite film with seven layers, ••Block ground sample of a composite film

Figures & Text Figure 436, Composite packaging film (M = 200, AL) with four films and three adhesive layers (two polyethylene outer layers and an inner layer made of PETP and PA). To determine the layer thicknesses, the composite film was screwed between two PVC pieces and carefully ground with wet abrasive papers 350, 500, 1200, and 2500, so the film layers did not smear. The 20 micron total thickness of the packaging film was measured with a dial gauge, and the film thicknesses of the outer and intermediate layers of the block ground sample were viewed under the microscope. Their layer thicknesses were, from top to bottom: 4 micron, 4 micron, 2 micron, and 5 micron. True layer thicknesses are generally only measurable with a block section in the microtome or in the clamping block method. A thin section tends to contract transversely and cut overstretching and thus leads to wrong layer thicknesses. Also, the present block ground sample is unfavorable because the film layer edges are torn or over-smeared.

363



Figure 437 ••Layer thickness determination for PMMA/ABS/PC with thin section, ••Block section is more suitable

Figure 437, PMMA/ABS/PC tanning bed (M = 50, DL). A 10 micron thin section through the layer structure showed in the figure from left to right with the following values: 55 micron for the transparent PMMA layer and 210 micron for the protected decorative layer, and the total film thickness was 652 micron. Caution: a thin section is only suitable for a reliable determination of the number of layers. The actual layer thicknesses, however, should be better measured on a block section because the thin section may include, depending on the measurement sharpness, different compressions. In this case, the error deviation between a thin and block section was very low at only 3%.

Figure 438

Figures & Text

••Double laminating, ••Of embossing films, unintentionally or intentionally?

Figure 438, PVC-U window profile with double lamination (M = 25, DL-DIC + ), 10 micron thin section. For an attractive appearance, window profiles are, for example, laminated with a wood-grain decorative film. As seen in the figure, this happened twice. However, a different colored laminating film was used for the second lamination (1 = PMMA layer, 2 = PVC decorative film, 3 and 4 = PUR adhesive, the primer was in both cases not recognizable). The double lamination may therefore not happen accidentally but because of a design change. Presumably the same PUR adhesive was used in the second lamination because it has partly the same color (3 and 4) but a significantly greater coating thickness.

364



Figure 439 ••Air inclusion in the welding zone of PE, ••Welding of the winding position of a winding tube, ••Roller tube

Figure 439, PE winding tube (M = 12, DL-POL + ). A 10 micron thin section through the layered structure of the winding tube shows air inclusions in the weld zone between the light and dark winding layers (light PE and black). That is, the welding pressure was not optimal in the welding.

Figure 440 ••Oxygen diffusion barrier in a PB composite pipe, ••Oxygen corrosion, ••PB composite pipe with diffusion barrier

Figures & Text Figure 440, PB heating pipe (M = 8, AL). The block ground sample shows a composite pipe tube and AL jacket as a diffusion barrier against oxygen diffusion into the heating pipe. The diffusion barrier should prevent, during the heating period, O2 from entering the pipe and causing corrosion in the heating system (see also → oxygen diffusion barrier).

365



Figure 441 ••Etching with 30% nitric acid, ••Zinc layer thickness measurement

Casting

Zinc layer

Figure 441, Cast iron socket 3/4 in., zinc-plated (M = 50, DF-AL). A polished sample through the cross-section of the cast iron socket was first ground with wet-strength silicon carbide paper with grain sizes 320, 500, 800, and 1200 and then polished with the grain sizes 2400 and 4000. After about 10 s etching with 30% nitric acid, the zinc layer was visible on the cast iron sleeve, and the zinc layer thickness could be measured. It amounts to 53 micron. A 70% nitric acid was a little too sharp, but 100% acetic acid also results in a good contrast (see also Fig. 442).

Figures & Text

Figure 442 Zinc layer

Casting Figure 442, Cast iron socket 3/4 in., zinc-plated (M = 50, DF-AL), detail from Fig. 441 in another area. After about 10 s etching in 100% acetic acid, the zinc layer on the cast iron sleeve was also clearly visible, and the zinc layer thickness could be measured. It amounts to a maximum of 102 micron.

366

••Etching with 100% acetic acid, ••Zinc layer thickness measurement



Figure 443 ••Coextrusion of ABS/PC

Figure 443, ABS/PC housing (M = 25, DL). A 10 micron thin section through the housing wall shows the coextruded ABS and PC layers very clearly in normal transmitted light. In the polymer blend ABS/ PC, the ABS top layer improves the gloss and the polycarbonate PC the strength. ABS is an acrylonitrile-butadiene-styrene copolymer.

Figure 444

Figures & Text

••Air intake in PP surface, ••Delamination, cause for electroplating errors

Figure 444, PP film hinge (M = 100, DL-POL). A 10 micron thin section shows delamination with air intake in the cold marginal zone due to the molding compound whirls during injection. Such surface defects often caused complaints at subsequent painting, vapor deposition, or electroplating. There, due to trapped air or liquids that made their way in (for example demolding agents or bath fluids), bubbles developed under the palladium layer application and the resulting first electroplating layer. But the bubbles can initially expand before they are covered by the following metal layers (see also → electroplating error).

367


LM Subchapter: Streaks

Figure 445 ••Pigment distribution in HDPE, ••Poor bridge marking, ••Torpedo bridges in the extruder

Figure 445, HDPE sewage pipe (M = 10, DL), 10 micron thin section with an inhomogeneous distribution of pigments and bridge marking. The torpedo (mandrel) in the extruder is held with bridges. The molding material flows around the bridges and then connects again. These locations are identified as bridge markings with insufficient homogenization with poor pigment distribution.

Figure 446

Figures & Text

••Masterbatch coloring of ABS, ••Pigment streaks in subsequent coloring, ••Pigment streaks are weaknesses

Figure 446, ABS siphon (M = 30, DL). In a 10 micron thin section, pronounced pigment streaks through the masterbatch can be recognized close to the gate due to insufficient homogenization. The pigment streaks are weaknesses that preferentially form cracks at external, mechanical stress.

368



Figure 447 ••Streak, brown burn, in SAN

Figure 447, SAN spacers (M = 8, DL) with a brown burn streak (arrow). One explanation can be found in the text in Fig. 448.

Figure 448

Figures & Text

••Diesel effect in SAN, ••Friction by rapid injection, ••Dead corners in the mold, ••Burn streaks SAN, ••Dwell time, too long, ••Mold venting, insufficient

Figure 448, SAN spacer (M = 28, DL), detail from Fig. 447 with brown burn streak (arrow). Burn streaks were caused by an overheating of the molding compound in “dead corners,” friction in a narrow distribution channel, or a high air compression of up to about 1500 °C due to insufficient mold venting, or high injection rates. This results in a brown to black burned surface area. This process is also called “diesel effect.” In the present case, the molding compound was, however, thermally damaged in “dead corners” of the mold, after a too-long dwell time (homogenization time) in the injection unit, and turned brown to black. The same happens particularly for thermally sensitive plastic materials (for example PVC). Then brown streaks usually occur in the interior of the injection-molded part (see also → shearing).

369



Figure 449 ••Injection rate is too high, ••Burn streaks in PC

Pin point gate

Figure 449, PC filter housing (M = 20, DL), pinpoint gate (∅ 1.30 mm) with internal burn streaks due to too-high injection rate (see Fig. 450 and → burn streaks).

Figure 450

Figures & Text

••Burn streaks, cloud-like

Figure 450, PC filter housing (M = 50, DL) enlarged detail from Fig. 449 with cloud-like, internal burn streaks.

370



Figure 451 ••Foreign material PP in PE, ••Sieve or perforated disc imprint with pigment and spherulite streaks

Figure 451, PE drinking water pipe, African (M = 8, DL). The 10 micron thin section shows a sieve or perforated disc imprint in transmitted light bright field, which was visible as a result of subsequent coloring with a masterbatch and poor homogenization (see also Fig. 452).

Figure 452 ••Coloring, subsequent, ••Foreign material PP in PE, ••Sieve or perforated disc imprint

371

Figures & Text

Figure 452, PE drinking water pipe, African (M = 50, DL-POL + ), enlarged detail from Fig. 451 with a sieve or perforated disc imprint through the extrusion as well as pigment and spherulite streaks. The spherulites, which are microscopically too large for polyethylene PE, as IR and DSC analyses revealed, are polypropylene PP residues from the extruder (foreign material) after a molding compound exchange.



Figure 453 ••L : D ratio is too large, ••Mass flows, many, ••Screw size L : D, ••Structure of PE, inhomogeneous, due to poor homogenization

Figure 453, PE plate (M = 25, DL). The 10 micron thin section has a noticeably inhomogeneous structure and pronounced pigment streaks. They were formed during extrusion by subsequent coloring of the molding compound and a poor homogenization due to a back pressure that was too low. Such errors also occur when the melt temperature, screw speed, or the L : D ratio is too large (L = screw length, D = screw diameter).

Figure 454

Figures & Text

••Coloring, poor, ••Masterbatch for PE-X, ••Residual granulate, unmelted, ••Carbon black streaks, strong, ••Bridge marking

Figure 454, PE-X heating pipe 18 × 2.0 (M = 6, DL). The 10 micron thin section shows an unmelted residual granulate, bridge marking, and poor coloring pigment due to a subsequently incorporated pigment additive (see also → masterbatch and → residual granulate).

372



Figure 455 ••Pigment streaks, weakening, ••Pigment streaks, faintly drawn, with crack

Figure 455, ABS clothesline (M = 100, DL) with cracks. Cracks emerged at a mechanical load. They follow the weak drawn pigment streaks caused by a subsequent coloring and insufficient homogenization. Pigment streaks always act divisively and disruptively to the intermolecular bonding forces in the polymer structure. However, this incident was unusual because such a large crack occurs only in heavily drawn pigment streaks.

Figure 456 ••Color pigments as cause of damage, ••Color streaks, weaken

Figures & Text Figure 456, TPE bed slat support (M = 6, AL) with color streaks in the fracture surface. Cause of damage was an insufficient distribution (homogenization) of the color pigments. The color streaks with high pigment content have a separating effect in the polymer matrix, leading to fracture at a tensile load.

373



Figure 457 ••Ejector marking, ••Diesel effect, ••Injection burrs, ••Mold venting, poor

Figure 457, PC housing, impact resistant, (M = 6, AL), with an ejector marking, brown discoloration (blue arrow), and an injection burr (red arrows). The ejector marking indicates a little-too-early demolding, the brown discoloration on the ejector (see Fig. 459) is explained by a too-rapid injection or poor ventilation, and the injection burr is based on a too-high injection pressure.

Figure 458

Figures & Text

••Flow waves and burn streaks, barely visible

Figure 458, PC housing, impact resistant, (M = 10, AL). Details from the housing in Fig. 457 in a different area, with barely visible, brown burn streaks on the ejector marking and fine flow waves in the surface of the molded part (see also → streaks).

374



Figure 459 ••Diesel effect, ••Injection, too fast, ••Burn streaks, ••Mold venting error

Figure 459, PC housing, impact resistant (M = 25, AL without a blue filter). Detail from Fig. 457 (but in another area) with clearly visible brown burn streaks. Due to a too-fast injection or poor mold venting, the trapped air was highly compressed during injection and heated to temperatures of up to about 1500 °C (diesel effect). Therefore, the molding compound burned partially. The image was made without a blue filter and has therefore a yellow tint. A blue filter or a sickle aperture prevents a yellow tint with a halogen light image. The sickle aperture controls the brightness without changing the color temperature.

Figure 460

Figures & Text

••Color streaks through shear flows, ••Hot-cold streaks, ••Color streaks through flow layers, ••Color streak effect due to knife nicks

Figure 460, PA11 molded part (M = 100, DL-POL + ) with color streaks in a 10 micron thin section. The streaks only became visible under polarized light in conjunction with a lambda plate. The causes of the color streaks are nicks in the microtome and an unfavorable injection with flow layers and shearing in the transitions (shear flows). But such color streaks can also develop with a too-short homogenization, a thermally inhomogeneous molding compound (hot-cold streaks), or a physically inhomogeneous molding compound is injected in a subsequent coloring (color streaks).

375


LM Subchapter: Welding

Figure 461 ••Foreign particles in weld line, ••Heating element weld line, poor, with air pockets

Figure 461, PB mushroom valve (M = 6, DL). A 10 micron thin section through the heating element weld line shows uncolored areas (arrows) and carbon black particles in the molding compounds. Furthermore, the pronounced weld beads and uneven wall thickness of the joining partners are striking. Obviously, the molding compound was subsequently colored with a carbon black masterbatch but poorly homogenized. And the large weld beads developed through a too long heat-up time (as confirmed by the client).

Figures & Text

Figure 462

Base plate PP1

••Heating element weld line, torn, ••Notch, sharp, ••MFR values, different, ••Crack in the heating element weld line by pressure overload, ••Polished sample through heating element weld line, ••Comparative examination

Membrane PP2 Figure 462, PP vibrating membrane 59 cm × 59 cm (damaged part, M = 8, AL), polished sample through a torn heating element weld line (red arrow). The vibrating membrane should keep the air pressure constant in a compressed air chamber. The unequally formed weld bead is conspicuous. This happened because during welding the MFR value of the membrane (PP2) is higher than in the base plate (PP1). The bead has a pronounced, sharp notch in the crack initiation area and a residual thickness of about 1.6 mm larger than in Fig. 463. The crack (blue arrows) was created by a pressure overload and notch effect in the transition from the weld edge to the membrane. The causes of damage were an equal temperature of the joint parts during welding, despite different MFR values, and a sharp notch at the weld edge (see also → MFR analysis).

376



Figure 463 ••Heating element weld line, good, ••Polished sample through heating element weld line, ••Weld beads comparison, ••Comparative examination

Base plate PP1 Membrane PP2

Figure 463, PP vibrating membrane 59 cm × 59 cm (good part, M = 8, AL), polished sample through a torn heating element weld line. A polished sample through the membrane cross-section shows a good heating element weld line (arrow). The weld bead is smaller than in Fig. 462 and the weld bead content of both joining partners is about equal. This was accomplished prior to joining with a slightly extended pressing time of the base plate (PP1) into the heating element so that the welding temperature and flowability were increased.

Figure 464

Figures & Text

••Socket welding, leaking, ••Welding, oblique

Figure 464, PB-T-piece with electrical socket (M = 1 : 1). The sawed socket welding shows a partially defective weld. Causes of damage were identified: the oxide layer of the joining partners was not mechanically removed as it should have been and the socket was obliquely welded to the pipe because the pipe axes were not aligned axially in the narrow shaft.

377



Figure 465 ••Electrofitting weld line, ••Molded part stresses are made visible, ••Electrofitting weld line with crack

Gaping crack after heating

Figure 465, PE100 gas pipe (M = 20, AL). A sample was cut out of the electrofitting weld line and a polished sample was manufactured with it. After a heating of the polished sample surface with a heat gun at 300 °C, a gaping crack (arrow), which exactly followed the weld line, developed. And a 10 micron thin section in the damage area resulted in an inconspicuous, homogeneous pipe structure (see also Fig. 466).

Figures & Text

Segment lateral surface

Pipe exterior Pipe interior Figure 466, PE100 gas pipe (M = 22, AL), detail from Fig. 465. The crack, which was opened by hand, has a normal stress center on its fracture surface, a crack, which is following the weld line (blue arrows), and no mechanical damage (scratches or cut grooves) on the pipe surface. According to our research, the crack developed during unwinding and intake of the long pipe from the ring collar into the pipe trench. The damage developed thus in the cooling phase by tensile and bending stresses in the weld line after an early dissolution of the pipe fixing during welding (see also Fig. 465).

378

Figure 466 ••Electrofitting weld line, PE100, ••Fitting weld line with crack, ••Crack in weld line through stresses, ••Pipe fixing, dissolved too early



Figure 467 ••Recrystallization in a pipe winding, ••Relaxation in the pipe winding, ••Crack, gaping, by resistant to unwinding, ••Pipe installation problems

Excavation pit

Cracks

Flanged steel pipe

Figure 467, PE63 gas pipe in a steel gas pipe DN100 (M = 1 : 1). At a 5 °C outside temperature, 70 cm were removed from the leaking steel gas pipe and a 23 m long PE black gas pipe with a yellow protective coat from a ring collar was inserted without guide rollers. After the installation, the PE gas pipe got a gaping crack. The causes of damage were bending and tensile stresses, winding resistance, which are high at 5 °C when installing in the excavation area due to shape changes and post-crystallization in the pipe winding (after 1 year of exposure), an additional lifting during inserting the gas pipe, and a deep notch through a sharp stone.

Figure 468 Weld line

Figures & Text

••Microvacuoles, ••Lack of holding pressure, ••Polished sample through friction weld line, ••Friction weld line with radial groove, ••Radial groove in friction weld line

Figure 468, ASA housing (M = 8, AL). A polished sample for the assessment of a friction weld line in the lower joint part shows a radial groove (left, near the middle of the figure) and microvacuoles (bright spots). The friction weld line is unobtrusively good. But the lower joining part is poorly manufactured and has many microvacuoles due to a partial lack of holding pressure. The barely recognizable radial groove fulfilled its purpose and reduced the leakage of welding material.

379



Figure 469 Extrusion direction

••Fracture sensitivity of a heating element weld line, ••Streaks, free of pigments in PE, ••Carbon black streaks in heating element weld line

Joining zone

Figure 469, PE heating element weld line (M = 15, DL). A 10 micron thin section through the weld line of two 30 mm thick PE plates that are welded together show parallel, white (nonpigmented) and black streaks (carbon black). Such strong inhomogeneities produce a high tendency to fracture in the joining zone when external forces also act in addition to the existing residual stresses in the semifinished parts.

Figures & Text

Figure 470 Welding bead

Figure 470, PP drinking water pipe (M = 18, DL-POL + -plate), 10 micron thin section. During joining of two PP pieces of pipe in the heating element welding process, a large welding bead with distinct shear zones at the edges developed through the outflowing plastic during the increase of the welding pressure.

380

••Heating element weld line with shear zones, ••Welding bead with shear zones



Figure 471 ••Heat-up time too short for PP heating element weld line, ••Heating zone is clearly visible, ••Heating element weld line, torn, ••Welding with dissimilar MFR values, ••Welding beads have the same size, ••Polished sample through heating element weld line

Crack

Heating zone

Figure 471, PP filter (M = 20, AL) with a crack next to the heating element weld line. Through the heating element weld line, a polished sample was made in the heating zone. The crack developed through the notch effect in the welding edge due to mechanical overload. It is noteworthy that the joint partners had unequal MFR values for design reasons. Nevertheless, the executing company managed a sufficient welding through differently adapted heating temperatures of the joint partners, as the weld beads prove, which are almost the same size. However, we still recommended a longer heat-up time, because the heating zone is only 1100 micron thick at the thinnest area.

Figures & Text

Figure 472 ••Weld line (V-notch) with cooling zones in trans mitted light, ••Contrast method DL, ••Welding factor 1 PP V-notch, ••Comparative examination

Figure 472, PP container weld line (M = 14, DL). An 8 micron thin section through the weld line shows, in normal transmitted light, a V-notch that is welded with a drawing nozzle. The weld layers of the V-notch have production-related cooling zones. But these are much more visible with a POL filter. In a tensile test it was proven that the weld factor surprisingly reached the factor of 1, although the structure is relatively inhomogeneous (see also Fig. 473).

381



Figure 473 ••Contrast method DL-POL for PP V-notch, ••Welding factor 1 of a good PP V- weld line, ••Comparative examination

Figure 473, PP container weld line (M = 18, DL-POL). It is the same weld line as in Fig. 472 but at a different location. When compared with Fig. 472, the superiority of the contrast procedure DL-POL (transmitted light polarization) becomes obvious because the spherulites, cooling zones, and the inhomogeneous structure are now clearly visible.

Figure 474

Figures & Text

CU heating oil

Insufficient welding

Figure 474, PE drinking water pipe (M = 12, AL) with electric socket. The end of the pipe with the electric socket was sawed off, halved, and one half of it was sanded, polished, microscopically examined, and photographed. The copper heating coil in the electric socket is heated in a current flow and the plastic becomes plastic. Usually the surrounding PE matrix is consequently expanding ring-like around the heating coil, and the resulting welding pressure welds the electric socket with the drinking water pipe. But that was not possible in this case because the electric socket was sitting crooked on the water pipe. The cause was a narrow, hardly accessible laying area, which is why the joint parts didn’t weld straight (not aligned) with the bending stress.

382

••Welding axes not aligned, ••Welding pressure in electric socket, ••Electric socket welding, faulty, ••Polished sample, ••Electric socket welding



Figure 475 ••Electrofitting weld line PB, poor, ••Pipe insertion depth, ••Polished sample through electric socket weld line, ••Weld line progress of electrofitting weld line

Pipe Collar bushing

Figure 475, PB electrofitting weld line (M = 8, AL). A polished sample, which gave good hints to the insertion depth and the weld line progress (arrows) between the collar sleeve and the pipe, was manufactured from the leaky weld line (see also Fig. 476).

Figure 476 ••Electrofitting weld line PB, poor, ••Delamination of electrofitting weld line

Figures & Text Figure 476, PB electrofitting weld line (M = 8, AL), detail from Fig. 475. The weld line between the collar sleeve and the polybutene PB pipe unexpectedly behaved brittlely in a tensile test (peel test) and delaminated with no obvious ductile areas.

383



Figure 477 Sample 1

Sample 2

••Weld line comparison of a good and fragile heating element weld line, ••Weld line influences, ••Weld bead differences

Figures & Text

Figure 477, PVC window weld line, fragile (M = 12, AL), weld line comparison of a good sample 1 with a bad sample 2. The weld beads of both samples have unavoidable voids (air or gas inclusions) and are in sample 1, 21% smaller than in sample 2. A 10 micron thin section through the two weld lines of samples 1 and 2 shows larger voids and pigment streaks in the weld line of sample 2. Noticeable in the fragile weld line of sample 2 (weld beads are breaking brittlely) were the larger voids and pigment streaks. But there are still more influences to consider in heating element weld lines: additives, heat-up time, joining force, gelation, recycling additives, residual moisture, and welding temperature.

Figure 478 ••Ultrasonic weld line PP, poor, ••Embedding in epoxy resin, ••Polished sample of PP

Figure 478, PP carburetor float ultrasonic weld line (M = 6, AL). For the microscopic examination of the weld line quality of two carburetor floats, two weld sections were embedded in epoxy resin EP and examined under a microscope, because no 10 micron thin sections were possible in its delivery state (see also Fig. 479).

384



Figure 479 ••Energy direction indicator, remains of, ••Seam offset at ultrasonic seam, ••Welding influences in the ultrasonic weld line, ••Weld line quality, ••Welding bead protrusion, one-sided, ••Ultrasonic weld line, poor

Welding bead

Figure 479, PP ultrasonic weld line, poor (M = 25, DL-POL). The microscopic examination of the weld line quality of the two carburetor floats, which are embedded in epoxy resin EP, was done with 10 micron thin sections (see Fig. 478). Residue of the energy direction indicator, an extremely one-sided protruding weld bead, an unwelded area of about one-third of the weld width and low seam offset, can be seen in the picture. For a remedy, the following was recommended: reduce the welding pressure and flatten the energy direction indicators toward the welding bead.

Figures & Text

Figure 480 ••Heating element weld line, unfavorable, ••Hot air treatment dissolves welding stresses, ••Polished sample, ••Weld line width, at least 10%

Figure 480, PE100 drinking water pipe with heating element weld line (M = 8, AL). For detecting the actual weld line width of the heating element weld line, a block ground sample was manufactured with SiC (silicon carbide) wet sandpaper, grit 1200, through the weld line. The block ground sample was carefully fanned with a heat gun at 320 °C until the weld stresses dissolved and stood out vividly. The hot air treatment then showed the actual width of the weld line, which should reach about 10% to 20% of the wall thickness at the narrowest point for good weld line strength. In this case, the weld line width was good, but the heat-up time and the joint pressure of both joint partners were a bit too high, because the weld beads are almost uniform but still quite large. Note: at a too-high joining pressure, there is a danger that too much heated molding compound is pressed out of the weld line and the colder areas of the joining partner will weld together.

385



Figure 481 ••Ultrasonic weld line for POM with low weld line strength, ••Ultrasonic welding parameters, compared

Figure 481, POM ultrasonic weld line (M = 20, DL-POL + -plate). The welding parameters were significantly greater than in Fig. 482 with 300 N welding force and 1.10 mm welding path, resulting in lower weld line strength.

Figure 482

Figures & Text

••Ultrasonic weld line for POM with good weld line strength, ••Ultrasonic welding parameters, compared

Figure 482, POM ultrasonic weld line (M = 20, DL-POL + ). In the welding parameters, the welding force was at 90 N and the welding path at 0.75 mm. At the same welding temperature compared to Fig. 481, the lower welding force was only 90 N instead of 300 N, and the lower weld path was 0.75 mm instead of 1.10 mm, resulting in a better weld line strength for polyoxymethylene POM.

386



Figure 483 ••Heating element weld line for PE, good, ••Polished sample through heating element weld line, ••Welding factor of 1 for PE heating element weld line

Figure 483, PE heating element weld line at a pressure pipe (M = 6, AL). The welding parameters were normal and the tensile test revealed weld strength of 1. This means that the weld line strength equal to the strength of the pipe.

Figure 484 ••Polished sample by a PP T-joint weld line, ••T-joint welding factor up to 0.95

Figure 484, PP T-joint seam (M = 6, AL). The welding parameters of the extrusion weld line are unremarkable. Mechanical load trials on different samples from the T-joint gave good weld line strengths, that is, the welding factors reached an average of 0.95.

387

Figures & Text

T-joint


LM Subchapter: Stresses

Figure 485 ••Isochromatics in SAN, ••Macromolecule orientations, ••Microcracks through wetting agent test

Figure 485, SAN cup (M = 18, DL-POL) with isochromatics (white arrows) and microcracks (black arrows) after a wetting agent test. The SAN cup was stored for 10 min at room temperature in n-propanol : toluene 1 : 5 and was then removed and examined under a microscope after 5 h of drying. Isochromatics are light refractions of macromolecular orientations, which are made visible in polarized transmitted light, and are produced by molded part stresses or rheological flow processes (see also → wetting test).

Figures & Text

Figure 486 Crack progress

Figure 486, PE100 gas pipe (M = 15, AL) with stress cracks in the cutting edge (pipe end) after flaming of the weld line using the flame of a Bunsen burner. The crack (arrows) followed exactly the left-widening weld line (see also Fig. 487).

388

••Flaming of PE100 with the gas flame of a Bunsen burner, ••Stress crack



Figure 487 ••Flaming with gas flame, ••Treatment with hot air with a gas flame, ••Air trapping in weld line, ••Stress crack

Gaping crack after heating

Weld line width

Figure 487, PE100 gas pipe (M = 15, AL), detail from Fig. 486 with a stress crack in the pipe end and inside the pipe. After gently flaming the weld line with a gas flame, a crack developed next to the weld line. The damage cause was an air inclusion, which was welded in during the welding process. The air inclusion, which is pressed flat through the welding pressure, had a weakening effect in the pipe cross-section. The crack became visible because the trapped air expanded during heating.

Figure 488

Figures & Text

••Gate ABS/PC with residual stresses, ••Wetting agent test, ••Pinpoint gate with wetting agent cracks

Figure 488, ABS/PC switch button, polymer blend (M = 18, AL), with wetting agent cracks. The pinpoint gate test showed, at a wetting agent test (also called stress test) after 15 min exposure at ambient temperature in toluene : n-propanol 1 : 3, a shrunken surface from significant residual stresses in the gate area. After removing the sample from the wetting agent bath, a long drying time, preferably overnight, makes sense so that the wetting agent can evaporate. The plastic swelling decreases, and eventually cracks will then be more visible.

389



Figure 489 ••Crack coloring with fuchsine, ••Stress cracks due to media influences

Figure 489, PA6.6 door handle (M = 22, AL) with stress cracks. The cracks were colored with fuchsine for contrast enhancement. Fuchsine, a red powder, can be bought from chemical distributors. It is well stirred in water or in alcohol (if compatible with the plastic) and applied with a cloth that has been soaked in it, and the excess is immediately wiped off. The fuchsine dispersion with good capillary action quickly penetrates into cracks. The damage was caused by media influences from the public (for example, hand perspiration, cream or perfume residues). A UV exposure in space by solar radiation could be excluded.

Figure 490

Figures & Text

••Expansion stresses in SAN, ••Insert (metal), ••Molded part stresses, ••Insert, ••Comparative examination

Figure 490, SAN socket in the base of a molded part (M = 9, DL) with pressed-in SAN collar sleeve. During cleaning in a dishwasher, cracks emerged in the socket after a few hours, and a part broke off. Then the pressed-in gray SAN collar sleeve with an injected metal shaft (insert) lost its hold. Damage causes: the relatively high temperature of 90 °C during cleaning resulted in a rearrangement of the macromolecules (tempering) so that the molded part stresses that froze in during production were released. The shrinkage of the socket onto the collar sleeve and the expansion stresses from pressing in the collar sleeve caused the cracks and the fracture (see also Figs. 491 to 493, → molded part stresses, and → insert).

390



Figure 491 ••Fracture after crack contamination, ••Comparative examination

Figure 491, SAN socket in the base of the molded part (M = 10, DL). During cleaning in a dishwasher for 24 h at 90 °C, a crack developed in the socket that led to the fracture, and a part of the socket broke (see also Figs. 490 to 493).

Figure 492 ••SAN aging, accelerated, ••Tempering, ••Comparative examination

Figures & Text Figure 492, SAN socket in the base of the molded part (M = 10, DL). From the base, the area of the socket has been cut out and measured for accelerated aging for 24 h in a hot air oven at 90 °C and stored for tempering (heat treatment). Figure 493 shows the result (see also Figs. 490, 491, and → tempering).

391



Figure 493 ••SAN aging, accelerated, ••Shrinkage, extreme, ••Tempering ••Comparative examination

Figure 493, SAN socket in the base of a molded part (M = 9, DL). After accelerated aging of the socket from Fig. 492 in a convection oven for 24 h at 90 °C, its internal face (1) is highly shrunken by 33.34%, and on its outer side, (2) by 58.34%. The high molding stresses, due to the manufacture of the socket, which were released as shrinkage during tempering were the main cause of crack formation and fracture of the socket (see Figs. 490 to 492 and → shrinkage).

Figure 494

Figures & Text

••Runner for a 16-cavity mold, overview

Runner, 16 fold

Figure 494, Runner in delivered state (n = 1 : 1, AL) with PC plastic rivets, made in a 16-cavity mold (see also Figs. 495 to 497).

392



Figure 495 ••Runner, 16-fold with vacuole

Figure 495, PC runner in its delivered state, 16-fold (M = 6, AL), detail from Fig. 494 with a vacuole in the flow path center of the runner (see also Figs. 494 to 497).

Figure 496

Figures & Text

••Deformation, PC rivets, ••Molded part stresses, ••Wetting agent test with toluene and n-propanol

Figure 496, PC runner in delivered state, 16-fold (M = 20, AL), detail from Fig. 494. A wetting agent test in toluene : n-propanol 1 : 5 after 15 min exposure at room temperature, especially in the runner center (Figs. 494 and 495), developed deformations on the rivet head edge by frozen molded stresses and a rough surface on the rivet surface (see also Figs. 494 to 497, → orange skin, and → wetting test).

393



Figure 497 ••Wetting agents test for PC with toluene and n-propanol, ••Surface roughness on the pinpoint gate

Figure 497, PC runner in delivery condition, 16-fold (M = 24, AL), continuation from Fig. 496. A wetting agent test (also called stress crack test) generated deformation due to frozen molded part stresses and an orange skin in the pinpoint gate area after 15 min exposure at ambient temperature in toluene : n-propanol 1 : 5 in the runner center (Figs. 494 and 495). The abnormalities found in the runner were a vacuole in the runner center, deformations on the rivet head edge, and orange skin on the rivet surface. This was due to a too-low molding compound temperature and a holding pressure that was dropped a bit early (see also Figs. 494 to 496, → molded part stresses, and → vacuole).

Figures & Text

Figure 498 ••Axial cracks, ••Media attack through drilling emulsion and glass cleaner, ••Check the media for their suitability, ••Overload cracks

Figure 498, PC glass holder nut (M = 9, DL) with cracks. On the extruded round material of the glass holder nut, an M10 thread was cut after machining on a lathe. A polished sample, manufactured through the thread, shows axial cracks, grown from the inside to the outside and overload cracks in the thread flanks. These arose as a result of media load from the drilling emulsion during thread cutting, a mechanical overload in use, and a newly used glass cleaner. The following recommendations were successful for future damage avoidance: the PC glass holder nut should be tempered at 80 °C for 4 h after processing and tightened with a torque wrench, and only suitability-tested media (drilling emulsion, glass cleaners) should be used (see also → wetting test, → sample preparation, machining, and → tempering).

394



Figure 499 ••Homogenization of PA, poor, ••Isochromatics, ••Notches in the waved pipe, ••Pigment streaks

Figure 499, PA electrical conduits (M = 15, DL-POL + ), brittle and broken. Causes were pigment streaks due to poor homogenization and notches in the bow of the corrugated pipe inside due to a too-late shaping. The isochromatics indicate high internal stresses because the electric conduit was embedded in epoxy resin for the thin section. Therefore, the thin section cutting forces are unlikely to be the cause of isochromatics, but instead macromolecule orientations due to production-related residual stresses.

Figures & Text

Figure 500 ••Normal stress center, ••Failure area

Figure 500, HDPE drinking water pipe 50 × 4.6 (M = 10, AL). The sawed fracture shows a fracture flank with a normal stress center under the microscope. The failure area (fracture start) is close to the middle of the pipe wall. Causes are often, as in this case, microfine particles (such as pigment conglomerates) that result in material failure due to mechanical force (for example, tensile stress or overpressure).

395


LM Subchapter: Spherulites

Figure 501 ••Giant spherulites in PP, ••Melting microscope table, ••Spherulite growth

Figure 501, PP spherulites (M = 100, DL-POL + ), 10 micron thin section with giant spherulites of up to 400 micron in diameter in polypropylene PP. They only become that large on a microscope melting table when the melt temperature is very slowly cooled down from its high temperature, degree by degree. The spherulites, which gradually grew in polypropylene PP, have an aster (flower) structure and are, according to our observation, the largest there is. In normal plastic processing, such giant spherulites are not expected.

Figure 502

Figures & Text

••Heating element weld line with PP spherulites, ••Extrusion, cold, ••Weld bead with pronounced shear zones, ••Spherulites in the weld bead

Figure 502, PP drinking water pipe 100 (M = 18, DL-POL + ), 10 micron thin section. When joining two pieces of pipe, a weld bead from plastic pipe material with sharp shear zones developed in the heating element welding process. The spherulites are only clearly visible in the weld bead, meaning, the PP drinking water pipe was extruded relatively cold.

396



Figure 503 ••Most homogeneous spherulite structure of PA6 there is (according to our experience), ••Marginal zone, poor in spherulites, is missing, ••Mold temperature influence

Figure 503, PA6 spherulites (M = 100, DL-POL + ). A 10 micron thin section in transmitted polarized light shows the most homogeneous spherulite structure that can be reached in a polyamide PA6 in a forming injection mold. This was only possible at an extremely slow cooling in the laboratory. At a mold temperature of 125 °C, no usual marginal zone developed, with a predominantly amorphous structure. While the large spherulites of the center of the wall decrease toward the marginal zone, they are however still clearly visible.

Figure 504

Figures & Text

••Coloration of PA, subsequently, ••Hot-cold mixture, ••Homogenization, poor, ••Spherulites, ••Spherulite streaks with notch effect, ••Mold filling, oscillating

Figure 504, PA molded part (M = 100, DL-POL + ), 10 micron thin section with a hot-cold mixing of the molding compound. When injecting a hot-cold mixture, which is poorly homogenized in the injection cylinder, spherulite streaks developed with a notch effect in the transition area with large to small spherulites (see also Fig. 505, → hot-cold mixture, → notch effect, and → spherulite streaks).

397



Figure 505 ••Coloration of PA, subsequently, ••Homogenization, poor, ••Spherulite streaks with notch effect

Figure 505, PA6.6 molded part (M = 100, DL-POL + ), 10 micron thin section with pigment and spherulite streaks. The molding compound was subsequently colored with a masterbatch but insufficiently homogenized, which is why pigment streaks developed. During injection, spherulite streaks developed that could be confused in appearance with a hot-cold mixture. At areas where many pigments were located, small spherulites grew, and where fewer pigments were located, large spherulites developed (see also Fig. 504, → spherulites, and → spherulite streaks).

Figure 506

Figures & Text

••Cracks, intergranular, due to spherulite growth

Figure 506, POM spherulites (M = 200, DL-POL + ), 10 micron thin section with intergranular cracks between the spherulites. See Fig. 507 for further explanation.

398



Figure 507 ••Microcracks in POM, intergranular, ••Holding pressure is too low, ••Shrinkage between the spherulites

Figure 507, POM molded part (M = 200, DL-POL + ) with brittle fracture. A 6 micron thin section in polarized transmitted light with -plate shows intergranular microcracks at the grain boundaries of the spherulites. This arose due to shrinkage between the spherulites because the density increased during the spherulite growth in each spherulite. The cause of the damage was a too-short-acting holding pressure because the gate froze due to a too-low mold temperature. Therefore, the molding material supply, which is necessary for shrinkage compensation from the residual mass cushion of the injection unit, was missing. Such POM molded parts are brittle and conspicuously break. If the holding pressure is dropped too early, intergranular cracks in a polyoxymethylene POM can also develop at a well-chosen mold temperature (that favors spherulite growth).

Figure 508

Figures & Text

••Amorphous structure for POM, instead of semicrystalline, ••Marginal zone, extremely poor in spherulites, ••Embrittlement

Figure 508, POM coupling (M = 30, DL-POL + ), 10 micron thin section through a fracture area with marginal zones, which are extremely poor in spherulites, up to 450 micron wide. Their content was 65% in the 1.20 mm thick cross-section. That means that 65% of the molded part cross-section was mostly amorphous instead of semicrystalline and was thus brittle. Damage cause was an extremely cold mold.

399



Figure 509 ••Molding compound, cold, ••Growth direction of POM spherulites, ••Mold, very cold

Figure 509, POM molded part (M = 100, DL-POL + ), 10 micron thin section. In the contact area of the cold mold surfaces, in the spherulite-poor marginal zones, (left in figure and Fig. 508), the spherulite growth declined. There, the warm molded part came in contact with the colder mold walls. Therefore, the spherulites grew toward the molded part center (right in figure), where the temperature is highest and acts the longest. The cause of the spherulite-poor marginal zones was a very cold mold and a cold molding compound.

Figure 510

Figures & Text

••Crack through the center of PP spherulites, ••Crack-splitting force divides POM spherulites

Figure 510, PP desalination plant (M = 150, DL-POL). A 10 micron thin section through the damaged area shows a crack in the semicrystalline polypropylene molded part. The crack runs partly through the spherulites and not, as may be expected, along the spherulite border zones. This proves that the splitting force of a crack can also split spherulites.

400


LM Subchapter: Over-injection

Figure 511 ••Surface error due to free-fall demolding, ••Orange skin, ••Over-injection, possible confusion

Figure 511, PBTB piston (M = 10, AL) with mechanical surface damage and over-injection. After opening the mold, the molded part dropped in free fall (free-fall demolding) into the lower collection basket, causing a mechanical surface defect (arrow 1). Furthermore, in close proximity, an orange skin structure and a small over-injection (arrow 2) can be seen. For demolding into a collection basket, the assembly line demolding is always more advantageous than a free-fall demolding because a free-fall demolding, as seen in the figure, can create mechanical surface defects and also molded part warpage. The cause for the over-injection (arrow 2) was accidental mold damage when setting up the mold (see also → over-injection).

Figure 512

Figures & Text

••Molding compound particles in LDPE, ••Molding compound residue transfer, ••Over-injection, ••Stretched tip

Figure 512, LDPE cable support (M = 12, AL) with over-injection and molding compound residue transfer. In an over-injection, the molding compound protrudes above the surface of the molded part (left in the figure) and therefore also above the originally forming mold surface. The stretched tip (on the right in the figure) developed due to molding compound residue transfer and the over-injection due to an unwanted mold dent (see also → dent, → molding compound residue transfer, and → over-injection).

401


LM Subchapter: Over-injection

Figure 513 ••Molding of PA6-GF30, poor, ••Orange skin structure, ••Over-injection, ••Processing, too cold, ••Mold marking, coarse, ••Mold aging, ••Mold change, subsequent

Figures & Text

Figure 513, PA6-GF30 armrest (M = 15, AL), freshly injected sample with over-injection, far away from the gate. The molded part has a coarse mold marking, sanding marks, and over-injection in the middle of the figure on the bottom. The poor impression in the left half of the figure and the orange skin in the middle of the figure prove a too-cold mold temperature (cold processing). After an examination that was initiated by us, the client admitted that because of a faulty temperature gauge, the molding compound temperature was too low. It also confirmed a rework on the mold (mold change). This is how bad a molded part surface can look after mold change, mold wear, or poor mold filling (see also → over-injection and → mold filling).

Figure 514 ••Injection burr with expensive rework, ••Injection burr due to mold breathing

Injection burr

Figure 514, PE expander handle (M = 20, AL). Into the rectangular cut-out (opening) in the expander handle, a snap hook with rubber bands should be snapped in during use. In this area, an injection burr formed (floating burr, webbing), which required a costly rework by hand. The cause was mold breathing due to a high injection pressure (see also → injection burr and → mold breathing).

402


LM Subchapter: Over-injection/Vacuoles

Figure 515 ••Injection burr of ABS, ••Mold impression, poor, ••Mold temperature, too low

Injection burr Figure 515, ABS siphon (M = 15, AL) with web in the lid recess, a defective demolding, and orange skin. Causes were too-high injection pressure into a too-cold mold. The high injection pressure caused mold breathing. Therefore molding compound emerged and formed an injection burr. The causes for the orange skin and the poor demolding were a too-cold mold temperature. Thus, the molding compound boundary layers in the too-cold mold solidified too early and could not adjust enough to the mold surface (see also → injection burr and → mold breathing).

Figures & Text

Figure 516 ••Sink mark after the removal of PE

Figure 516, PE door handle (M = 12, AL) with a large sink mark in the grip surface. Immediately after demolding, the dark sink mark (figure middle) could not be seen until later, after complete cooling. After grinding of the surface, as shown in Fig. 517, two inclined vacuoles were identified as damage causes.

403


LM Subchapter: Vacuoles

Figure 517 ••Vacuoles under the sink mark, ••Block ground sample of PE, ••Post-crystallization, ••Post-shrinkage, ••Wet sandpaper, grit

Figure 517, PE door handle (M = 12, AL). From the door handle in Fig. 516, a specimen was vertically sawed through the sink mark and roughly sanded with 220, 320, and 500 grit wet sandpaper. The block ground sample shows two vacuoles just under the sink mark. Causes of damage are the two vacuoles. They create shrinkage cavities after the completion of cooling and sink marks in the molding compound. But sometimes those sink marks become visible days later, when the shrinkage and the crystallization are completed.

Figure 518

Figures & Text

••Granulate examination for contaminants, ••Vacuoles in the granulate are harmless

Figure 518, PC granulate (M = 6, AL and also DL for brightening). For the examination of granulate, to determine whether foreign material or contaminants are present, approximately 100 g of a batch of granulate was spread out in one layer on a light plastic tablet and visually examined. Then a microscopic examination at 10x magnification of the screened, conspicuous granulates followed. In the present case only harmless vacuoles were found in the PC granulate but no impurities. The vacuoles are irrelevant here since they disappear in further processing of the granulates during injection molding or extrusion.

404



Figure 519 ••Dome crack in PBTP GF20, ••Molded part stresses

Dome base

Figure 519, PBTP GF20 housing (M = 12, AL) with gaping dome crack due to molded part stresses, that starts from the dome base up to almost the dome edge (left side of the figure; see also Fig. 520).

Figure 520

Figures & Text

••Expansion forces in PBTP GF20 dome, ••Large vacuoles, ••Microvacuoles, ••Polished sample, ••Screw expanding forces

Large vacuoles

Micro vacuoles Figure 520, PBTP GF20 housing (M = 20, AL). A polished sample parallel to the crack in Fig. 519 shows microvacuoles and large vacuoles in the crack initiating area of the dome base. The causes of damage for the dome crack are molded part stresses and expanding forces during thread cutting with a self-intersecting screw, in conjunction with other forces acting in use.

405



Figure 521 ••Molding compound flow of PA6.6-GF25, tough, ••Fiber glass influence, ••Plastic conducts heat poorly, ••Core, plastic, ••Vacuoles and tougher molded part flow due to glass fibers, ••Viscosity influence of glass fibers

Figure 521, PA6.6-GF25 housing (M = 25, AL) with vacuoles in the plastic core (center of the molded part wall). Plastic is a poor conductor of heat and remains warm the longest and therefore the longest plastic (viscous like honey) in the center of the wall. There the largest spherulites grow. The vacuoles developed due to a hindering of the glass fibers, a too-low mold temperature, and a resulting viscous flow of the molding compound (see also → molding compound flow, tough and → core, plastic).

Figure 522

Figures & Text

••Molding compound (AMMA), inhomogeneous, ••Holding pressure, dropped too early, ••Pigment streaks, ••Residual granulate addition, ••Vacuoles

Figure 522, AMMA holder (M = 8, DL). A 10 micron thin section shows vacuoles to 1.2 mm in length and an inhomogeneous molding compound with pronounced pigment streaks. The causes of damage were residual granulate addition and a holding pressure dropped early. AMMA is an acrylonitrile-methyl methacrylate.

406



Figure 523 ••Coloring of POM, subsequent, ••Homogenization, poor, ••Masterbatch coloring, ••Pigment streaks, striking, ••Giant vacuole

Giant vacuole

Figure 523, POM bearing shell (M = 50, DL), 10 micron thin section with an inhomogeneously colored molding compound (pigment streaks) and a large vacuole of 4500 micron in length. The damage causes were a subsequent coloring with masterbatch, a poor homogenization, and a holding pressure dropped too early. Normally, vacuoles (shrinkage cavities) have a rugged inner surface. But this rule does not apply so strictly for giant vacuoles.

Figure 524

Figures & Text

••Center vacuole in PA6.6-GF30, ••Lack of holding pressure, ••Pinpoint gate with center vacuole, ••Shrinkage adjustment is missing, ••Residual mass cushion is missing, ••Vacuole in the gate, due to a lack of holding pressure

Figure 524, PA6.6-GF30 ball cup (M = 20, AL). The pinpoint gate with center vacuole (arrows) shows a too-early dropped holding pressure. Justification: A vacuole (shrinkage cavity) always indicates a partial lack of holding pressure. Therefore, if shrinkage is already present in the gate or gate area there, it is evidence for a poor distribution of molding compound into the mold for shrinkage compensation. There are three reasons for this: the holding pressure time and thus the holding pressure are too short, the residual mass cushion in the injection unit is dosed too low or is missing, because the screw tip is sitting close to the cylinder, or no molding compound can flow through because the gate is frozen. Then, the mold temperature and/or the molding compound temperature are too low. In this case, the residual mass cushion was missing (see also Fig. 525, → holding pressure, and → vacuoles).

407



Figure 525

Pinpoint gate with center vacuoles

••Center vacuole in POM, ••Pinpoint gate with center vacuole, ••Shrinkage compensation is missing, ••Vacuole in the gate due to a lack of holding pressure, ••Mold temperature is too low

Figure 525, POM rod with center vacuole (M = 10, AL). The cause was a too-low mold temperature, whereby the gate was freezing too early and the holding pressure became ineffective despite the correct setting (see also Fig. 524, → holding pressure, and → vacuoles).

Figure 526

Figures & Text

Pressure side

Crack initiation center

Figure 526, PPE closing bracket (M = 18, AL). The fracture surface has many failure areas with crack initiation areas and vacuoles. The failure areas emerged in inhomogeneous areas of the plastic matrix and the cross-sectional weakening vacuoles due to a partial lack of holding pressure. Causes for a partial lack of holding pressure are poor-flowing molding compounds because they are, for example, too cold, highly filled, or reinforced; there is a long flow path in the mold or a too-short holding pressure time; the gate froze; or the mold temperature is too low.

408

••Crack initiation centers in PPE with failure areas, ••Vacuoles due to a lack of holding pressure



Figure 527 ••Marginal layer in POM, very cold, ••Marginal zone, poor in spherulites, ••Vacuoles in the fracture area

Figure 527, POM pipe holder (M = 25, AL), damage sample 2 from mold cavity number 6. First large spherulites developed in the molding compound in the wall thickness center, from the inside to the outside in the direction of the temperature decrease. Then, the very cold marginal layer with areas that are poor in spherulites developed after the contact with an extremely cold mold wall. Both terms “area, poor in spherulites” and “cold marginal layer” are summarized in semicrystalline polymers with the technical term “zone, which is poor in spherulites.” Such a distinct marginal zone is rare. In the examination through the fracture area, a 10 micron thin section showed large vacuoles up to 660 micron in length and an 825-micron-thick marginal zone, poor in spherulites, with a very cold, mostly amorphous marginal zone (see also → marginal zone, poor in spherulites).

Figure 528 ••Center vacuole in POM, ••Holding pressure dropped too early

Figures & Text Figure 528, POM torsion rod (M = 6, DL-POL). According to their own successful load tests, the customer demanded a microscopic assessment of the molded part quality, based on a 10 micron thin section. In the thin section, a center vacuole of 2130 micron in diameter is seen, but no spherulite-poor marginal zone was visible. Therefore the cause of damage was a too-early dropped holding pressure and no frozen gate due to a too-cold molding compound or mold temperature, as initially suspected (see Fig. 529 and → marginal zone, poor in spherulites).

409



Figure 529 ••Marginal zone, poor in spherulites, with 1300 µm extreme thickness

Figure 529, POM torsion rod (M = 6, DL-POL), damaged part, 10 mm thin section. After consultation with the client (see Fig. 528), the holding pressure time was increased, making the unwanted center vacuole disappear. However, it unfortunately decreased the mold temperature and a harmful spherulite-poor marginal zone with an extreme thickness of 1300 micron developed. As expected, this spherulite-poor marginal zone in subsequent load tests led to fracture due to embrittlement (see also Fig. 528 and → marginal zone, poor in spherulites).

Figure 530

Figures & Text

••Ring vacuole in a mass accumulation, ••Fracture, ••Design errors, ••Mass accumulation, ••Media influence

Figure 530, PA11 water filter (M = 10, AL), fracture piece with ring vacuole. The ring vacuole originated in an area of a relatively large wall thickness (mass accumulation). The causes of damage were obviously high bending stresses in the flange area that were not properly calculated (design error), and a transition, which has an almost completely nonrounded transition to the flange, with a mass accumulation (design error). Furthermore, a media influence of white, solvent-based ink stains is present. As confirmed by the client just beforehand, paint work had been done in the boiler room, which also housed the water filter. It was obvious that the handyman removed existing paint splashes with solvent (see also → design error, → mass accumulation, and → media attack).

410



Figure 531 ••Giant vacuole in PBTB, ••Cross-section weakening, ••Fibrils

Figure 531, PBTB piston (M = 9, AL). The fracture surface has an 8.2 mm long giant vacuole and fibrils (stretched tip) in the top left of the figure. Damage was caused by the effect of the cross-section weakening vacuole in the main load area of the piston (see also → fibrils and → vacuoles).

Figure 532

Figures & Text

••Microvacuoles in the gate area, ••Flowability, reduced, ••Glass fiber content, high, ••Holding pressure is dropped too early, ••Lack of holding pressure due to glass fibers

1 = Gate area

Figure 532, PP-GF40 rope drum (M = 30, DL), microvacuoles in the gate area (blurry, dark spots throughout the figure). Microvacuoles develop when the flowability decreases significantly in a cold mold and the holding pressure is no longer effective due to the freezing gate. In the example, the holding pressure was dropped too early, the high fiber filling of 40% causing the lack of holding pressure through a reduced flowability. The microvacuoles were only visible in the gate area after the entire sample was illuminated with a strong light source (see also → microvacuole and → holding pressure).

411



Figure 533 ••Marginal zones in POM, unequal, ••Residual mass cushion for shrinkage compensation was ineffective, ••Vacuoles, ••Mold halves are not equally heated

Figure 533, POM holder (M = 25, DL-POL). A 10 micron thin section near the fracture shows vacuoles that are up to 480 micron in size as well as large and unequal marginal zones that are low in spherulites. The marginal zones show an unequal heating of the mold halves. The left half was much warmer and the right one was much colder. There, the pinpoint gate froze. Therefore, the holding pressure was not able to press more molding compound from the residual mass cushion into the mold for shrinkage compensation.

Figure 534

Figures & Text

••Giant vacuole due to a lack of holding pressure, ••Mass accumulation, ••Holding pressure, path-dependent, ••Marginal zone, barely noticeable, ••Residual mass cushion for shrinkage compensation was ineffective, ••Mold halves, equally heated

Figure 534, POM bolt (M = 15, DL-POL + ). The 10 micron thin section has a giant 7.3 mm wide vacuole and barely recognizable spherulites-poor marginal zones. These prove a good and uniform heating of the mold halves. Hence the pinpoint gate did not freeze too early. The cause of damage was therefore a path-dependent holding pressure that was dropped too early. The big vacuole originated in the large wall thickness (mass accumulation) because no molding compound from the residual mass cushion for shrinkage compensation could be pressed into the mold.

412



Figure 535 ••Glass fibers in PPS GFM, unwetted, ••Focusing onto the vacuoles base, ••Vacuole and microvacuoles in the fracture area

Vacuole

Inner surface

Figure 535, PPS GFM pipe sleeve 18 mm (M = 30, AL), damaged part with vacuoles in the fracture area. In the present case, PPS GFM was a reinforced polyphenylene sulfide with a high fiber and mineral content. Fine microvacuoles (hole-like structures) can be seen in the foreground, unwetted exposed glass fibers can be seen in the 2.1 mm large vacuole (arrows), and small microvacuoles can be seen in the background of the vacuole. The damage causes were a too-low mass and a high glass fiber temperature and mineral content, which reduce the flowability. When focusing on the vacuole base, the molded part surface in the figure blurred due to the height difference in the fracture path (see also → flowability, reduced and → vacuole).

Figure 536

Figures & Text

••Center vacuole in a mass accumulation, ••Fracture area with center vacuole, ••Mass volume and shrinkage, ••Core, plastic

Figure 536, PC-molded part (M = 20, AL), damaged part with center vacuole in the fracture area. With increasing wall thickness (mass accumulation), the volume of the plastic shrinks more. Therefore, a large vacuole developed in the 8 mm thick mold wall, due to a too-short holding pressure time. The larger the mass volume, the longer the core stays plastic due to its heat insulating effect and has more time to shrink. Therefore, large cross-sections usually have larger vacuoles. To avoid that, the holding pressure time should be longer (see also → core, plastic and → center vacuole).

413


LM Subchapter: Burning

Figure 537 ••Diesel effect on PA6 GF30, ••Conveyor belt demolding is better than free-fall demolding, ••Mold venting, poor

Figure 537, PA6 GF30 housing bridge (M = 10, AL), freshly injected part, with burnt molded edge due to a diesel effect (red arrows) and a molded part fracture during demolding (blue arrows). A diesel effect arises due to the compression of trapped air in the mold at temperatures up to 1500 °C or at too-rapid injection at an insufficient mold venting. And a free-fall demolding caused the molded part fracture. A conveyor belt demolding would be recommended (see also Fig. 538, → conveyor belt demolding, → diesel effect, → ventilation, and → free-fall deformation).

Figure 538

Figures & Text

••Diesel effect for PA6 GF30, ••Molded part edge, burnt

Figure 538, PA6 GF30 housing bridge (M = 25, AL), detail from Fig. 537 with a burnt molded part edge caused by trapped, highly compressed air (diesel effect). The trapped air hindered the complete wetting of the mold surface through the molding compound (see also → mold marking).

414


LM Subchapter: Burning/Comparison

Figure 539 ••Burn streaks in the gate area, ••Gate with orange skin

Figure 539, ABS board, bottom (M = 10, AL). The burn streaks (left arrows) in the gate area developed due to a damaged molding compound in so-called “dead spots,” and the orange skin (right arrows) resulted from a too-low mold temperature. “Dead spots” are areas in the injection unit or mold in which the molding material lingers for an extended time and can therefore be damaged by heat (see also → orange skin and → overheating, thermal).

Figure 540

Figures & Text

••Examination, comparing, of conveyor belts made of PVC in polarized transmitted light, ••Blister bag packaging, ••Masterbatch change, ••IR and DSC analyses, ••Protection claim

Figure 540, PVC conveyor belts (M = 8, DL-POL). A comparative study between two PVC conveyor belts with electric resistances for a fully automatic soldering machine. The right conveyor belt tore off frequently. Based on the difference in color under polarized light (transmitted light with polarizer) between the right belt (defective part) and the left belt (good part), a contractually unauthorized masterbatch change was visible. This statement, which was easily found under the microscope, was confirmed by thermal analyses (IR and DSC analyses). The supplier of our client claimed, unflinching and unqualified, that the specified masterbatch quality was present (protection claim). But a good quality controller confirms, after a short examination, just as unflinching, his/her own opinions. Another report, issued to the client by another testing laboratory, reinforced our statement (see also → examination, comparing).

415


LM Subchapter: Comparison

Figure 541 ••Examination, comparing of PA-PTFE in incident light, ••Charge change, ••Top secret investigation

Figure 541, PA-PTFE piston ring (M = 10, AL), polished sample of sample 1. After a change of charge, the polished samples of sample 1 (good part) and sample 2 (broken damaged part) were evaluated in a comparative examination (see Fig. 542). The comparison shows clearly that the same charge was not used, as claimed, but a new charge of modified ingredients was used (see also → examination, comparing).

Figure 542

Figures & Text

••Examination, comparing, PA-PTFE in reflected light, ••Batch change, ••Top secret investigation

Figure 542, PA-PTFE piston ring (polymer mixture, M = 10, AL), polished sample of sample 2 (broken damaged part). Sample 2 shows red-brown particles in the matrix in comparison to sample 1. These were accepted by the client as the damage cause. The simple microscopic evidence that a masterbatch change was present was sufficient for them. They did not give the slightest information on the present case, although our institution was legally obliged to absolute neutrality, and was paid immediately for the figure report without comment. This event was a typical example of a “top secret investigation” without explanations and advice on the damage. Therefore, we never knew what we had examined (see also Fig. 541, → matrix, and → examination, comparing).

416



Figure 543 ••Examination, comparing, ••Electrofusion welding, ••Grooves due to scraping, ••Tear or cut?, ••Clarify the question of guilt, ••Duty of care, neglected

Figure 543, PE100 gas pipe leaks and has cracks in the electric socket area (M = 10, AL). It was claimed that the pipe manufacturer was to blame for the crack. However, as a loss adjustment revealed, the surface of the pipe was first damaged with a pipe cutter (cutting damage) and then the oxide layer was scraped off. The cutting damage had scraped off cutting edges and caused the subsequent crack due to the notch effect at a deflection of the pipe. Incredibly, the pipe layer built in the gas pipe, although he must have noticed a resistance at the “crack” (cutting damage) during scraping. The causes of the leak were cutting damage with scraped edges and a poorly welded electrical socket. Proof of this was given by examinations on another pipe (Figs. 544, 545), because the damaged pipe (as evidence) could not be changed. The pipe layer was to blame for the damage, not the pipe manufacturer. Thus, for the legal dispute it was unimportant whether a crack or a section was the cause (see also → scrape the oxidation layer and → damage reenactment).

Figure 544

Figures & Text

••Examination, comparing, ••Grooves due to scraping, ••Tear or cut?, ••Damage reenactment, ••Cutting damage

Sharp edge

Figure 544, PE100 drinking water pipe (M = 10, AL). The damage in Fig. 543 was reenacted on another PE100 pipe end. First, the pipe surface was scraped off, and then cutting damage was added with a pipe cutter. The grooves, which formed during scraping with a scraper, could not scrape off the cutting edges of the subsequent scrape injury, as in the case of damage. The cutting edges remained sharp. This means that no jerky resistance could be felt during scraping, as in the case of damage, because the cutting damage occurred later (see Fig. 545).

417



Figure 545 ••Examination, comparing, ••Grooves due to scraping, ••Crack or cut?, ••Damage reenactment, ••Cutting damage

Flattened edges

Figure 545, PE100 drinking water pipe (M = 20, AL). To reenact the damage (Fig. 543), the other end of the pipe (Fig. 544) was used, and cutting damage on the pipe surface was first created with a pipe cutter and then scraped off with a scraper. During the subsequent scraping and passing over the cutting damage, a significant and jerky resistance could be felt when the cutting edges were flattened. There, a quiet sound could be heard and the straight line of the cut damage changed its appearance, similar to the damaged pipe in Fig. 543 (see Fig. 544).

Figure 546

Figures & Text

••Examination, comparing, of a paint surface, ••Contrast method, choose correctly, ••Particles on the paint surface

Figure 546, Painted surface (M = 50, AL) with paint defects. A comparison with Fig. 547 shows that a properly selected contrast method provides more information. With the conventional reflected light method AL, only particles of different sizes are visible on the surface.

418



Figure 547 ••Examination, comparing, of a paint surface, ••Contrast method, correctly chosen, ••Paint defects, ••Particles are top-coat delaminations, ••Burn streak under the paint

Figure 547, Painted surface (M = 50, AL-DF) with paint defects, detail from Fig. 546 for comparison. A properly selected contrast method provides more information. In a study of plastic surfaces, the reflected light dark-field AL-DF method usually provides more information than the ordinary reflected light method AL. The particles in Fig. 546 are now recognizable as brittle detachments of a transparent topcoat (see also → contrast methods and → painting error).

Figure 548

Figures & Text

••Examination, comparing, ••Crack or cut?, ••Crack due to overload, no cut

Figure 548, PVC water bed sheet (M = 30, AL) with a leaking damage area. Our client suspected a crack as a damage cause. For a comparative examination, to see whether the damage was actually caused by a crack as the counterparty to our client claimed, the crack flanks were bent in a 180° fold and were compared with an intentionally created scalpel cut (Fig. 549). The microscopic examination of the leak showed a rough textured surface on the supposed crack flanks.

419



Figure 549 ••Examination, comparing, crack or cut?, ••Scalpel cut, intentional

Figure 549, PVC water bed sheet (M = 30, AL). For comparison with the damage area in Fig. 548, an intentionally created scalpel cut was bent to 180° so that its cutting edges were visible. When clearly visible, the cutting edges are smooth and not rough textured, as in Fig. 548. Therefore, the cause of the damage was an overload crack caused in use (such as by pointed pressure load) and certainly not cutting damage, as suspected by the client.

Figure 550

Figures & Text

••Polished sample, car cooler, comparison

Figure 550, PA6.6-GF30 cooler (M = 6, AL), alleged good part with a vertical polished sample through the subsequent damage area (leak, as in the damaged part in Fig. 551). The cooler is still sealed but shows a strong pinching of the rubber seal (arrows) between the metal claw and the molded part edge with vacuoles.

420



Figure 551 ••Polished sample, car cooler, comparison, ••Molded part stresses, ••Shear force influence, ••Deformation, permanent

Figure 551, PA6.6-GF30 cooler (M = 6, AL), damaged part. A vertical polished sample was made through the damage area (leaky area). The permanent deformation of the PA6.6-GF30 molded part edge in the direction of arrow 2 proved that molded part stresses, caused by manufacture, are present. In addition, in the molding of the metal claw (arrow 1), the pressing force of the rubber seal (Fig. 550) acted in the same direction against the molded part edge (see Fig. 550). The damage causes for the leaking cooler area were thus the shear force that is generated by the metal claw and production-related molded part stresses in the plastic material.

Figure 552

Figures & Text

••Design notes through assembly, ••Expanding stresses, ••Assembly of the single parts provides more insights, ••Polished sample shows part tolerances, ••Regranulate parts, unwanted

Figure 552, PC coupling (M = 6, AL), damaged part. After a microscopic examination of the delivered items (pin and pin acceptance), they were assembled for further findings, sawed through the middle, ground, and polished. The resulting polished sample showed the part tolerances in the interaction, unwanted regranulate parts, and an added regranulate content of 6% for cost savings (granulated gates). Often such simple polished samples result in important information for the construction and load. However, the major cause of the damage was a too-close tolerance between the pin and the pin acceptance because it caused a strong expanding stress.

421



Figure 553 ••Examination, comparing, contrast method of PVC with different contrast methods, ••Ca particles (calcium particles)

Figure 553, PVC pipe (M = 25, DL), damaged part. A 10 micron thin section through the damaged area in transmitted light only shows inconspicuous fine, gray pigment conglomerates that could not cause the damage. But in connection with a polarizer in polarized transmitted light, a large amount of strikingly lighter Ca particles (calcium particles) were then visible (see Fig. 554).

Figure 554

Figures & Text

••Examination, comparing, of PVC with different contrast methods, ••Ca particles (calcium particles)

Figure 554, PVC pipe (M = 25, DL-POL), damaged part. A 10 micron thin section through the damaged area shows a comparison with the many bright Ca particles (calcium particles) in Fig. 553 that only became visible in polarized light. Up to 20% calcium may be added to the PVC drinking water pipes. This improves the rigidity and sliding properties but can have a negative influence on the pipe strength when the calcium content becomes too large.

422



Figure 555 ••Examination of PVC with different contrast methods (AL-DIC), ••Particle, close to the crack

Figure 555, C-PVC drinking water pipe DN 20 (M = 100, AL-DIC). A polished sample near a damaged area with cracks in incident light differential contrast AL-DIC clearly shows particles without using a lambda plate. For comparison, the same area in reflected light differential contrast AL-DIC with a lambda plate is shown in Fig. 556.

Figure 556

Figures & Text

••Examination of PVC with different contrast methods (AL-DIC + ), ••Particle, close to the crack, ••Combine contrast methods

Figure 556, C-PVC drinking water pipe DN 20 (M = 100, AL-DIC + ). The same polished sample from Fig. 555 shows, in a comparison with a reflected light differential interference contrast with -plate, a different particle color in the crack vicinity but provides no further insights in this case. Nevertheless, in a microscopic examination that does not provide a clear result, the testimony of various contrast methods, even with seemingly nonsensical combinations, should be tested (see also → combine contrast methods).

423


LM Subchapter: Damage

Figure 557 ••Comparative examination, ••LDPE stretch film with hole or stab injury?, ••Winding film

Figure 557, LDPE stretch film 25 micron (M = 25, AL) with a hole in the outermost first winding layer. A hay bale was wrapped with 20 film layers of LDPE stretch film. During exposure a hole developed at the bottom of the hay bale with decreasing diameter, reaching from the first outermost winding layer to the 10th winding layer. Therefore, the hole in the first film layer is significantly larger than the hole in the 10th film layer. To clarify the issue, the client wanted to know if the damage was due to a pitchfork or a bird of prey.

Figure 558

Figures & Text

••Comparative examination, ••LDPE stretch film with stab damage, ••Hole edge in LDPE, frayed, ••Winding film

Figure 558, LDPE stretch film 25 micron (M = 25, AL) with a hole in the 10th winding layer. The LDPE stretch film on the bottom of a hay bale, wrapped with 20 layers of film, had a hole up to the film of the 10th winding layer. The frayed edges indicate a dull, mechanical damage from the outside, such as due to a thin but blunt object. A sharp one would have left sharp-edged holes. Therefore, in our opinion (contrary to the assumption of the counterparty), the perforations in the stretch film of about 2 mm in diameter are not stabbing damages of a pitchfork or a bird of prey because the hole edges have frayed, ductile stretching. A pitchfork or a bird of prey would have left major injury (see also Fig. 557).

424



Figure 559 ••Erosion, worm-like, into the inner pipe surface, ••Cavitation, ••Rust deposits, brown, ••Sand grain erosion

Figure 559, PVC pipe ∅ 150 (M = 1: 1), damaged part. The examination of the removed, leaking damage area created worm-like erosion on the inner surface of the pipe and brown rust deposits. Furthermore, fine sand residues were found. Causes of damage: The damage area was in the area of a pipe bow with a reduced withdrawal. And the rust deposits probably formed during previous repair work due to an unwanted intrusion of rust or metal chips from the municipal water line. The penetrating sand grains were obviously the cause of the deep erosion. When water flowed through (a maelstrom), this rubbed repeatedly over the same area and penetrated the pipe wall with time (figure, top right). The erosion in the figure is an example of cavitation, erosion due to grains of sand and water (see also Fig. 564).

Figure 560

Figures & Text

••Ejector load, unfavorable, ••Ejector marking, double, ••Demoldability, poor, ••Hairline crack, brittle

Gate Ejector mark

Figure 560, PBT windshield wiper (M = 6, AL). The brittle fracture developed from a brittle hairline crack (dark blue arrows) and ran through the gate and through the double ejector marking (light blue arrows). The causes of damage were a too-cold mold temperature, an unfavorable ejector load close to the gate, and a poor demoldability. Because the molded part was hard to demold, the double ejector marking developed due to a repeated ejection.

425



Figure 561 ••Block section in PBT/PC, ••Microscopy with deeply oblique incident light, ••PBT particles, torn, ••Polymer blend, physical, ••PBT polymer mixture with PC

Figure 561, PBT/PC housing (M = 50, AL-DF) with brittle fracture. The 10 micron block section shows in the area of a brittle fracture, a homogeneous but rough distribution of the PBT particles that are physically integrated into the PC matrix. Soft PBT particles have been found in the depressions (the dark spots, which are not raised areas) that were torn out during cutting. The image was done with a so-called gooseneck cold light source and deeply oblique incident light. PBT/ PC is a physical polymer blend of polybutene terephthalate PBT and polycarbonate PC.

Figure 562

Figures & Text

••Media attack on PVC, drop-like, ••Grooves with raised edges, ••Damage, mechanical

Figure 562, PVC pipe (M = 29, AL). The pipe had mechanical damage with ejected raised edges in the surface. This damage was created by a sharp-edged metal edge that tore plow-like scratches with raised edges into the soft PVC compound. A drop-like media attack of unknown type and origin created the yellow dots. One of the yellow dots had a partial peripheral edge tear.

426



Figure 563 ••Examination, comparative, of a cutting injury in PIB, ••Cutting grooves due to a carpet knife

Figure 563, PIB film (M = 31, AL) with cutting damage. Because carpet knives are used in the processing of the film, the client suspected cutting damage due to a carpet knife. This was confirmed by our examination. The incision was made in the top right of the figure from below and then continued to the bottom right. The cutting grooves of the carpet knife are clearly visible in the area of the incision and cut continuation. A crack that had become a fracture would not have left such lines with a spontaneous change in direction in the crack edge. In case of doubt, a → damage reenactment is always recommended.

Figure 564

Figures & Text

••Cavitation areas in PP

Figure 564, PP membranes for the production of fruit juices (M = 15, AL) with cavitation areas. To press juice from a fruit pulp, highly compressive pressure is required. These strong fruit juice flows caused cavitation (erosion) in the PP membrane. Note: When pressing fruit juices, very high voltages can also be caused by fluid friction.

427


LM Subchapter: Reinforcement

Figure 565 ••Comparative examination, ••Polished sample through PF-GF-Cu with glass fiber strands and copper wires

Figure 565, PF-GF-Cu clutch plate (M = 10, AL), good part. The microscopic examination was carried out in comparison with the damaged part in Fig. 566. A radial polished sample through the clutch plate showed the distribution of glass fiber strands and copper wires (dark spots). The copper wires in a glass fiber strand were always in pairs and perpendicular to the plane of the polished sample surface to remove the heat that develops during braking.

Figures & Text

Figure 566 ••Comparative examination, ••Polished sample through PF-GF-Cu with glass fiber strands and copper wires, ••Application error, ••Glass fiber fabric, ••Crack in the border area, ••Design modification, unauthorized

Internal crack

Torn out surface Figure 566, PF-GF-Cu clutch plate (M = 10, AL), damaged part. A radial polished sample through the clutch plate shows a different distribution of glass fiber strands and copper wires than in the good part (Fig. 565): a broken surface and an inner crack. Such cracks can also be found in other polished samples in other places. The copper wires are all located outside of the glass fiber strands. They run parallel to the polished sample surface plane and the Cu wires run perpendicular to that. The cause of damage was thus based on a contractually improper design change by the manufacturer without consultation with our client. And the clutch plate failed prematurely due to the resulting loss of strength. As we found out, unfortunately no durability testing was done after the improper design change.

428


LM Subchapter: Reinforcement/Warpage

Figure 567 ••Talc conglomerate in PP T40 to 62 micron, ••Comparative examination

Eroded surface

Figure 567, PP T40 push rod with 40% talc (M = 200, DL). The broken damaged part, in comparison with a reference sample submitted by the customer (good part), had larger talc conglomerates of up to 62 micron in the tension zone of the flexurally stressed push rod. They were only up to 45 micron in size in the good part (figure not shown). The surface is also significantly more ripped than in the good part due to the cutting force of the microtome. Obviously, the larger talc conglomerates weakened the cross-section and thus caused the fracture.

Figure 568

Figures & Text

••Examination, comparing ••Molded part stresses in PBT T40, ••Shrinkage, ••Temperature, uneven, favoring warpage

Deflection

Figure 568, PBT T40 lid, 40% talc-filled (M = 1 : 1), in delivered state with molded part stresses. The molded part stresses, which are unavoidable in manufacture, can lead to warpage in the molded part due to volume shrinkage. Furthermore, it can lead to crystallization and post-crystallization during cooling, especially at a too-cold processing. The resulting molded part stresses are then unequally large, depending on the size of the mass accumulation and complexity of the design. The cause of the warpage here was an unequal temperature of the mold halves. The warmer mold half favored a stronger crystallization (see also Fig. 569, → molded part stresses, → mass accumulation, → post-crystallization, and → warpage).

429


LM Subchapter: Warpage

Figure 569 Bulge

••Examination, comparing, ••Bulge (warpage) for PBT T40, ••Molded part stresses, ••Warpage

Figure 569, PBT T40 lid, 40% talc-filled (M = 1 : 1), lateral view of Fig. 568 after hot treatment. After 5 hours at 95 °C tempering in a convection oven, the lid developed a surprising bulge (warpage) due to released molded part stresses in the opposite direction. The warpage was created due to molded part stresses that were caused by cold processing and too-early demolding in free fall. A conveyor belt demolding would have been gentler (see also → conveyor belt demolding, → free-fall demolding, and → tempering).

Figure 570

Figures & Text

••Aging resistance and warpage of ABS, ••Molded part stresses, ••Tempering, ••Heat exposure in a convection oven

Figure 570, ABS first aid kit (M = 1 : 1) after 72 h of heat treatment at 100 °C in a convection oven as a test for later suitability in the application. This temperature corresponded to the temperatures on dark surfaces in cars and led to strong warpage of the lid toward the gate due to shrinkage. The damage was caused by high molded part stresses. The first aid kit could then no longer be opened. Molded part stresses are unavoidable, especially in cold processing, and can lead to warpage. They depend on the complexity of the design and arise through volume shrinkage, crystallization, and post-crystallization during cooling and after. A high injection pressure (molecular orientation) or high holding pressure (especially when long-acting) has a bad influence. Molded part stresses reduce the aging resistance and complicate further processing, for example, when gluing and painting (see Fig. 571, → molded part stresses, and → warpage).

430


LM Subchapter: Warpage

Figure 571 ••Residual stresses of the molded part in an ABS first aid kit, ••Molded part stresses, ••Tempering, ••Warming in a convection oven

Figure 571, ABS first aid kit, bottom (M = 1 : 1). The high molded part stresses caused strong warpage in the lid and bottom toward the gate due to heat treatment for 72 h at 100 °C (see Fig. 570). After heat treatment in a convection oven, close to the glass transition temperature and with daily warpage control, the location and size of the molded part stresses became clearly visible. They cause shrinkage especially with a larger wall thickness (mass accumulation). And the higher the molded part stresses, the greater the shrinkage and warpage (see also → mass accumulation and → heat treatment).

Figure 572

Figures & Text

••Sink marks in CP, large, ••Molded part shrinkage, ••Holding pressure time too short

Sink mark

Figure 572, CP bolt (M = 6, AL) with large sink marks. Cause was massive molded part shrinkage by a lack of tracking of the molding material from the residual mass cushion in the injection unit. That means the screw came in contact with the cylinder tip before mold filling was completed. Too-short holding pressure time can also lead to molded part shrinkage at the surface (see also Fig. 573).

431


LM Subchapter: Warpage/Mold

Figure 573 ••Sink marks in PA11, ••Molded part shrinkage, ••Lack of holding pressure, partial

Sink mark

Figure 573, PA11 clip (M = 6, AL) with sink marks. The cause of damage was a molded part shrinkage caused by a partial lack of holding pressure in a mass accumulation in the area of the struts (see also Fig. 572 and → mass accumulation).

Figure 574

Figures & Text

••Molding compound PA, too tough, ••The flow path is not reached, ••Mold filling, poor

Poor mold filling Figure 574, PA bearing support (M = 6, AL) with poor mold filling at the flow path end. Because the molded part compound cooled down more and more toward the flow path end and became more viscous, it could not fill the mold cavity in the mold. Cause was (as usual) a too-low mold temperature, which should be set somewhat higher especially with long and narrow flow channels. But a too-low molding compound temperature and too-slow injection can produce such an error (see also → mold filling).

432


LM Subchapter: Mold

Figure 575 ••Dome fracture for PP-GF40, ••Flowability is too low, ••Molding compound temperature, too low? ••Examination termination, ••Mold wetting, poor, ••Mold temperature too low?

Poor mold wetting

Figure 575, PP-GF40 rope drum (M = 6, AL) with poor mold wetting in the dome fracture area (arrows). Cause was probably a too-low molding compound temperature, which decreased the flowability in the mold in the damage area. This statement via the phone satisfied the client, and he asked for the termination of the examination (examination termination) for cost reasons. A thin section would have delivered more results, whether the mold temperature is too low or granulate residue, pigment, or spherulitic streaks were involved in the fracture (see also → mold wetting).

Figure 576

Figures & Text

••Orange skin in ABS/PC, ••Polymer blend, ••Mold impression, poor

Figure 576, ABS/PC housing, polymer blend (M = 6, AL). The left hinge lever has a poor mold impression on the molded part surface and an orange skin due to too-cold processing during injection. ABS/PC is a polymer blend of acrylonitrile butadiene styrene copolymer ABS with polycarbonate PC (see also → orange skin, → processing, good, and → mold impression).

433


LM Subchapter: Mold

Figure 577 ••Molding compound transfer in PPS, ••Mold filling, insufficient

Figure 577, PPS lid (M = 18, AL). The molded part surface shows an insufficient mold filling (or mold wetting) with a rough surface, as in a material residue transfer. These are molding compound residues that are adhering to the mold from the previous shot (arrows; see also Fig. 578, → sequence shot, → material residue transfer, and → mold filling).

Figure 578

Figures & Text

••Molded part surface, open, ••Web on the ejector, ••Mold impression, poor

Molded part surface, not closed Bridge Web

Figure 578, PPS lid (M = 30, AL). This detail from Fig. 577 shows an open molded part surface at the transition from the bridge to the lid through inclusion of air, a reduced → molding compound flow, and a → web at the → ejector marking.

434


LM Subchapter: Mold

Figure 579 ••Flow path end in cold ABS/PC molding compound, too cold, ••Molded part wall, not fully injected, ••Polymer blend, ••Mold wetting, poor, ••Mold temperature, too low

Poor injection

Figure 579, ABS/PC door handle (M = 15, AL), polymer blend with not fully injected molded part wall. This was due to a too-cold molding compound on the flow path end in the mold because the measured mold temperature was only 40 °C, but also the verified molding compound injection temperature in the injection cylinder was about 10 °C too cold.

Figure 580 ••Holding pressure, dropped too early, ••Mold filling, poor

Figures & Text Figure 580, POM gear wheel (M = 10, AL) with poor mold filling (mold wetting). The molded part surface is poorly molded because not enough molding material got into the mold and the second and third gear tips from the right both show a flow front. This was due to a too-cold mold temperature and additionally a too-early dropped holding pressure (see also → holding pressure).

435


LM Subchapter: Mold

Figure 581 ••Cold-flow front in ABS/PC, ••Questions to the customer for self-protection, ••Polymer blend ABS/PC, ••Mold wetting, poor

Figure 581, ABS/PC recessed handle, bottom, polymer blend (M = 12, AL). At the bottom, a cold-flow front (cold flow) was created due to poor mold wetting (arrows). Attention: a subsequent dirty mold change can also simulate such errors through inaccurate work. Therefore, conscientiously study and question the client prior to the report release (see also → cold flow and → mold wetting).

Figures & Text

Edge

Missing edge

Cold-flow line

Figure 582, PA6 gear wheel (M = 6, AL), damaged part. The gear wheel worked sluggishly and with high operating noise in the gear rim (Fig. 583). The client asked us to find the causes. As the microscopic examination revealed, the gear wheel had a cold-flow line (blue arrow) as well as sharp and deformed gear edges (green arrows). And due to a dividing error, the gear wheel jammed in the gear rim, whereby the gear edges were mechanically deformed (see also Fig. 584, → cold-flow line).

436

Figure 582 ••Mechanical deformation of PA6, ••Dividing error, ••Gear wheel with deformed gear edges


LM Subchapter: Mold

Figure 583 ••Cold-flow area in PA6, ••Orange skin, ••Processing, too cold, ••Gear rim with poor impression

Figure 583, PA6 gear rim (M = 6, AL), damaged part. The gear rim is working together with the gear wheel in Fig. 582. The gear rim edges are poorly molded (blue arrows) and have cold-flow areas (arrows 1 and 2), and the gear ring teeth have a distinct orange skin. That means the processing was too cold (see also Figs. 582 and 584, → impression, poor, → cold-flow areas, → orange skin, and → processing, too cold).

Figure 584 ••Assembly of components makes sense, ••Gear wheel and gear rim with dividing error

Figures & Text

Dividing error

Figure 584, PA6 gear wheel and gear rim (M = 8, AL), damaged parts from Figs. 582 and 583. In addition to the microscopic examination of the disassembled supplied samples (gear wheel and gear rim) these were assembled to study the interaction. Here, a dividing error was discovered with the missing bearing, so the gear was difficult to push all the way into the gear ring and thereby caused increased operating noises. With a quality or damage examination, it is always advisable to install items that belong together. This results in a more comprehensive understanding and often leads to many more answers. In summary, the causes of damage were: deformed gear wheel edges, poorly molded gear wheel edges with cold-flow areas, gear ring teeth with a pronounced orange skin, and a dividing error that mainly caused the high running noise and stiffness.

437


LM Subchapter: Mold

Figure 585 ••Comparative examination, ••Impression of ABS, poor, ••Mold filling, poor

Poor injection

Figure 585, ABS cover with bridges (M = 6, AL). When comparing the bridges, a poor injection (mold impression or filling) on the right bridge can be seen. Cause was an unequal temperature control of the mold. That means the mold was too cold in this area. And due to the molding compound temperature that was too cold there, the holding pressure could not act effectively enough and press more molding compound through for shrinkage compensation (see also → holding pressure and → mold filling).

Figure 586

Figures & Text

••Comparative examination of the impression of PC, ••Improve surface

Figure 586, PC telephone housing (M = 18, AL) with a poor impression of the surface graining that the customer complained about. The processing parameters had the usual injection molding values. The holding pressure was 80% of the injection pressure and the holding pressure time was 0.3 s. To improve the impression, tests were run (see also Fig. 587).

438


LM Subchapter: Mold

Figure 587 ••Comparative examination of the impression of PC, ••Impression, good, through initially high holding pressure ••Lower holding pressure to end

Figure 587, PC telephone housing (M = 30, AL). To improve the poor impression of the surface graining in Fig. 586, a series of tests were run with varying processing parameters: pressures, temperatures, and times. The best result was obtained with an initially high holding pressure with 95% of the injection pressure that was lowered before the end of the holding pressure time at 0.2 s. This improved the mold impression and simultaneously reduced the risk of high molded part stresses, which are especially frozen at a high holding pressure, at the end of the holding pressure time.

Figure 588

Figures & Text

••Cooling in PE, extreme, ••Ejector pin causes cooling, ••Damage after mold installation, ••Operating temperature is not reached, ••Ejector marking

Figure 588, PE sleeve (M = 18, DL). The sleeve in the figure center shows an extreme cooling in the molded part with deep marks from the ejector pin. In this area, the molded part material cooled too quickly, without apparent spherulite formation. The damage occurred after the mold installation at the beginning, simply because the ejector pin did not reach the correct operating temperature (steady temperature).

439

Appendix Tables of the Plastics Used in this Handbook (with Abbreviations) and Literature References

441

Appendix

Appendix

Table 1: Plastics Used in the Glossary with Abbreviations

Abbreviation

Plastic name

ABS

Acrylonitrile butadiene styrene copolymer

ABS/PC

Polymer blend, acrylonitrile butadiene styrene/polycarbonate

ABS-GF20

Acrylonitrile butadiene styrene with 20% glass fibers

AMMA

Acrylonitrile-methyl methacrylate

ASA

Nitrile styrene acrylate copolymer

C-PVC

Polyvinyl chloride post-chlorinated

CA

Cellulose acetate

CAB

Cellulose acetobutyrate

CP

Cellulose propionate

ECB

Ethylene bitumen copolymer

EP

Epoxy resin

EPDM

Ethylene propylene tar copolymer

ETFE

Ethylene tetrafluoroethylene (injection moldable)

FEP

Fluorinated ethylene propylene (injection moldable)

Fluoroelastomer

Fluoroelastomer with magnesium oxide particles

GF-UP

Unsaturated polyester resin reinforced with glass fibers

HDPE

High density polyethylene

LDPE

Low density polyethylene

MS

Modified silane (joint sealer)

PA

Polyamide

PA50

Polyamide 50

PA/PE

Polyamide conditioned with PE

PA/PTFE

Polyamide with added PTFE particles

PA4.11

Polyamide 4.11

PA4.6

Polyamide 4.6

PA6

Polyamide 6

PA6.3

Polyamide 6.3, transparent

PA6.6

Polyamide 6.6

PA6.6-GF25

Polyamide 6.6 with 25% glass fibers

PA6.6-GF30

Polyamide 6.6 with 30% glass fibers

PA6-GF15

Polyamide 6 with 15% glass fibers

PA6-GF20


PA6-GF30


PA6-GF30/PE

Polyamide 6 with 30% glass fibers and polyethylene

PA-GF20

Polyamide with 20% glass fibers

PA-GF25


PA-GF35


PB

Polybutene

PBT

Polybutene terephthalate

PBT T40

Polybutene terephthalate with 40% talc

PBT/PC

Polybutene terephthalate polycarbonate polymer blend

PBTB

Polybutene terephthalate

442

Appendix

Abbreviation

Plastic name

PBTP-GF20

Polybutene terephthalate with 20% glass fibers

PC

Polycarbonate

PC-CF10

Polycarbonate with 10% carbon fibers

PC-GF25

Polycarbonate with 25% glass fibers

PC-GF30


PC-GF35


PCTFE

Polychlorotrifluoroethylene PE, glass fibers, and PE layers

PE/PA6/PP/PE

Composite film with PE, PA6, PP, and PE layers

PE/PETP/PA

Composite film with PE, PETP, and PA layers

PE63

Polyethylene 63 (PE with 6.3 N/mm2 loadable, 50 years at 20 °C)

PE80

Polyethylene 80 (PE with 8.0 N/mm2 loadable, 50 years at 20 °C)

PE100

Polyethylene 100 (PE with 10 N/mm2 loadable, 50 years at 20 °C)

PEEK

Polyether ether ketone

PE-RT/AL/PE-RT

PE, aluminum, and PE layers

PETP

Polyethylene terephthalate

PE-X

Polyethylene, electron beam crosslinked

PE-Xc

Polyethylene, chemically crosslinked

PFA

Perfluoroalkoxy alkane or perfluoroalkoxy copolymer

PF-GF-Cu

Polyformaldehyde resin with glass fibers and copper fibers

PIB

Polyisobutylene

PLA98

Medical plastic for bone fixing

PMMA

Polymethyl methacrylate

PMMA/ABS/PC

Layer plate with PMMA, ABS, and PC layers

PMMA/PVC-U

PVC-U window profile with PMMA/PVC laminating film

Polysulfide 2C

Polysulfide joint sealer 2C (two-component compound)

POM

Polyoxymethylene

POM-GF30

Polyoxymethylene with 30% glass fibers

PP

Polypropylene

PP-T40

Polypropylene with 40% talc

PP/PE

Polypropylene polymer blend

PP100

Polypropylene 100

PPE

Polyphenylene oxide

PP-GF30

Polypropylene with 30% glass fibers

PP-GF40

Polypropylene with 40% glass fibers

PPO

Polyphenylene oxide

PPO-GF35

Polyphenylene oxide with 35% glass fibers

PP-R

Polypropylene random copolymer

PP-R/AL/PP-R

Polypropylene random copolymer with aluminum layer

PPS

Polyphenylene sulfide

PPS-GFM

Polyphenylene sulfide, mineral and glass fiber reinforced

PPSU

Polyphenylene sulfone (polyimide)

PP UV-stabilized

Polypropylene UV-stabilized

Appendix

PE/glass fiber/PE layers

443

Appendix

Abbreviation

Plastic name

PS

Polystyrene

PTFE

Polytetrafluoroethylene

PUR

Polyurethane

PUR 1C

Polyurethane foam 1C (one-component foam)

PUR integral foam

Polyurethane-integral foam

PUR foam

Polyurethane foam

PUR adhesive

Polyurethane adhesive

PVC

Polyvinyl chloride

PVC/EPDM

Polyvinyl chloride pipe with EPDM inliner

PVC-GF15

Polyvinyl chloride with 15% glass fibers

PVC-U

Polyvinyl chloride without plasticizer

PVC-U/PMMA

PVC-U profile with PMMA film laminated

PVDF

Polyvinylidene fluoride

SAN

Styrene acrylonitrile copolymer

SB

Styrene butadiene copolymer

SBR

Styrene butadiene rubber

SI (SIR)

Silicone rubber

TEEE

Thermoplastic elastomer with sulfide-ether basis

TPE

Thermoplastic elastomer

UP

Unsaturated polyester resin

UP-GF

Unsaturated polyester resin, glass fiber reinforced

VA

Vinyl alcohol

Vicryl

Medical plastic for wound stitches

VPE

Polyethylene, crosslinked

VPE/VA

Crosslinked polyethylene pipe with vinyl acetate jacket

WPC

Wood plastic composites (“plastic wood”)

Appendix

Table 2: Literature

Author/Company

Title

R. Jung GmbH

“Mikrotom-Messer und Zubehör,” R. Jung GmbH, Heidelberger Str. 17–19, 69226 Nußloch (now Leica), Germany

R. Jung GmbH

“Mikrotom-Nachrichten,” no. 1/2, short version, R. Jung GmbH, February, 1958

BASF

N. N.: “Kunststoff-Verarbeitung im Gespräch,” Extrusion, 4th ed., revised edition

BASF

N. N.: “Kunststoff-Werkstoffe im Gespräch: Aufbau und Eigenschaften”

BASF

N. N.: “Kunststoff-Physik im Gespräch,” 3rd ed., unrevised

Bayer AG

“Verarbeitungsparameter für Spritzgießer,” Bayer AG

Friel, P.

“Die Werkzeugtemperatur: Eine Herausforderung an Temperiersysteme,” SKZ Seminar: Economic production with optimum mold temperature during injection molding, Würzburg, Germany, 1995

Fröschle, E.

“Temperiergeräte,” SKZ Seminar: Economic production with optimum mold temperature during injection molding, Würzburg, Germany, 1995

Gastrow, H.

“Der Spritzgießwerkzeugbau,” Carl Hanser Verlag, Munich

444

Appendix

Title

Gries, H.

“Temperiermedien und deren Behandlung,” SKZ Seminar: Economic production with optimum mold temperature during injection molding, Würzburg, Germany, 1995

Heuel, O.

“Werkzeugtemperierung mit Flüssigen Medien unter Verwendung Normalisierter Bauteile,” information brochure, Hasco Standards

Kapitza, H. G.

“Mikroskopieren von Anfang an,” Zeiss

Knappe, W.

“Die Festigkeit von Kunststoffen in Abhängigkeit von Verarbeitungs bedingungen,” Kunststoffe, 51, 1961

Kurr, Friedrich

“Die Schweißverfahren für Thermoplastische Kunststoffe,” Symposium: Plastic welding technology, Chamber of Congress Hall, Munich Theresienhöhe, conference handbook, 1973

Kurr, Friedrich

“Probenvorbereitung, Dünnschnitt- und Dünnschliffverfahren für Durchlicht und Auflichtmikroskopie,” SKZ Conference: Microscopic studies on plastics, conference handbook, Würzburg, Germany, 1985

Kurr, Friedrich

“Mikroskopische Schadensaufklärung an Kunststoff-Formteilen und Halbzeug,” SKZ Seminar: Light microscopy of plastics, seminar manual, Würzburg, Germany, 1991

Kurr, Friedrich

“Dünn- und Anschlifftechnik für Spröde, Gefüllte bzw. Verstärkte Werkstoffe,” Seminar: Light microscopy of plastic, Department for Plastics Technology, University of Erlangen, Germany, seminar manual, 1992

Kurr, Friedrich

“Beispiele Mikroskopischer Schadensaufklärung (anhand von Farbdias),” Seminar: Practical failure analysis and quality assurance of plastics, Technical Academy branch, Sarnen, Switzerland, seminar manual, 1992

Kurr, Friedrich

“Mikroskopische Schadensaufklärung an Kunststoff-Formteilen und Halbzeug,” Seminar: Preparation techniques and light microscopy of polymer materials, Department for Plastics Technology, University of Erlangen, Germany, conference handbook, 1993

Kurr, Friedrich

“Beispiele lichtmikroskopischer Schadensaufklärung,” SKZ Conference: Two Würzburg days of instrumental analysis of polymer technology, conference handbook, Würzburg, Germany, 1995

Kurr, Friedrich

“Lichtmikroskopie, Probenpräparation, Qualitäts- und Schadens sicherung,” SKZ Seminar: Failure analysis and quality assurance of molding compounds and semifinished parts and molded parts, seminar manual, Würzburg, Germany, 1996

Kurr, Friedrich

“Mikroskopie zur Untersuchung von Kunststoffen,” SKZ Seminar: Failure analysis and quality assurance of molding compounds and semifinished parts and molded parts, Würzburg, Germany, 1997

Patzelt, Walter

“Polarisationsmikroskopie: Grundlagen, Instrumente, Anwendungen,” Leitz

RWTH Aachen

“Spritzgießen-Verfahrensablauf, Verfahrensparameter, Prozessführung,” Institute of Plastics Processing at RWTH Aachen, Aachen, Germany

Struers GmbH

“Struers Metalog,” Chapters 4 and 5, Struers GmbH, Albert‑Einstein‑Str. 5, 40699 Erkrath, Germany

Thienel, P.

“Formfüllvorgang beim Spritzgießen von Thermoplasten,” dissertation at RWTH Aachen, Aachen, Germany, 1977

445

Appendix

Author/Company

Appendix

Author/Company

Title

VDI Guidelines

Damage of thermoplastic products made of plastics through: Construction (VDI 3822 sheet 2.1.1) Processing (VDI 3822 sheet 2.1.2) Material choice and material (VDI 3822 sheet 2.1.3) Mechanical load (VDI 3822 sheet 2.1.4) Thermal load (VDI 3822 sheet 2.1.5) Tribological load (VDI 3822 sheet 2.1.6) Medial load (VDI 3822 sheet 2.1.7) Weathering load (VDI 3822 sheet 2.1.8) Microbial load (VDI 3822 sheet 2.1.9) Analysis methods (VDI 3822 sheet 2.1.10)

VDI-Verlag

“Das Spritzgießwerkzeug,” VDI-Verlag

Walter, F.

“Das Mikrotom, Leitfaden der Präparationstechnik und des Mikrotomschneidens,” 2nd ed., revised by Schmidt, W., Ernst Leitz Wetzlar GmbH

Wübken, G.

“Einfluss der Verarbeitungsbedingungen auf die innere Struktur thermo plastischer Spritzgussteile unter besonderer Berücksichtigung der Abkühlverhältnisse,” dissertation at RWTH Aachen, Aachen, Germany, 1974

Zöllner, O.

“Der Verarbeitungsparameter Kühlung,” SKZ Seminar: Economic production with optimum mold temperature during injection molding, Würzburg, Germany, 1995

Zöllner, O.

“Die Temperierung im Spritzgießwerkzeug,” SKZ Seminar: Economic production with optimum mold temperature during injection molding, Würzburg, Germany, 1995

Appendix

Table 3: Contrast Types in Microscopy (see also Definitions Chapter)

01

AL-HF

Incident light, bright field contrast

02

DL-HF

Transmitted light, bright field contrast

03

AL-DIC

Incident light, differential interference contrast

04

DL-DIC

Transmitted light, differential interference contrast

05

AL-DIC + 

Incident light, differential interference contrast

06

DL-DIC + 

Transmitted light, differential interference contrast

07

AL-DF

Incident light, dark field contrast

08

DL-DF

Transmitted light, dark field contrast

09

AL-FL

Incident light, fluorescence contrast

10

DL-FL

Transmitted light, fluorescence contrast

11

AL-PH

Incident light, phase contrast

12

DL-PH

Transmitted light, phase contrast

13

AL-POL

Incident light, polarization contrast

14

DL-POL

Transmitted light polarization contrast

15

AL-POL + 

Incident light, polarization contrast

16

DL-POL + 

Transmitted light, polarization contrast

Contact information and offerings of the South German Plastics Center can be found at www.skz.de/en/

446

[F. Kurr] Handbook of Plastics Failure Analysis(BookZZ.org)

Recommend Documents