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STUDY THE EFFECT OF ACIDS AND BASES ON THE TENSILE STRENGTH OF A FIBRE. A Project Report Submitted by
HYDER QAID JOHAR In partial fulfillment of the
CBSE GRADE XI - B IN Chemistry AT
INDIAN PUBLIC SCHOOL ROLL NO:-11214 2016-17
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BONAFIDE CERTIFICATE This is to certify that HAIDER KHOKHAWALA of Grade XI-B, INDIAN PUBLIC SHOOL with Roll Number 14 has compiled this Chemistry project in partial fulfillment of the requirements as prescribed by CBSE in the year 2016-17.
Signature of the Teacher In-charge
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ACKNOWLEDGEMENT I warmly acknowledge the continuous encouragement and timely suggestions offered by our dear Principal Mr.K.A.Rodrigues. I extend my hearty thanks for giving me the opportunity to make use of the facilities available in the campus to carry out the project successfully. I am highly indebted to Mrs. Rachel Thomson & my lab teacher Mrs. Julie sam for the constant supervision, providing necessary information and supporting in completing the project. I would like to express my gratitude towards them for their kind co-operation and encouragement. Finally I extend my gratefulness to one and all who are directly or indirectly involved in the successful completion of this project work.
Signature of the Candidate
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INDEX S.NO NAME 1.
REMAR K
Pg No. 2
2.
BONAFIDE CARTIFICATE. ACKNOWLEDGMENT.
3.
INTRODUCTION.
5-6
4.
THEORY
7-8
5.
AIM
9
6.
APPARATUS REQUIRED
10
7.
PROCEDURE.
11
8.
OBSERVATIONS
12
9.
CONCLUSION.
13
10.
PRECAUTIONS
14
11.
BIBLIOGRAPHY
15
3
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INTRODUCTION Fibre is a class of materials that are continuous filaments or are in discrete elongated pieces, similar to lengths of thread. A fiber is an elongated tapering thick-walled plant cell that imparts elasticity, flexibility, and tensile strength. Tensile strength of fibres can be determined by hanging weights tied to it and comparing the weight a string can hold. Traditionally, natural fibers have been used in all cultures for making utilitarian products. Different parts of the plant are used. Fibers can be extracted from the bark (banana, jute, hemp, and ramie), stem (banana, palm, and bamboo), leaf (palm, screw pine, sisal, agave), husk (coir), seeds (cotton), and grass (sikki, madhurkati, benakati, munj). Animal fibers are obtained from a variety of animal coats, and insect fibers from cocoons. Even before the arrival of man-made fibers, manufacturers could create hundreds of different kinds of fabrics, differing mainly by fiber content, weight, style of weave, or sheen. Here are just a few of these historic fabrics, along with the natural
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fiber from which they were originally made (nearly all can be made now with other fibers, either natural or synthetic).They are very important in the biology of both plants and animals, for holding tissues together. Human uses for fibers are diverse. They can be spun into filaments, string, or rope, used as a component of composite materials, or matted into sheets to make products such as paper or felt. Fibers are often used in the manufacture of other materials. The strongest engineering materials are generally made as fibers, for example carbon fiber and Ultra-high-molecularweight polyethylene. The history of man-made fibers is less than a century old; until 1910, there were no synthetic or chemical fibers. Today, by mixing different components, manufacturers can take the basic fibers listed below and make them more waterproof or more absorbent, warmer or cooler, thicker or thinner, stiffer or more supple. Some, like polyester and spandex, combine well with natural fibers, making fabrics that wrinkle less or are more form-fitting. Synthetic fibers can often be produced very cheaply and in large amounts compared to natural fibers, but for clothing natural fibres can give some
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benefits ,such as comfort ,over their synthetic counterparts.
THEORY Depending upon the source, various fibres can be categorized as: 1. Animal fibre(e.g., silk and wool) 2. Vegetable fibre(e.g., cotton and linen) 3. Synthetic fibre(e.g., nylon and rayon) Natural fibres can be classified according to their origin. The vegetable, or cellulose-base, class includes such important fibres as cotton, flax, and jute; the animal, or protein-base, fibres include wool,mohair, and silk; an important fibre in the mineral class is asbestos. The vegetable fibres can be divided into smaller groups, based on their origin within the plant. Cotton, kapok, and coir are examples of fibres originating as hairs borne on the seeds or inner walls of the fruit, where each fibre consists of a single, long, narrow cell. Flax, hemp, jute, and ramie are bast fibres, occurring in the inner bast tissue of certain plant stems and made up of overlapping cells. Abaca, henequen, and sisal are fibres occurring as part of the fibro vascular system of the leaves. Chemically, all vegetable fibres consist mainly of cellulose,
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although they also contain varying amounts of such substances as hemicellulose, lignin, pectins, and waxes that must be removed or reduced by processing. The animal fibres consist exclusively of proteins and, with the exception of silk, constitute the furor hair that serves as the protective epidermal covering of animals. Silk filaments are extruded by the larvae of moths and are used to spin their cocoons. With the exception of mineral fibres, all natural fibres have an affinity for water in both liquid and vapour form. This strong affinity produces swelling of the fibres connected with the uptake of water, which facilitates dyeing in watery solutions. Unlike most synthetic fibres, all natural fibres are nonthermoplastic—that is, they do not soften when heat is applied. At temperatures below the point at which they will decompose, they show little sensitivity to dry heat, and there is no shrinkage or high extensibility upon heating, nor do they [15 become brittle if cooled to below freezing. Natural fibres tend to yellow upon exposure to sunlight and moisture, and extended exposure results in loss of strength. All natural fibres are particularly susceptible to microbial decomposition, including mildew and rot. Cellulosic fibres are decomposed by aerobic bacteria (those that live only in oxygen) and fungi. Cellulose mildews and decomposes rapidly at high humidity and high temperatures, especially in the absence of light. Wool and silk are also subject to microbial decomposition by bacteria and molds. Animal fibres are also subject to damage by moths and carpet beetles; termites and silverfish attack cellulose fibres. Protection against both microbial damage and
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insect attacks can be obtained by chemical modification of the fibre substrate; modern developments allow treatment of natural fibres to make them essentially immune to such damage.
AIM To find the effect of acids and alkalies on tensile strength of cotton, silk and wool fibres.
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Apparatus Requirements:Cotton, wool, silk, polyester, hook, weight hanger, weights.
Chemical Requirement:Hydrochloric acid( M/10) and sodium hydroxide(M/10 ).
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Procedure:1. Cut out equal length of cotton, wool and silk threads from given samples. The threads should be nearly the same thickness. 2. Determine the tensile strength of each fibre as explained in experiment 1. 3. Soak a given thread into a dilute solution of sodium hydroxide for about 5 minutes. 4. Take it out of NaOH solution and wash it thoroughly with water and dry it in sun or oven at 40°C. 5. Determine again the tensile strength of woolen thread as explained in experiment 1 6. Now take another piece of wool thread and soak it in hydrochloric acid for about 5 minutes. Take it out and wash thoroughly with water. Dry it and again determine its tensile strength. 7. Repeat the above procedure for the sample of cotton and nylon fibres.
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Observations:SI.N Type of O fibre.
1. 2. 3. 4.
cotton wool silk polyester
Tensile strength of fibre(N) Before after soaking after soaking Soaking. in NaOH. HCL.
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CONCLUSION. Conclusions drew from the experiment are:1. Alkalies decrease the tensile strength of woolen fibers. 2. Acids practically do not affect this fiber. 3. Tensile strength of cotton thread is decreased by acids and it remains unaffected by alkalis. 4. Nylon fiber is practically unaffected by both acids and alkalies.
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PRECAUTIONS:1. Thread must be of identical diameters. 2. Always take the same length of threads. 3. Add the weights in small amount very slowly.
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BIBLIOGRAPHY Comprehensive practical chemistry-XI Wikipedia Encyclopedia Britannica Online Encyclopedia www.textileschool.com www.meritnation.com. http://cp.literature.agilent.com/litweb/ pdf/
