Lab #1: Polymers Testing: How to identify different plastics 1.
Introduction
Material Testing is important in identifying the materials types and identifying the properties of those material. Mechanical tests such as tensile testing and hardn ess testing are excellent ways to provide mechanical properties of the material. But it is important important to determine the reaction of materials to specific changes such as chemicals, flames, high heat, etc. Those reactions will depend on the plastics structure. Plastics are different based on their differences in their characteristics. There are different plastics types, such as, polyolefin (HDPE, (HDPE, LDPE, PP), aromatic plastics (PS, benzene, toluene), elastomers (e.g. silicone), and thermosets (e.g. (e.g. epoxy, phenolic). Knowing characteristics of plastics will allow you to correctly design parts made with plastic.
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Objectives: The purpose of this experiment is to:
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Explain the different characteristics of different types of plastics. Such as, PVC, silicone, polystyrene, HDPE (high density polyethylene), and PP.
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Introduce you to different types of materials with their recycling code ID.
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Identify different types of plastics using The Plastics and Elastomers ID Chart.
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Procedure:
You will be divided into 4 groups of 4 students each. We will use five different types of materials (PVC, Silicone, PS, HDPE, and PP). We will use five different types of tests. Those tests are Visual Appearance, buoyancy, solvency (Reaction to Acetone &other solvents), Flame test (includes observations about smoke, flame color, speed of burning, and whether it is selfself extinguishing), and heat gun (basically a test if the material melts). The Plastics and Elastomers Identification Chart (attached) Procedure will be used in this test: 1. The material should be classified if it is Thermoplastics, Thermosets, The rmosets, or Elastomers using the visual test and the Heat gun test te st depending on the Plastics and Elastomers Identification Chart attached. 2. Then Buoyancy Test will be used to test if the material floats or sinks. 3. Once the material is known if it floats or sinks, the flame test will be p erformed to specify exactly the type of the material mate rial that we are using. The details of all the tests are a s follow:
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Step 1: Visual Appearance Translucency, transparency, and opaqueness are important distinguishing characteristics of a plastic. For the purpose of this lab, we will include the qualitative tactile characteristics of the plastic (i.e. what it feels like, e.g. hard, soft, rubbery, etc.).
Step 2: Heat Gun Effect This test will help us determine if the plastic is a thermoset or a thermoplastic. It will also help us determine how much heat the plastic will absorb before it distorts and may reach a melting temperature. The melting temperature can convey some important information about a plastic. Step 3: Buoyancy Test Buoyancy Test is used to check if the material sinks or floats. The five types of materials will be put in a beaker filled with water. A comparison between the five materials can be performed.
Step 4: Flammability We will use a lighter to ignite a small sample of each plastic. Refer to the Plastics Identification Chart for flammability characteristics shown below. Smoke, dripping, odor, self-extinguishing, and other observations will help you refine your identification of an unknown plastic.
Step 5: Chemical Solubility: for the chemical solubility, the chart available in the Lab. will b e used to specify if the material is affected by specific c hemicals or not. Acetone will be used in this test. Polymers, like all materials, may be affected by exposure to various chemicals. The most common effects are various degrees of dissolution. During exposure, the polymer may swell, soften, or dissolve. These reactions can be used to identify either the individual polymer or at least the family of polymers the individual represents. We will use acetone and expose the various plastics to it. Plastics exposed to solvents for long periods of time will show the full extent to which a plastic is affected. There are many solvents that can affect plastics, from water to strong acids.
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Use the space below to record your observations. Material Visual Appearance (Color, Flexibility, texture, etc.) _______ _______ _______ _______ _______ Material
Heat Gun Effect (material melts, change in co lor and surface, transparency to opaqueness? etc,)
_______ _______ _______ _______ _______
Material
Buoyancy Test (sink or float)
_______ _______ _______ _______ _______
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Does it burn on its own? Must the flame be held on the specimen constantly? What is the color of the flame? What is the appearance of the smoke? Material
Flame test results
_______ _______ _______ _______ _______
Material
Reaction to Acetone & Other Solvents (swell, soften, disintegrate, melt, etc.)
_______ _______ _______ _______ _______
Material Identification using Recycling Codes: Often plastics are stamped with the material ID. The recycle chart can be used to help identify the plastic with a recycle ID. However, not all are labeled, or the labeling may be destroyed. In these cases, the polymer may be identified b y means of a few tests.
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Questions: 1. What are some typical applications for each of the following: chemically resistant plastics, gas permeable plastics, gas impermeable plastics, UV resistant plastics, and selfextinguishing plastics. Only show two applications of each with pictures.
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