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FURTHER QUESTIONS and ANSWERS ON POLYMERS

V. Ryan 2010

 

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1. What does the term thermoset polymer mean?

 
A thermoset polymer sets due to heat being applied. Most thermoset plastics cannot be reshaped again, even if further heat is applied.
 
2. Name a thermosetting plastic and a product manufactured from this material.
 
Urea Formaldehyde is an excellent example of a thermosetting plastic. It is used in electrical fittings.
 
3. With reference to your chosen material’s physical properties, explain why it is used in the product named.
 
Urea Formaldehyde is an excellent insulator as it does not conduct electricity. It can be used in manufacturing processes such as injection and compression moulding. Furthermore, it is fire resistant and a tough / hard material, making it ideally suited for the manufacture of electrical fittings.
 
 
 
4. Describe some of the disadvantages of using the thermosetting plastic you have named.
 
Urea formaldehyde is difficult to recycle because it cannot reformed/shaped through further heating. Thermosetting plastics have a limited colour range, unlike many other plastics. Also, when used in the injection moulding process, thermosetting plastics such as urea formaldehyde, are slow to cure. This can slow down the manufacturing of products manufactured from this type of plastic.
 
5. Complete the diagram of an injection moulding machine drawn below.
 
 
 
 
6. Describe how an injection moulding machine works, during the manufacture of the electric socket face plate.
 
The diagram (question 5) shows a typical injection moulding machine. It is being used to manufacture the face plate to an electrical socket. The material being used is the thermosetting plastic called urea formaldehyde. The urea formaldehyde granules / powder is placed into the hopper. It drops down on to a rotating thread and travels along its distance. During this process the granules / powder is heated and becomes fluid. It is then injected into a mould of the socket. Once cool it can be taken out and excess ‘plastic’ is trimmed away. Waste is kept to a minimum as urea formaldehyde is very difficult to recycle.
 
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