Question

1. What is difference amongst thermoplastic, thermosets and elastomers? Include one example of each.

2. Explain how stress strain behaviour of thermoplastics, elastomers and brittle materials differ? Include stress strain curves.

3. What is a glass transition point? Explain through the curves for glass and crystalline materials.

4. How a temperature drop of 50 C below 0 C would affect polythene bottle? Explain.

5. What type of bonding explains function of adhesives?

6. Why plastic beams are not used to construct buildings and bridges? List THREE properties that make plastics unsuitable for this application.

Answer 1

1. Thermoplastics: It is polymer material which can be moldable at a certain elevated temperature and does undergo any chemical change afterwards. Polyethylene, polypropylene, PVC and more are examples of thermoplastics.

Thermoset plastic: After being heated, these plastics undergo irreversible chemical reaction. The example include epoxy resin, melamine formaldehyde etc.

Elastomer: These are physical mixture of both thermoplastic and thermoset plastics. These polymers consists of long polymer chians with having many cross linkages. Natural Rubber comes under elastomer.

Please post the other questions seperately.