Question

Which of the following is a thermoplastic polymer?
A. Bakelite
B. Polystyrene
C. Terylene
D. Urea formaldehyde resin
E. Nylon

Answer 1

Thermoplastic polymers have the ability to change their shape and can be moulded or folded, when it is heated up.

Complete answer:
In order to answer our question, we need to learn about the different type of polymers:
Elastomers: These are rubber-like solids with elastic properties and the polymeric chains are held together by the weakest van der Waal interactions.
The examples are buna-S, buna-N, neoprene, etc.
Fibres: These are the polymers which have quite strong intermolecular forces such as H-bonding. Due to strong intermolecular forces of attraction, fibres have high tensile strength and least elasticity, close packing of chains which impart crystalline nature. The examples are polyamides, polyesters etc.
Thermoplastic polymers: These are the polymers in which intermolecular forces of attraction are in between those of elastomers and fibres. They are neither very strong nor very weak and have no cross-links between the chains. These are the linear or slightly branched long chain polymer which is capable of softening on heating and hardening on cooling.
The examples are polythene, polystyrene, polyvinyls etc.
Thermosetting polymers: These polymers are cross-linked or heavily branched molecules, which on heating undergo extensive cross-linking between different polymer chains to give a three-dimensional network solid and again become infusable. These cannot be reused.
From the options given in the question, we can say that the thermoplastic polymer is polystyrene. The structure is given below:

So, we get the correct answer for the question as option B.

Note:
It is to be noted that the shapes of thermoplastic polymers can easily be changed upon application of temperature, which is not the case of thermosetting polymers. Thermoplastic polymers can be made to regain their shape.