question_answer 17)

Define thermoplastics and thermosetting polymers withtwo examples of each. Effect of heat on these polymers is the basis of this classification.  

Answer:

Thermoplastic polymers Those polymers (linear or slightlybranched long chain molecules), which are capable of softening onheating and hardening on cooling are called thermoplastics. These polymers possess intermolecular forces of attraction intermediatebetween elastomers and fibres. Examples are polythene, polyvinylchloride, polystyrene etc. Thermosetting polymers Those polymers (cross-linked or heavilybranched molecules), which on heating do not soften and cannot beremoulded are called thermosetting polymers. On heating they undergoextensive cross-linking in moulds and becomes infusible. Examples arebakelite, urea- formaldehyde resins etc.