Chemistry in Everyday Life — Chemistry STD 12 — Question

Thermoplastics:
Thermoplastics are linear polymers which can be repeatedly softened on heating and hardened on cooling and hence can be used again and again without any change in chemical composition and mechanical strength.

Thermosetting polymers:
Thermosetting polymers, are permanently setting polymers. On heating in a mould, they get hardened and set and cannot be softened again. This hardening on heating is due to cross linking between different polymeric chains which give rise to a three dimensional network solid. Example – Bakelite.