Plastics can be classified into two groups, Thermoplastic and [[1]] plastics.

Depending on their reaction to heat, plastics can be classified into two groups i.e. Thermoplastic and thermosetting plastics. In thermoplastic, the process of softening on heating and hardening on cooling can be repeated again and again. For example, polyethene, PVC and Teflon. However, thermosetting plastics can be softened by heating only once. For example, Bakelite.