a) Natural polymer – proteins, cellulose, starch, resins, natural rubber.
Synthetic polymer- Polythene, Nylon 6,6, BunaS, Teflon, PVC.
b) Thermoplastic polymers – These are linear or slightly branched long-chain molecules capable of repeatedly softening on heating and hardening on cooling. These polymers possess intermolecular forces of attraction intermediate between elastomers and fibres. These can be reused.
Example – polythene, polystyrene, polyvinyl.
Thermosetting polymers – These polymers are cross linked or heavily branched molecules, which on heating undergo extensive cross-linking in moulds and again become infusible. These cannot be reused.
Example – bakelite, urea-formaldehyde resins.