1. Elastomers: The polymer chains are held together by weak intermolecular forces.
Example – Buna – S, Buna – N, Neoprene.
2. Fibres: They have strong forces of attraction.
Example – Polymides, (Nylon 6,6), polyesters.
3. Thermoplastics: They are long chain molecules capable of repeatedly softening on heating and hardening on cooling.
Example – Polythene, polystyrene.
4. Thermosetting plastics: They do not become soft on heating and cannot be remoulded.
Example – Bakelite, Nylon – 6,6, belong to fibres.
