Name the sub-groups into which polymers are classified on the basis of magnitude of intermolecular forces.

Explanation

The polymers are classified into the following four sub groups on the basis of magnitude of intermolecular forces present in them.
1. Elastomers : These are rubber-like solid with elastic properties. In these elastomeric polymers, the polymer chain are held together by weakest intermolecular forces.
2. Fibres : These are the thread forming solids which possess high tensile strength and high modulus. These characteristics can be attributed to the strong intermolecular forces like hydrogen bonding.
3. Thermoplastic polymers : These are linear or slightly branched long chain molecules capable of repeatedly softening on-heating and hardening on cooling. Ex-Polyethene.
4. Thermosetting polymers : These polymers are linked or heavily branched molecules, which on heating undergo extensive cross linking in moulds and again become infusible. These cannot be reused. Some common examples are bakelite, urea-formaldehyde resins,. etc.