Mention the types of polymers formed on the basis of intermolecular forces. Write any two uses of low density polyethylene.

Answer: Elastomers, fibres, thermoplastics and thermosetting polymers; LDPE is used for carry bags, films, squeeze bottles, etc.

Classification on the basis of intermolecular forces:

1. Elastomers: weakest forces; rubber-like, stretch and regain shape, e.g. vulcanised rubber, neoprene.
2. Fibres: strongest forces (hydrogen bonding), high tensile strength, thread-forming, e.g. nylon 6,6, terylene.
3. Thermoplastics: intermediate forces; soften on heating and harden on cooling repeatedly, e.g. polythene, PVC, polystyrene.
4. Thermosetting polymers: extensively cross-linked; set permanently on heating and cannot be remoulded, e.g. bakelite, melamine-formaldehyde.

Uses of LDPE (any two): making carry bags and packaging films, squeeze bottles, toys, insulation of electric wires and cables, and flexible pipes.