Q.Arrange the following polymers in increasing order of their intermolecular forces. Nylon 6,6, Buna-S, Polythene.

Polymers are broadly classed by the strength of intermolecular forces between their chains: elastomers have the weakest forces, thermoplastics (plastics) have intermediate forces, and fibres have the strongest forces (due to close packing and hydrogen bonding).

• Buna-S is a synthetic elastomer; its polymer chains are held together by very weak van der Waals forces, allowing them to be stretched and to retract — this is the weakest of the three.
• Polythene is a thermoplastic; its chains are held by moderate intermolecular (van der Waals) forces, stronger than in an elastomer but without any strong specific interaction. …

Classify each polymer by type (elastomer / plastic / fibre) and recall the standard strength-of-forces ordering: elastomers < plastics < fibres, dr …

• Reversing the order and assuming elastomers (being flexible and 'strong' when stretched) have the strongest intermolecular forces — flexibility comes from weak forces, not strong ones. …