Question Bank [2022] — Chemistry STD 12 Science — Question

1. Thermoplastic polymers have the property of plasticity, that is, these polymers can be easily shaped or moulded.
2. They are capable of repeated softening on heating and hardening on cooling.
3. These polymers possess moderately strong intermolecular forces that are intermediate between elastomers and fibres.
   e.g. Polythene, polystyrene, polyvinyl, etc.

Thermosetting polymers:

1. Thermosetting polymers are rigid polymers.
2. During their formation, they have the property of being shaped on heating; but they get hardened while hot. Once hardened, they cannot be softened by heating and therefore cannot be remoulded.
3. This characteristic is the result of extensive cross-linking by covalent bonds formed in the moulds during the hardening/setting process while hot.
   e.g. Bakelite, urea-formaldehyde resin, etc.