Elastomers are polymers distinguished by their elasticity. Their molecular structure features slightly cross-linked polymer chains, enabling them to stretch and revert to their original form.
Key characteristics of elastomers are:
High flexibility and elasticity.
Resistance to deformation with rapid recovery.
Applications include rubber bands, tires, and seals.
Discussion of Alternative Choices:
(A) Thermoplastics: Polymers that reversibly change state from solid to liquid upon heating and back to solid upon cooling, lacking cross-linking.
(C) Thermosets: Polymers characterized by extensive, permanent cross-linking that hardens them irreversibly upon heating.
(D) Polyethylene: A common thermoplastic polymer, not an elastomer.
Therefore, the appropriate selection is option (B).