Concept:Thermoplastic polymers are linear or moderately branched polymers held together by intermolecular forces that soften reversibly upon heating and harden upon cooling.
Formula / Reaction:$$-[\text{CH}_2-\text{CH}(\text{Cl})]_n- \xrightarrow{\Delta} \text{Softens (Remoldable)} \xrightarrow{\text{Cool}} \text{Hardens}$$
Solution:- Polyvinyl chloride (PVC) possesses linear chains with dipole-dipole attractions that can be repeatedly softened by thermal energy and reshaped.
- Official UHS MDCAT Key Alignment: Although PVC is structurally a homopolymer, the official exam key designates Thermoplastic polymer as the correct classification based on thermal behavior.
Why other options are incorrect:- Thermosetting polymer: Thermosets form irreversible cross-linked covalent networks that degrade rather than melt upon heating.
- Copolymer: Formed from two or more distinct monomer types, whereas PVC is derived entirely from vinyl chloride.
- Homopolymer: Structurally true, but secondary to Option C in the official competitive scoring key.
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