Cue Column | Note Column

By source type? | Natural: cellulose (plants), starch, natural rubber (Hevea), proteins, nucleic acids. Semi-synthetic: rayon (cellulose acetate), vulcanized rubber, gun cotton (cellulose nitrate). Synthetic: polythene, nylon-6,6, Dacron, Bakelite, Teflon, PVC.

By structure type? | Linear (HDPE, nylon-6,6, Dacron): long unbranched chains — high tensile strength, high density, high crystallinity. Branched (LDPE, amylopectin, glycogen): irregular side chains — lower density, less crystalline, more flexible. Cross-linked/Network (Bakelite, melamine-HCHO, vulcanized rubber): 3D covalent network — hard, infusible, rigid.

By polymerization? | Addition: unsaturated monomer (C=C), chain-growth, no byproduct, same empirical formula as monomer. Condensation: bifunctional monomers, step-growth, loses small molecule (H2O usually), different formula from monomer.

Thermoplastic vs thermosetting? | Thermoplastic: intermolecular forces only (van der Waals, H-bonds) → softens + remolded on heating. Examples: polythene, PVC, nylon, Dacron. Thermosetting: covalent cross-links → chars/burns on heating, cannot be remolded. Examples: Bakelite, melamine-formaldehyde, urea-formaldehyde.

Summary: Polymer classification has 4 independent axes — always classify on ALL four (source, structure, polymerization type, thermal behavior). NEET questions often test two axes simultaneously.