Polymer

Macromolecules contain many connected structural units, with molecular sizes and compositions often distributed across a sample. Cellulose, natural rubber and synthetic nylon belong to this broad category. Plastics represent only part of polymer materials, alongside natural fibres and other substances with distinct structures and mechanical behaviour.

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The existence of very large molecules was once contested. Staudinger argued for covalently connected long chains, and experimental work increasingly supported this account. At DuPont, Carothers used established organic reactions to build macromolecules, connecting questions of molecular structure with the development of manufacturable new materials.

References: [1]

Chains may pack into crystalline regions or form less ordered arrangements. Branching, cross-links and intermolecular forces alter molecular movement and therefore stiffness, elasticity and thermal response. Large molecular size alone does not prescribe one combination of transparency, strength or processing temperature for every polymer.

References: [2]

Drawing can orient chains and crystalline regions along a fibre. Limited cross-linking helps elastomers recover their shape, while extensively cross-linked thermosets form rigid networks. Properties emerge from structure together with processing, so formulation, morphology and operating conditions complement the chemical name of a polymer.

References: [2]