Polymeric materials
Materials composed of long-chain molecules (polymers) with repeating structural units. Polymers can be natural (rubber, cellulose) or synthetic (plastics like polyethene, PVC). Their mechanical properties depend on temperature and strain rate.
Real World
Natural rubber in car tyres stretches enormously under deformation (high strain, low Young's modulus ~0.01 GPa) yet springs back elastically, demonstrating the unique viscoelastic behaviour of polymer chains.
Exam Focus
If asked to sketch a polymer stress-strain graph, draw a curved (non-linear) elastic region — not a straight line — to gain the distinguishing mark.
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