CHEMBIO 3BM3 Lecture Notes - Lecture 12: Ductility, Work Hardening, Viscoelasticity
21 Apr 2019
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Brittle vs ductile: brittle = glass-like behaviour, temp below tg, shatters, above tg, leathery-like. More flexible: may be able to break it eventually but it will resist breaking apart. Area under stress/strain curve = energy it takes to break a material. Ductility: extent to sustaining plastic deformation without rupture, elongation and reduction of area are common indices of ductility. Toughness: resistance of a material to fracture or break, measured in units of energy, different to strength. Stiffness: measure of resistance of plastics to bending, includes both plastic and elastic behaviour, apparent value of elastic modulus. As you pull an object more and more, you introduce a greater violation to an object being truly unidirectionally deformed. Most materials: elastic up to 1-2% strength (bounce back) As you stretch further, it adopts viscoelastic properties: dampening behaviour, force is applied but response is delayed. Plateau: keeps trying to reorganize crystals because it wants it there.
