Question

What is viscoelasticity in polymers? Clearly discussed

Answer 1

Polymers show a time dependent strain. Their behaviour is neither of an elastic solid not of a viscous liquid but it lies between the two of them. Viscoelastic substances have an elastic component and a viscous component. The viscosity of a viscoelastic substance gives the substance a strain rate dependence on time. Hysteresis is observed in the stress–strain curve, with the area of the loop being equal to the energy lost during the loading cycle.When a stress is applied to a polymer, parts of the long polymer chain change positions. Polymers remain a solid material even when these parts of their chains are rearranging in order to accompany the stress, and as this occurs, it creates a back stress in the material. When the back stress is the same magnitude as the applied stress, the material no longer creeps. When the original stress is taken away, the accumulated back stresses will cause the polymer to return to its original form. The material creeps, which gives the prefix visco-, and the material fully recovers, which gives the suffix -elasticity.