Nonlinear viscoelastic and viscoplastic response of glassy polymers

The main features of inelastic mechanical behavior of glassy state were stu died theoretically and experimentally in terms of tensile stress-strain and tensile creep experiments. A theoretical treatment introduced in earlier w ork, which takes into account the viscoelastic path at small strains and th e viscoplastic one at higher stresses, proved to be capable of describing t he main aspects of mechanical response of glassy polymers, i.e. nonlinear v iscoelasticity during creep procedure, and yield stress, yield strain, stra in softening and rate effect in a constant crosshead speed test.