Effect of yielding on the viscoelastic response of amorphous glassy polymers

Constitutive equations are derived for the nonlinear viscoelastic behavior of amorphous glassy polymers. The model is based on the theory of cooperative relaxation in a version of the trapping concept. Stress–strain relations are applied to fit experimental data for polycarbonate in the sub‐yield and post‐yield regions. Fair agreement is demonstrated between observations and results of numerical simulation. It is revealed that yielding causes substantial changes in the energy landscape of amorphous polymers. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2383–2393, 2001