Two nearly equivalent approaches for describing the non-linear creep behavior of glassy polymers

Abstract

Two approaches are proposed to account for the creep curve of glassy polymers under high applied stress; one is analytical, the other is in the form of a ladder mechanical model. Both approaches consider that creep deformation induces the rejuvenation of the sample, giving rise to faster kinetics, and they predict an inflection in the creep curve. The related responses were found to fit experimental data better than the stretched exponential law, especially at high strain. The mechanical model must be preferred because it is hierarchical, which is useful for visualization and allows memory effects to be taken into account.