Molecular Chain Plasticity Model Like Crystal Plasticity Theory Using Probabilistic Response Law of Inelasticity Based on Change of Local Free Volume for Glassy Polymer

Abstract

Polymers have desirable mechanical properties and have been widely used as structural materials instead of metals under severe mechanical conditions. The molecular chain network model based on J2-flow theory and Argon's hardening law cannot directly express a deformation-induced orientation of molecular chains, a propagation of high strain rate shear band and a nonlinear viscoelastic response before the initial yielding that is an inelastic behavior peculiar to polymer. In this paper, a new concept of “molecular chain slip system” is analogically proposed on the basis of crystal plasticity theory for metals. A molecular chain plasticity model that can reproduce the large deformation behaviors of glassy polymer mentioned above is developed by allowing an independent rotation of a slip system differently than the usual crystal plasticity framework. Moreover, the inelastic response law based on a probabilistic theory considering change of local free volume is adopted as a hardening law so as to express the nonlinear viscoelastic response.