Deviatoric stress driven transient melting below the glass transition temperature in shocked polymers

Abstract

The relaxation of polymers around and below their glass transition temperature is governed by a range of correlated unit processes with a wide range of timescales. The fast deformation rates of shock loading can suppress a significant fraction of these processes resulting in dynamical glass transition in rubbers. In this article, we report the inverse, a transient melting of a glassy polymer under shock loading. The large deviatoric stresses near the shock front induce fast transitions in backbone dihedral angles and a stress relaxation characteristic of polymer melts. This is followed by slower relaxation expected for glasses.