Deviatoric Stress Driven Transient Melting Below the Glass Transition Temperature in Shocked Polymers

TL;DR

This paper reports a novel phenomenon where shock-induced deviatoric stresses cause transient melting in glassy polymers, revealing rapid stress-driven transitions akin to melting followed by slower relaxation.

Contribution

It introduces the concept of stress-driven transient melting in polymers under shock, linking deviatoric stress to rapid backbone transitions and melt-like behavior.

Findings

Deviatoric stresses induce rapid backbone dihedral angle transitions.

Transient melting occurs below the glass transition temperature.

Stress relaxation resembles that of polymer melts.

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 negate a significant fraction of these processes resulting in the dynamical glass transition in rubbers. In this letter we report the inverse, a transient melting of 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 the slower relaxation expected for glasses.