A microscopic view of accelerated dynamics in deformed polymer glasses

TL;DR

This study uses molecular dynamics simulations to analyze how deformation accelerates relaxation dynamics in aging polymer glasses, revealing a universal strain-dependent acceleration factor and narrowing of relaxation time distributions.

Contribution

It provides a microscopic understanding of accelerated dynamics in deformed polymer glasses and introduces a universal strain-dependent acceleration factor.

Findings

Dynamics are accelerated by several orders of magnitude.

Relaxation time distribution narrows during creep.

Acceleration factor depends universally on global strain.

Abstract

A molecular level analysis of segmental trajectories obtained from molecular dynamics simulations is used to obtain the full relaxation time spectrum in aging polymer glasses subject to three different deformation protocols. As in experiments, dynamics can be accelerated by several orders of magnitude, and a narrowing of the distribution of relaxation times during creep is directly observed. Additionally, the acceleration factor describing the transformation of the relaxation time distributions is computed and found to obey a universal dependence on the global strain, independent of age and deformation protocol.