Volume 79, Number 2, July 2007
Article Number 26006
Number of page(s) 6
Section Condensed Matter: Structural, Mechanical and Thermal Properties
Published online 12 July 2007
EPL, 79 (2007) 26006
DOI: 10.1209/0295-5075/79/26006

Stress-enhanced mobility and dynamic yielding in polymer glasses

Kang Chen and Kenneth S. Schweizer

Department of Materials Science, University of Illinois - Urbana, IL 61801, USA

received 31 March 2007; accepted in final form 8 June 2007; published July 2007
published online 12 July 2007

A statistical mechanical theory is proposed for stress-induced acceleration of thermally driven barrier hopping and segmental relaxation, dynamic yielding and devitrification in polymer glasses. The approach is built on the concept of a nonequilibrium free energy determined by the amplitude of temperature-dependent collective density fluctuations, and the idea that stress induces an instantaneous force on a segment. Multiple predictions that fundamentally differ from the phenomenological Eyring model are made for the temperature and strain rate dependence of the dynamic yield stress and deformation modified segmental relaxation time, which are in accord with experiments and simulations.

61.25.Hq - Macromolecular and polymer solutions; polymer melts; swelling.
64.70.Pf - Glass transitions.
62.20.Fe - Deformation and plasticity (including yield, ductility, and superplasticity).

© Europhysics Letters Association 2007