Free Volume and Finite-Size Effects in a Polymer Glass under Stress

Robert A. Riggleman, Hau-Nan Lee, M. D. Ediger, and Juan J. de Pablo
Phys. Rev. Lett. 99, 215501 – Published 20 November 2007

Abstract

Molecular dynamics simulations of the nonlinear creep response of a polymer glass under tension and compression have been performed at the glass transition temperature. The dynamics were measured as the deformation proceeds using the bond autocorrelation function, and the relaxation times measured as the system is compressed or elongated exhibit a universal response. In tension, the volume increases with strain rate and the relaxation times decrease. In compression, however, the volume decreases by approximately the same amount for all of the applied stresses. Thus, decreases in free volume take place alongside a decrease of the relaxation times by over a factor of 100. We find direct evidence that a characteristic length scale exists below which the deformation of the system exhibits distinct anomalies.

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  • Received 17 July 2007

DOI:https://doi.org/10.1103/PhysRevLett.99.215501

©2007 American Physical Society

Authors & Affiliations

Robert A. Riggleman1, Hau-Nan Lee2, M. D. Ediger2, and Juan J. de Pablo1

  • 1Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, Wisconsin, 53706, USA
  • 2Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin, 53706, USA

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Issue

Vol. 99, Iss. 21 — 23 November 2007

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