Direct Measurement of Molecular Mobility in Actively Deformed Polymer Glasses
- 9 January 2009
- journal article
- other
- Published by American Association for the Advancement of Science (AAAS) in Science
- Vol. 323 (5911), 231-234
- https://doi.org/10.1126/science.1165995
Abstract
When sufficient force is applied to a glassy polymer, it begins to deform through movement of the polymer chains. We used an optical photobleaching technique to quantitatively measure changes in molecular mobility during the active deformation of a polymer glass [poly(methyl methacrylate)]. Segmental mobility increases by up to a factor of 1000 during uniaxial tensile creep. Although the Eyring model can describe the increase in mobility at low stress, it fails to describe mobility after flow onset. In this regime, mobility is strongly accelerated and the distribution of relaxation times narrows substantially, indicating a more homogeneous ensemble of local environments. At even larger stresses, in the strain-hardening regime, mobility decreases with increasing stress. Consistent with the view that stress-induced mobility allows plastic flow in polymer glasses, we observed a strong correlation between strain rate and segmental mobility during creep.Keywords
This publication has 27 references indexed in Scilit:
- Structural Rearrangements That Govern Flow in Colloidal GlassesScience, 2007
- Stress-enhanced mobility and dynamic yielding in polymer glassesEurophysics Letters, 2007
- Mechanical performance of polymer systems: The relation between structure and propertiesProgress in Polymer Science, 2005
- A thermodynamically consistent, nonlinear viscoelastic approach for modeling glassy polymersPolymer, 2004
- Spatially Heterogeneous Dynamics in Supercooled LiquidsAnnual Review of Physical Chemistry, 2000
- Three-Dimensional Direct Imaging of Structural Relaxation Near the Colloidal Glass TransitionScience, 2000
- Glass-rubber constitutive model for amorphous polymers near the glass transitionPolymer, 1995
- Large inelastic deformation of glassy polymers. part I: rate dependent constitutive modelMechanics of Materials, 1988
- Theory for the Plasticity of Glassy PolymersThe Journal of Chemical Physics, 1966
- Viscosity, Plasticity, and Diffusion as Examples of Absolute Reaction RatesThe Journal of Chemical Physics, 1936