Viscoelastic and thermodynamic properties of short chain polymer melts with van der Waals interactions near the glass transition
Abstract
As the temperature of the polymer melt interacting with a Lennard Jones potential is lowered, the system undergoes a transition that is akin to gelation but can be seen as a glass transition. We consider several signatures of the transition, as determined by a molecular dynamics study of short, non-entangled chains (N=10). Of particular interest is the onset of rigidity. The shear modulus is sensitive to the applied deformation which determines the initial stress imparted to the system and the subsequent structural relaxation. Comparisons are made of values obtained by taking the limit G_eq=limt arrow ∞ G(t), where G(t) is the stress autocorrelation function, with those calculated by performing a simple shear deformation. We also look at the shear rate dependence of the viscosity both above and below the glass transition using a non-equilibrium molecular dynamics approach. Finally, we discuss the dependence of the final state on the preparation of the sample and the marked drop of the specific heat at the transition, with lowering temperature.
- Publication:
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APS March Meeting Abstracts
- Pub Date:
- March 2004
- Bibcode:
- 2004APS..MARU31006W