Influence of cohesive energy on relaxation in a model glass-forming polymer melt

Published

November 8, 2016

Author(s)

Jack F. Douglas, Wensheng Xu, Karl Freed

Abstract

The wide range of chemical compositions exhibited by polymer materials leads to materials having highly tunable cohesive energy strength epsilon, and many of the properties that make polymers so useful as structural and responsive materials in manufacturing and in living systems derive from this basic property. The problem of polymer materials design and characterization then inevitably leads to a consideration of how epsilon impacts the thermodynamic and relaxation properties of polymer liquids. Our initial paper systematically investigated the epsilon dependence of commonly measured thermodynamic properties of a model coarse-grained polymer melt by molecular dynamics simulation, while the present work focuses on the relaxation dynamics of the same model. After demonstrating that greatly influences the segmental relaxation time, as expected, we obtain a universal reduction of all our relaxation data in terms of an activated transport model in which the activation free energy is increased from its high temperature value by a factor precisely determined by the average extent of monomer cooperative motion in the polymer liquid.

Citation

Macromolecules

Pub Type

Journals

Citation

Douglas, J. , Xu, W. and Freed, K. (2016), Influence of cohesive energy on relaxation in a model glass-forming polymer melt, Macromolecules (Accessed April 25, 2024)