Influence of Cohesive Energy on the Thermodynamic Properties of a Model Glass-Forming Polymer Melt

Published

November 8, 2016

Author(s)

Jack F. Douglas, Wensheng Xu, Karl Freed

Abstract

We systematically investigate the thermodynamic and dynamic properties of a model glass-forming (GF) polymer melt by molecular dynamics simulation over a wide range of pressures (P) and temperatures (T). We first analyze the density, thermal expansion coefficient, compressibility (estimated from the static structure factor), and structural relaxation time τ (determined from the self-intermediate scattering function). We then determine the characteristic temperatures and fragility of glass-formation as a function of P. All characteristic temperatures of glass-formation increase with P in our non-associating polymer melt, while the fragility of glass-formation decreases with P. These trends accord with common experimental observations for non-associating fluids and predictions from the generalized entropy theory (GET). We further show that all our simulation data for τ as a function of P can be described by a universal scaling function that formally extends the Vogel-Fulcher-Tamman equation to variable P. This universal scaling again accords with experiment and the GET predictions.

Citation

The Journal of Chemical Physics

Pub Type

Journals

Keywords

pressure, glass-formation, dynamic heterogeneity, string model, generalized entropy theory

Citation

Douglas, J. , Xu, W. and Freed, K. (2016), Influence of Cohesive Energy on the Thermodynamic Properties of a Model Glass-Forming Polymer Melt, The Journal of Chemical Physics (Accessed April 25, 2024)