Thermodynamic interpretation of the scaling of the dynamics of supercooled liquids

TL;DR

This paper derives a thermodynamic interpretation of the scaling law for relaxation times in supercooled liquids, linking the scaling exponent to the Gruneisen constant and fitting experimental data across various materials.

Contribution

It revises the entropy model of glass transition dynamics to derive a new expression for relaxation time scaling, connecting it to thermodynamic properties.

Findings

The scaling law tau=f(T,V^g) is derived from a revised entropy model.

The scaling exponent g is identified with the Gruneisen constant.

The model accurately fits experimental data for various glass-formers.

Abstract

The recently discovered scaling law for the relaxation times, tau=f(T,V^g), where T is temperature and V the specific volume, is derived by a revision of the entropy model of the glass transition dynamics originally proposed by Avramov [I. Avramov, J. Non-Cryst. Solids 262, 258 (2000).]. In this modification the entropy is calculated by an alternative route, while retaining the approximation that the heat capacity is constant with T and P. The resulting expression for the variation of the relaxation time with T and V is shown to accurately fit experimental data for several glass-forming liquids and polymers over an extended range encompassing the dynamic crossover. From this analysis, which is valid for any model in which the relaxation time is a function of the entropy. we find that the scaling exponent g can be identified with the Gruneisen constant.