Effect of entropy on the dynamics of supercooled liquids: New results from high pressure data

TL;DR

This paper demonstrates that entropy master curves can be scaled by TV^g_G, revealing contributions from non-dynamic processes, and proposes a method to isolate the entropy component directly influencing supercooled liquid dynamics.

Contribution

It introduces a new scaling approach for entropy in supercooled liquids and a method to separate dynamic-relevant entropy from other contributions.

Findings

Entropy master curves scale with TV^g_G for various conditions.

The inequality g_G < g indicates additional entropy contributions.

A method to extract the entropy component linked to supercooled dynamics is proposed.

Abstract

We show that for arbitrary thermodynamic conditions, master curves of the entropy are obtained by expressing S(T,V) as a function of TV^g_G, where T is temperature, V specific volume, and g_G the thermodynamic Gruneisen parameter. A similar scaling is known for structural relaxation times,tau = f(TV^g); however, we find g_G < g. We show herein that this inequality reflects contributions to S(T,V) from processes, such as vibrations and secondary relaxations, that do not directly influence the supercooled dynamics. An approximate method is proposed to remove these contributions, S_0, yielding the relationship tau = f(S-S_0).