Does the entropy and volume dependence of the structural α-relaxation originate from the Johari–Goldstein β-relaxation?

Abstract

Conventional theories of glass transition are focussed on reproducing the thermodynamic and dynamic properties of the structural α-process. However, in the last decade a class of secondary relaxations, called the Johari–Goldstein (JG) β-relaxations, has attracted attention in view of the existence of various correlations and similarities of its properties with the structural α-process. These experimental evidences suggest that the secondary process may play a fundamental role in glass transition, and any theory of glass transition would be incomplete until the inter-relations between the JG β-relaxation and the structural relaxation have been considered. In this paper, some significant experimental results showing several general and nontrivial connections between structural relaxation and JG β-relaxation are reported. In particular, these connections indicate that, like the structural relaxation, the JG β-relaxation is entropy and volume dependent. The experimental facts are consistent with the results of the coupling model.