Conventional theories of glass transition are focussed oil reproducing the thermodynamic and dynamic properties of the structural alpha-process. However, in the last decade a class of secondary relaxations, called the Johari-Goldstein (JG) beta-relaxations. has attracted attention in view of the existence of various correlations and similarities of its properties with the structural alpha-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 beta-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 beta-relaxation are reported. In particular, these connections indicate that, like the structural relaxation, the JG beta-relaxation is entropy and volume dependent. The experimental facts are consistent with the results of the coupling model. (C) 2009 Elsevier B.V. All rights reserved
Does the entropy and volume dependence of the structural alpha-relaxation originate from the Johari-Goldstein beta-relaxation?
CAPACCIOLI, SIMONE;LUCCHESI, MAURO;ROLLA, PIERANGELO;
2009-01-01
Abstract
Conventional theories of glass transition are focussed oil reproducing the thermodynamic and dynamic properties of the structural alpha-process. However, in the last decade a class of secondary relaxations, called the Johari-Goldstein (JG) beta-relaxations. has attracted attention in view of the existence of various correlations and similarities of its properties with the structural alpha-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 beta-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 beta-relaxation are reported. In particular, these connections indicate that, like the structural relaxation, the JG beta-relaxation is entropy and volume dependent. The experimental facts are consistent with the results of the coupling model. (C) 2009 Elsevier B.V. All rights reservedI documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
