Abstract

The aim of this work is to clarify some features of glass forming systems, such as temperature dependence of density, thermal expansion coefficient and shear viscosity. They are first discussed from the theoretical point of view and then experimentally tested for glycerol. The parameters y, interpreted as the effective number of degrees of freedom related to the a-relaxation process, and j, the specific volume occupied by heterogeneous nuclei, are introduced. Both they provide an explanation of the temperature dependence of density and thermal expansion coefficients in liquid, solid amorphous, glassy and crystal states.Furthermore, the relation between the macroscopic and microscopic definitions of fragility is showed and discussed.

Keywords: glass forming systems; density; thermal expansion coefficient; shear viscosity; temperature dependence; glycerol.