Article ID Journal Published Year Pages File Type
1485125 Journal of Non-Crystalline Solids 2007 8 Pages PDF
Abstract

Published dielectric and shear data of six molecular glass formers and one polymer are evaluated in terms of a spectrum of thermally activated processes, with the same barrier density for the retardation spectrum of shear and dielectrics. The viscosity, an independent parameter of the fit, seems to be related to the high-barrier cutoff time of the dielectric signal, in accordance with the idea of a renewal of the relaxing entities after this critical time. In the five cases where one can fit accurately, the temperature dependence of the high-barrier cutoff follows the shoving model. The Johari–Goldstein peaks, seen in four of our seven cases, are describable in terms of gaussians in the barrier density, superimposed on the high-frequency tail of the α-process. Dielectric and shear measurements of the same substance find the same peak positions and widths of these gaussians, but in general a different weight.

Related Topics
Physical Sciences and Engineering Materials Science Ceramics and Composites
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