On general properties of phenomenological and state coefficients for isotropic viscoanelastic media

The aim of this work is the study of general properties of phenomenological and state coefficients in a thermomechanical model for viscoanelastic media proposed by one of us (VC), in which cross-effect between viscous and inelastic flow is neglected. In particular, after the specification of the low and high frequencies region, under physical considerations characterized by limiting the values of some functions connected to mechanical phenomena, generally valid behaviour for phenomenological and state coefficients as function of the frequency are deduced. It has been possible, from the entropy production, to determine some characteristics of the coefficients as function of frequency in order that this principle is satisfied. The application of the so obtained results to a polymeric material as PolyIsobutilene in these regions in which, in a first approximation, the medium shows a linear behaviour, confirms our deductions.