PHENOMENOLOGICAL AND STATE COEFFICIENTS IN VISCOELASTIC MEDIUM OF ORDER ONE (WITH MEMORY)

The aim of this work is to indicate a method to measure experimentally some phenomenological an state coefficients, and so to verify some inequalities that follow from principle of entropy production. In particular, we will consider the Kluitenberg-Ciancio model for a viscoanelastic medium of order one with memory and the relative rheological equation in which, neglecting cross effects between viscous and inelastic flow, four phenomenological an state coefficients appear. Assuming an harmonic deformation as cause and the stress as effect we will compare the solution of the Kluitenberg-Ciancio’s equation with a well known expression of the stress obtained, by experimentally considerations in the linear response theory, as function of the frequency of deformation at a constant temperature. This comparison will be able to determine the phenomenological an state coefficients as function of frequency dependent quantities experimentally measurable. This method will be applied to polymeric materials as Polyisobutilene.