A new analysis of the results of thermally stimulated measurements in polymers

Publisher Website
Google Scholar
Abstract
It is shown that the compensation law observed in thermally stimulated measurements (TSC and TSDC) between the activation energy E and the preexponential term τ0 in the Arrhenius equation for various polymers can be explained by a linear relation between the activation enthalpy ΔH‡ and entropy ΔS‡ of the process. When this relation is combined with the well-known rate theory, TSC or TSDC results with polymers indicate that both techniques yield very similar results. It is also deduced that they are especially sensitive to entropy changes in the polymers studied. This points out the non-negligible value of ΔS‡ in polymer relaxations, and this implies that the proper energy term describing a polymer relaxation is not E but a free-energy term ΔG. The relation between the Vogel–Tammann–Fulcher and rate theory equations is also made. The correlations between the ΔG, ΔH‡, and ΔS‡ values, and the polymer thermodynamic and morphological properties are also briefly discussed.