Dielectric relaxation in hydroxypolyesters

Abstract

Dielectric spectra of a hydroxypolyester (I) and an imide-modified hydroxypolyester (II) are presented. In both cases two clearly defined zones of relaxation are shown. At the high-temperature side of the spectrum the α relaxation zone is produced by micro-Brownian motion of the main backbone and by free charges, and below room temperature, a complex β secondary relaxation zone, showing indications of structure, is detected. Detailed analysis of the subglass relaxation zone is given and activation energies from an Arrhenius plot (In f vs. T^–1) are calculated for both polymers. By application to the low-frequence (high-temperature) side of the α relaxation of a transformation which converts permittivity ε* into polarizability α* a new relaxation peak appears; this is attributed to the conductivity in the liquid state.