Relaxation processes in poly(2-chlorocyclohexyl acrylate) as studied by dielectric relaxation and mechanical relaxation spectroscopy

Abstract

[EN] A comparative study of the mechanical and dielectric relaxation spectra of poly(2-chlorocyclohexyl acrylate) (PCCHA) is reported. The spectra present a moderate subglass beta absorption, followed in increasing temperature order by a prominent alpha glass-rubber relaxation process. The distribution of activation free energies for the beta subglass relaxation is determined, from which average values of 14.0 kcal mol(-1)/6.94 cal mol(-1) K-1 and 10.5 kcal mol(-1)/1.83 cal mol(-1) K-1 are obtained for activation enthalpies/entropies of the mechanical and dielectric processes, respectively. The critical analysis of the H-1 MMR spectra and the modeling of the dielectric relaxation suggest that this absorption is mainly caused by conformational transitions about the C-CO bonds of the side groups. The fact that the exponent of the stretch function is similar for the alpha and beta relaxations seems to indicate that very Limited local processes produce the beta absorption.