α-relaxation and the excess wing in polychlorinated biphenyls

Abstract

Dielectric spectra were obtained on three polychlorinated biphenyls, having glass temperatures $T_g$ differing by up to 48 deg. The shapes of the α-relaxation peaks were the same for all samples, as were the $T_g$-normalized temperature dependences of the relaxation times. The characteristic temperatures at which the relaxation times deviate from a Vogel-Fulcher dependence were also equivalent ${(T}_B\sim 1.14T_g).\mathrm{}$ However, the prominence of the high-frequency “excess” wing, while present in the spectra for all materials, was markedly different. This lack of correlation between the α relaxation and the excess wing suggests the two phenomena are distinct.