Contributions of dipolar relaxation processes and ionic transport to the response of liquids to electrical perturbation fields

Abstract

The objective of this work was to study the influence of small variations in the chemical structure on the molecular dynamics of liquids using as models bis(cyclohexylmethyl) 2-methyl- and dicyclohexyl 2-methylsuccinate. The dielectric behavior of the low molecular weight liquids was studied over a wide range of frequencies and temperatures. The results show that the temperature dependence of the dielectric strengths, relaxation times, and shape parameters of the secondary and glass liquid relaxations are very sensitive to the slight differences in the structures of the liquids. Significant changes take place in the dielectric strength of the beta relaxation in the glass liquid transition. Moreover, the temperature dependence of the beta relaxation exhibits Arrhenius behavior in the glassy state and departs from this behavior in the liquid state. Special attention is paid to the temperature dependence of low-frequency relaxations produced by the motion of a macrodipole arising from charges located near the liquid-electrode boundaries.