Dielectric relaxation studies of acetonitrile/propylene glycol and their binary mixtures

Abstract

Dielectric relaxation spectra in the frequency range 0.02 < ν/GHz < 20 have been collected for propylene glycol (PG), acetonitrile (AN) and their binary mixtures between 303 K-323 K. The average relaxation times have been calculated by the Cole-Davidson and Cole-Cole relaxation models. The experimental determined values of static dielectric permittivity (ε₀), relaxation time (τ), excess permittivity (ε^E) and excess inverse relaxation time (1/τ)^E show smooth temperature dependence. The larger relaxation time values of propylene glycol when compared to acetonitrile are due to the co-operative process of multimers with O-H-O linkage and also the steric hindrance behavior phenomena. The activation entropy (ΔS*), activation enthalpy (ΔH*), Kirkwood correlation factor (g_f), Helmholtz energy (ΔF^E) parameters have also been determined for propylene glycol and acetonitrile and the results have been correlated.