Temperature-dependent dielectric relaxation study of polyhydric alcohols (propane-1,3 and 1,2-diol) using a TDR technique

Abstract

The complex dielectric permittivity spectra of 1,2-propanediol, 1,3-propanediol and its binary mixtures with water have been studied as a function of frequency (10 MHz–30 GHz) and temperature. The dielectric relaxation parameters i.e. static dielectric constant and relaxation time were obtained by using non-linear least square fit method. The static dielectric constant of 1,3-propanediol is larger than the corresponding value for 1,2-propanediol. The intermolecular hydrogen bonding of 1,2-propanediol–water and 1,3-propanediol–water has been discussed using Kirkwood correlation factor and thermodynamic parameters. The activation energy decreases with increased water content in the mixture as expected from the Arrhenius behaviour. The dielectric constant for mixture has been fitted to Bruggeman mixture formula in non-linear case.