Dielectric relaxation studies on binary mixtures of alcohols with DMSO using TDR

This study investigates the dielectric behavior of monohydric alcohols (primary, secondary, tertiary) in binary mixtures with dimethyl sulfoxide (DMSO). Time-domain reflectometry (TDR) was employed across a frequency range of 10 MHz to 30 GHz to determine the complex permittivity at 25 °C. This allowed for a comprehensive analysis of molecular interactions and dipolar relaxation dynamics within the mixtures. The measured dielectric spectra were fitted using the Cole–Davidson model, from which the static dielectric constant and relaxation time were precisely evaluated. Furthermore, the excess dielectric permittivity and excess inverse relaxation time were analyzed to quantitatively assess deviations from ideal mixing behavior and to elucidate cooperative dipole interactions within these systems. To gain further insights into the orientation correlation of dipoles and the effective volume of components in the mixture, the Kirkwood correlation factor and Bruggeman factor were also determined and discussed. These parameters provide critical information regarding the short-range molecular ordering and the extent of molecular association in the binary solutions.