Dielectric Relaxation in Ethylene Glycol - Dimethyl Sulfoxide Mixtures as a Function of Composition and Temperature

Abstract

Using time domain reflectometry, the complex dielectric spectra between 10 MHz to 20 GHz has been mea- sured in the whole composition range at 10, 20, 30 and 40 o C for the binary mixtures of ethylene glycol and dimethyl sul- foxide. For all the mixtures, only one dielectric loss peak was observed in this frequency range. The relaxation in these mixtures can be described by a single relaxation time using the Debye model. A systematic variation is observed in dielectric constant (e0) and relaxation time (τ). The excess permittivity (e E ), excess inverse relaxation time (1/τ) E , Kirkwood correlation factor (g) and thermodynamic parameters viz. enthalpy of activation (∆H) and Gibbs free energy of activation (∆G) have been determined, to confirm the formation of hydrogen bonded homogeneous and heterogeneous cooperative domains, the dynam- ics of solute - solute interaction and the hindrance to molecular rotation in the hydrogen bonded glass forming ethylene glycol - dimethyl sulphoxide system.