Temperature-dependent dielectric relaxation study of binary mixture using the time domain reflectometry method

Abstract

Dielectric relaxation study of N,N-dimethylformamide (DMF) has been carried out with butylene glycol (BLG, i.e. 1,4-butanediol) at different temperatures. Time domain reflectometry in reflection mode has been used to measure the reflection coefficient in the frequency range from 10 MHz to 20 GHz. The dielectric parameters, static dielectric permittivity (ε 0) and relaxation time (τ), have been obtained by Fourier transform and least squares fit methods. The experimental results show non-linear variation in dielectric permittivity, and relaxation time with volume fraction of BLG confirms the structural formation due to the intermolecular interaction between DMF and BLG. The variations in excess permittivity (εE ), excess inverse relaxation times (1/τ) E and Kirkwood correlation factors (g eff ;g f ) for the binary mixtures have also been reported in this article.