Microwave dielectric response of binary mixture of N,N-dimethylformamide with propylene glycol using TDR method

Abstract

Dielectric relaxation study of N,N-dimethylformamide (DMF) has been carried out with propylene glycol (PLG) at different temperatures. Time domain reflectometry (TDR) in reflection mode has been used to measure the reflection coefficient in frequency range of 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 nonlinear variation in dielectric permittivity and relaxation time with volume fraction of PLG confirm the structural formation due to the intermolecular interaction between N,N-dimethylformamide and PLG. The variation in excess permittivity (ε E), excess inverse relaxation times (1/τ)E, Kirkwood correlation factors (g eff, g f), activation enthalpy (ΔH) and entropy (ΔS) are also calculated to study the binary mixture interaction.