Dielectric relaxation and thermodynamic study of Dimethylformamide/1,4-Butanediol binary mixtures in the temperature range 298K–323K

Abstract

In the present paper, the permittivity of Dimethylformamide (DMF) with 1,4-Butanediol (BD) binary mixtures are determined at the temperature range of 298 K–323 K in the microwave frequency. Dipole moment (μ), excess molar volume (VmE), partial molar volume (Vm,i), excess permittivity (εE), excess refractive index (nDE), excess inverse relaxation time (1/τ)ε, thermal expansion coefficient (αP), excess Helmholtz energy (ΔFE) are determined at different temperatures. Redlich-Kister polynomial equation is used to fit the excess parameters. Havriliak-Negami equation is used to analyse the relaxation time of the binary mixtures throughout the measured temperature range. The heteromolecular interaction between DMF and 1,4-Butanediol binary mixtures are interpreted in terms of Kirkwood correlation (geff) factor. The stability of the system is analysed from the activation energy (ΔG*), enthalpy (ΔH*) and entropy (ΔS*) parameters. The various mixing rules were applied in order to estimate the permittivity and refractive indices of the binary system at different temperatures.