Characterization of Dominant Hydrogen Bonded Complex Structures of Dielectric Polarization and Viscous Flow Processes in Glycerol–Formamide Binary Mixtures

Abstract

The static permittivity and viscosity of glycerol–formamide (Gly–FA) binary mixtures were measured at eleven concentrations over the entire composition range and at temperatures T=288.15, 303.15, 318.15 and 333.15 K. The excess static permittivity and excess viscosity of the mixtures were determined using the mole-fraction additive mixture law. Results indicated that the molecular dielectric polarization in Gly–FA mixtures is governed by 1:1 complexes with a decrease in number of H-bonded parallel aligned dipolar ordering at all of the investigated temperatures. The 2Gly:FA complexes facilitate the viscous flow process and the number of these complexes decreases with increasing temperature. The apparent activation energy of viscous flow, determined from Arrhenius plots, increases with increases of the Gly concentration in the mixtures. The electric-field-induced increment of the Helmholtz free energy and the entropy of these binary mixtures were determined from the temperature dependence of the static permittivity and its derivative, respectively.