Temperature Dependent Microwave Dielectric Characterization of Associated Liquids

Resumo

The present paper reports static dielectric constants, densities, viscosities, and refractive indices of the binary mixtures of ethanol with DMSO measured at 303 K, 308 K, 313 K. These measured parameters are used to obtain the derived properties, such as the Bruggeman factor, the molar polarization, the excess molar volume, the excess viscosity, the excess static dielectric constant, and the excess molar polarization. The variation in magnitudes of these quantities with composition and temperature is used to discuss the type, strength, and nature of binary interactions. The excess parameters are fitted to the Redlich Kister (R-K) fit equation. The evaluated values of the excess dielectric constant and the excess molar polarization infer that deviations of their mixture values occur from the mole-fraction mixture law. The results confirm that there are dipole-dipole interactions between unlike molecules of ethanol+DMSO mixtures and that 1:1 complexes are formed. The excess static dielectric constant indicates that there is a decrease in the total number of parallel aligned effective dipoles that contribute to the mixture dielectric polarization. It is observed that the excess molar volume becomes more and more positive with the corresponding increase in the temperature. This observation certainly leads to the inference that the intermolecular interaction strength decreases with the temperature.