Dielectric relaxation in relation to viscosity of some organic molecules and some of their binary mixtures

The study of variation of dielectric relaxation time with the viscosity of the medium helps in drawing certain quantitative conclusions regarding molecular motion and intermolecular forces in liquids, liquid mixtures, dilute solutions and multi-component polar solutes in dilute solution. In the absence of a perfect empirical or theoretical equation for the variation of dielectric relaxation time with viscosity, the experimental investigations on different systems only can give an insight. In the present study the results of dielectric measurements carried out on samples of 2-chlorothiophene, 2-methyl benzaxazole, m-bromonitrobenzene, p-fluorophenyl acetonitile, p-bromonitrobenzene and 2-chloro-6-fluoro-benzaldehyde in dilute solutions in different mixed solvents (benzene + paraffin) and on binary mixtures (1:1) of p-fluorophenyl acetonitile + 2-butylphenol and 2-chloro-6-fluoro-benzaldehyde + o-ethylphenol, are reported. Different parameters determined using these dielectric measurements are also presented using different models and these studies indicate that the dielectric behavior at microwave frequencies favors the concept of dynamic viscosity and a single viscoelastic relaxation time for the system under study.