Temperature dependence of dielectric relaxation of rigid polar molecules acetophenone, pyridine and their mixtures in dilute solutions of benzene

Abstract

The dielectric absorption studies of acetophenone, pyridine and their binary mixtures, both consisting of rigid molecules, have been studied at 8.93 GHz in the dilute solutions of benzene at different temperatures. The relaxation times, dipole moments, thermodynamical parameters, viz. free energy, enthalpy and entropy of activation have been calculated from the dielectric data. The relaxation time (1: 11) of the single component agrees well with literature values. The experimental values of relaxation time (1: 11) of the dipolar mixture have been compared with the theoretical values obtained by employing different methods. The non-linear behaviour of ~ 2 versus mole fraction is explained on the basis of solute­ solute molecular association between these two-polar rigid molecules. The values of the molar entropy for the relaxation process indicate that , the cooperative orientation of the molecules in the single component system is retained in the mixture also.