Ionic effects on the dielectric behaviour of liquid and glassy states of butane-1, 3-diol and glycerol

Abstract

The effects of electrolytes on the H-bond association in glycerol and butane-1,3-diol have been studied by measurement of their dielectric properties over a temperature range from their glassy to supercooled fluid states. The presence of ions decreases the equilibrium permittivity. This with the ion type and is not attributable entirely to the kinetic depolarization effects. The decrease in the degree of intermolecular H bonding or dipolar orientational correlation also contributes to the effects observed. The sub-T_g relaxation process appears as a low-temperature shoulder to the main peak. This shoulder becomes better resolved at high concentrations, mainly as result of less efficient packing of shorter, H-bonded chains and the reorientation of an increased number of dipolar ion-pairs. The permittivity of solutions at 77 K increases with the increase in their concentration owing to the increase in both the optical and infrared polarizabilities. The nature of H-bond association in pure liquids can be investigated by observing the effects of electrolytes on their electrical properties.