Distribution of Dielectric Relaxation Times in Glycerol— and Butanediol-1,3—n-Propanol Mixtures

Abstract

Dielectric relaxation times and their distribution have been measured in associated—associated mixtures of glycerol—n-propanol and butanediol-1,3—n-propanol. Measurements were made at temperatures selected for each concentration so as to give approximately constant relaxation times as a function of concentration. All mixtures exhibited one main relaxation process with a distribution of times of the Davidson—Cole form. The distribution parameter β increased only slightly over the concentration ranges of 0 to 67 mole % n-propanol in the butanediol mixture and 0 to 75 mole % n-propanol in the glycerol mixture. For concentrations above 67 and 75 mole % n-propanol, β increased rapidly to unity as a function of concentration. This behavior of the distribution of dielectric relaxation times is indicative of the influence of structural formation on the dielectric process in these liquid mixtures and demonstrates that the structure is characteristic of the pure glycerol and butanediol-1,3 for concentrations of n-propanol between zero and the values necessary for saturation of the diol and triol molecules. Above 67 and 75 mole %, the structure rapidly takes on the characteristic of the pure n-propanol.