Dielectric Properties of the Mixtures of Cholesterol and Cetyl Alcohol

Abstract

The phase diagram of the cholesterol-cetyl alcohol system was determined by means of optical microscopy, differential thermal analysis, and dielectric measurement. A mixture of cholesterol and cetyl alcohol took a liquid-crystalline state at a limited range of composition (25-45 mole% of cholesterol) although each of pure components did not take the liquid-crystalline state. The dielectric properties of the mixture was examined and the dielectric constant and the dielectric loss were found to take maximum values at the temperature where the fusion begins. Dielectric loss is mainly due to relaxation in the solid phase. In the range from the initial melting point to the final melting point of the solid, the mixtures have dielectric relaxation smaller than that of the solid phase. In the liquid crystal and the isotropic liquid phase, the mixture does not show dielectric relaxation so that the dielectric loss is due to conduction.