Phase transition studies of some cholesteric liquid crystals and their mixtures using dielectric, optical transmittance and density measurement techniques

Investigations of the phase transitions in cholesteryl oleyl carbonate, cho lesteryl stearate and their mixtures have been made by measuring dielectric parameters, (epsilon') and (epsilon "), percentage optical transmittance a nd density in the temperature range of 15-85 degrees C. The study of all th ese parameters clearly indicates sharp discontinuities at transition temper atures exhibiting solid-cholesteric and cholesteric-isotropic phase transit ions. Also the transition temperatures for both solid-cholesteric and chole steric-isotropic transition vary with concentration of cholesteryl stearate and show almost a linear behaviour. (C) 2000 Elsevier Science Ltd. All rig hts reserved.