Dielectric properties to 3 GHz of liquid crystal mixtures and several alcohols by time domain reflectometry

Studies have been made of the complex dielectric permittivities of mixtures of cholesteric liquid crystals and of a homologous series of normal alcohols. The dielectric spectroscopy was done by the method of time-domain reflectometry (TDR). The liquid crystals were cholesteryl alkanoates with cholesteric-isotropic transition temperatures of 19°C and 72°C. The 50 weight percent mixture has T_CI=32°C. This transition was investigated by TDR. In the case of the alcohols a simple quantum model has been developed to explain a systematic variation of the dielectric loss peaks versus molecular length. A comparison with experimental data indicates that all of the alcohols studied (up to C₁₂H₂₅OH, dodecanol) behave as fully extended molecules at the temperature at which librational motion goes over into rotation