Open-cell photoacoustic investigation of the thermal effusivity of liquid crystals

We report the use of an open photoacoustic cell configuration for the evalu ation of thermal effusivity of liquid crystals. Initially, the method is ca librated using water and glycerol as transparent liquid samples, and the ro le of thermal conductivity of these liquids on the photoacoustic signal amp litude is discussed. To demonstrate the application of the present method f or the evaluation of thermal effusivity of liquid crystals, we have used ce rtain multicomponent nematic liquid crystal mixtures, namely BLOW, BL002, B L032, and BL035. Each of these liquid crystal mixtures contains four to nin e components and are primarily based on the cyanobiphenyl structure. The me asured values of thermal effusivity of BLOW and BL002 were found to be almo st the same, but differ from those of BL032 and BL035, which implies a diff erence in composition of the latter two from the former two mixtures. (C) 2 001 Society of Photo-Optical Instrumentation Engineers.