DIELECTRIC METHOD FOR DETERMINING THE ROTATIONAL VISCOSITY IN THICK SAMPLES OF FERROELECTRIC CHIRAL SMECTIC-C-STAR LIQUID-CRYSTALS

An alternative method, based on dielectric measurements on thick samples, for determining the Goldstone-mode rotational viscosity and the twist elastic constant of ferroelectric, chiral smectic-C* liquid crystals is presented. By the use of this method the temperature dependence of these quantities for p-decyloxibenzilidine-p-amino-1-methylpropyl-cinamate (DOBA-1-MPC) and p-n-decyloxybenzylidine-p-amino-2-methyl-butyl-cinamate (DOBAMBC) has been determined. An Arrhenius-type behavior of the Goldstone-mode rotational viscosity was obtained with activation energies =0.33 eV for DOBA-1-MPC and =0.51 eV for DOBAMBC. © 1990 The American Physical Society.