Rotational viscosity γ1 of nematic liquid crystals

Abstract

The rotational viscosity coefficients γ1 are measured with the rotating field method as a function of temperature in the nematic phases of 4-methoxybenzylidene-4′-n-butylaniline, 4-n-pentyl-, and 4-n-octyl-4′-cyanobiphenyl, of the eutectic mixture of two 4-n-pentylphenyl 4-alkoxybenzoates and of the eutectic mixture of the two isomers of 4-methoxy-4′-n-butylazoxybenzene. Equations are proposed which describe the temperature dependence very well. The Leslie coefficients αi are calculated from the γ1 values and recently measured shear viscosity coefficients.