Shear and rotational viscosity coefficients of two nematic liquid crystals

Abstract
A new method for the measurement of the shear viscosity coefficients η1, η2, and η3 of nematic liquid crystals is described. A detailed discussion of all sources of errors shows that reliable data can be obtained with this method. Measurements of the shear and rotational viscosity coefficients of a broad range nematic liquid crystal mixture of azoxy benzenes and for octyloxycyanobiphenyl with a transition to a smectic A phase are presented. The results are discussed in the framework of some theories.