DIRECT DETERMINATION OF 5 INDEPENDENT VISCOSITY COEFFICIENTS OF NEMATIC LIQUID-CRYSTALS

A novel experimental procedure combining the measurement of the flow velocity and the change in birefringence induced by laminar flow in a magnetic field has been used to determine the complete set of the five independent shear-viscosity coefficients of nematic liquid crystals. The anisotropy of the magnetic susceptibility is obtained as well. Results are reported for p'-methoxybenzylidene-p-n-butylaniline (MBBA), p-n-hexyloxybenzylidene-p'-aminobenzonitrile (HBAB), and a 1:1:1-molar mixture of HBAB with p-n-butoxybenzylidene-p'-aminobenzonitrile and p-n-octanoyloxybenzylidene-p'-aminobenzonitrile.