Viscosity measurements of nematic-polymer liquid crystal mixtures by light scattering

It is shown that the fluctuations in the intensity of light transmitted by planar aligned nematic liquids between polarizers is determined by the rotational viscosity alone at sufficiently high frequency. The technique is applied to the determination of the viscosity of polymer liquid crystal mixtures. The most viscous mixture which was successfully aligned (60 per cent polymer) has a viscosity 230 times larger than the cyanobiphenyl monomers.