Determination of the Viscosity Coefficients of the Liquid Crystal MBBA

Abstract An experimental procedure is described which allows the determination of the viscosity coefficients η1, η2, η3 and η12 for nematic liquid crystals as a function of temperature. Errors which arise from the surface and the flow alignment are discussed in detail. The measurements are performed on the nematic liquid crystal 4-methoxybenzylidene-4'-n-butyl-aniline (MBBA). At 25°C the viscosity coefficients are η1 = 0.1361, η2 = 0.0240, η3 = 0.0413 and η12 = -0.0181 Pa s.