Shear Viscosity Measurements in CBOOA

The anisotropic shear viscosity of the liquid crystal CBOOA has been measured by observing the flow through a flat capillary. Uniform alignment was maintained by application of magnetic fields up to 85 kOe. In the nematic phase, five different measurements were made to determine the five independent coefficients. In the smectic phase, when the smectic planes were parallel to the capillary plates, the flow was nearly Newtonian and the temperature dependence had an Arrhenius behavior. When the smectic planes were parallel to the velocity and to the velocity gradient. The flow was non-Newtonian and rheopectic. This non-ideal behavior is attributed to the existence of nucleation of dislocations that can become pinned at the capillary walls.