Viscosity and surface-tension measurements on cyanobenzylidene octyloxyaniline using propagating capillary waves: Critical behavior

The shear viscosities and surface tension of a liquid crystal CBOOA (cyanobenzylidene octyloxyaniline) were measured by the use of the technique of generating and detecting surface waves (capillary waves) developed by the authors. For the wave propagation perpendicular to the direction, the surface tension $\sigma$ decreased sharply upon entering into the smectic-$A$ phase. When the waves propagate parallel to the director, the attenuation due to the diverging viscosity ${\eta }_3$ near the nematic to smectic-$A$ transition became so large that measurements in the smectic phase were not possible. The viscosity ${\eta }_3$ was found to diverge as ${(T-T_c)}^{-\nu }$, where $\nu =1.0\mathrm{}\pm 0.1$ at 200 Hz and $\nu =0.83\mathrm{}\pm 0.15$ at 400 Hz.