Anisotropic mechanical properties of a polymer nematic liquid crystal

A concentration dependence of elastic and viscous properties of nematic poly-γ-benzyl glutamate (PBG) was studied experimentally. The splay and bend constants are similar in magnitude, both linear in concentration. The twist constant is much smaller and constant. Viscosities exhibit large anisotropies. ${\gamma }_1$ and ${\eta }_c$ are roughly quadratic in concentration, ${\eta }_a$ is linear, while ${\eta }_b$ is constant. The data are self-consistently interpreted in terms of the theoretical models for nematics of semi flexible chains rather than those of rigid rods.