THE 1ST NORMAL-STRESS DIFFERENCE IN SHEAR OF NEMATIC LIQUID-CRYSTALS

The first normal-stress difference in shear flow of low-molecular-weight nematics is calculated from the Leslie-Ericksen theory. It is shown that, depending on the boundary orientation, the stress difference is either always negative, always positive or changes from negative to positive with increasing shear stress. This investigation was prompted by recent experimental studies demonstrating negative values of the first normal-stress difference for polymeric liquid crystals.