Rheo‐optical studies on aligned nematic solutions of a rodlike polymer

Rheo‐optical studies on shear deformation of well‐aligned nematic solutions of the rodlike poly (1,4‐phenylene‐2,6‐benzobisthiazole), PBT, are reported. Conoscopic microscopy was used to follow the director during shear, and during relaxation on cessation of flow. The results show that the molecules are not homogeneously aligned in shearing flow. Rather, various complex director field distortions may occur, depending on the relative orientation of the initial director to the flow direction. The results are compared quantitatively with predictions based on the Ericksen–Leslie constitutive equation for nematic fluids.