Molecular alignment of polymer liquid crystals in shear flows. 1. Spectrographic birefringence technique, steady-state orientation, and normal stress behavior in poly(benzyl glutamate) solutions

The orientation state of liquid crystalline solutions of poly(benzyl glutamate) under shear flow was investigated and the relationship between the microscopic structure and the macroscopic mechanical rheological behavior is discussed. The flow birefringence observed in textured solutions under shear flow is always less than that measured in quiescent, defect-free monodomains of the solutions. At low shear rates, the birefringence is roughly constant and in the range of 53-63% of that observed in a monodomain; there is no evidence of a low-orientation , piled-polydomin structure