Optical anisotropy of a thermotropic liquid‐crystalline polymer in transient shear

A rheo‐optical apparatus, based on a linear shear rheometer, has been constructed to study the deformation of liquid–crystalline polymers. This apparatus uses optical techniques such as flow birefringence, small‐angle light scattering, and optical microscopic image analysis. The rheological responses were simultaneously measured under varying temperatures and deformation conditions. The modified Debye‐Bueche equation for scattering, in the nonspherically symmetrical form, was adapted to analyze small‐angle light‐scattering data. The orientation correlation lengths, determined by this method, reveal the deformation mechanism in nematic melts. Flow birefringence results are in agreement with the proposed mechanism.