In situ small-angle light scattering analysis of texture in shearing liquid crystal polymers

Small-angle light scattering (SALS) has proven to be an effective tool for probing the complex microstructure present in liquid crystal polymers (LCPs) under shear flow. The flow SALS technique probes structures on the length scale of microns which, in the case of LCPs, corresponds to the defect texture. In this work, a model lyotropic LCP system, poly({gamma} benzylglutamate) (PBG) dissolved in m-cresol, has been investigated under steady state flow over several decades in shear rate. Several different features of the SALS patterns are identified and the influence of shear rate on these different features and relationship to observed microstructures and rheological behavior are discussed. The results of this work must be incorporated into texture-based models of the rheological behavior of LCPs; models which are necessary for the intelligent design and processing of LCP and LCP-based materials.