Concentration effects on the rheology and texture of PBG/m-cresol solutions

In this work, the rheology of PBG/m-cresol systems is reevaluated with the specific goal of understanding the influence of concentration on low shear-rate rheology. Comparison of steady-state and transient rheology and the behavior after cessation of shear allow for the separation of the contributions to the stress from the nematic fluid and defect texture. Stress relaxations demonstrate that the textural contribution to the stress increases nonlinearly from 30% to 55% as the concentration increases from 12 to 37 wt %. Recoil shows a similar nonlinear trend in the magnitude of the ultimate recovered strain γ_∞. Stress relaxations and recoil, once normalized, have universal dynamics dependent only on γ̇_ot and independent of concentration. Two different regions of concentration are identified and correlated to a distinct change in the nature and behavior of the textural contribution to the stress.