STRUCTURE AND RHEOLOGY OF ARAMID SOLUTIONS - X-RAY-SCATTERING MEASUREMENTS

Preliminary results are presented on the orientational order in the lyotropic nematic phase of poly(4,4’-benzanilidyleneterephthalamide) in concentrated H2SO4, using synchrotron X-ray scattering, both during and after simple shear deformation. The average orientational order, as measured from the azimuthal peak width of the 003 reflection, is almost independent of the shear rate. This is contrary to the results obtained from microscopic observation, where the degree of orientation appears to increase with increasing shear rate. The development of the orientation, as determined by X-ray scattering, during a start-up experiment depends on the applied strain. This observed strain dependence is compared to an affine simple shear deformation model. The relaxation time of the shear-induced orientation decreases with increasing initial shear rate. During coagulation experiments the meridional reflections move to slightly smaller Bragg angles, indicating that chain stretching occurs. © 1990, American Chemical Society. All rights reserved.