Rheological and Rheo-Optical Studies with Nematogenic Solutions of a Rodlike Polymer: A Review of Data on Poly (Phenylene Benzobisthiazole)
Rheological and rheo-optical studies on isotropic and nematic solutions of poly (1,4-phenylene-2, 6-benzobisthiazole), PBT, are reviewed. The linear visco-elastic behavior is compared with theoretical models for the isotropic solutions. A BKZ-type constitutive equation coupled with an experimentally determined distribution of relaxation times is found to represent the nonlinear viscoelastic data reported for the isotropic data; comparisons with theoretical models are made. With the nematic solutions, nonlinear viscoelastic behavior is found even for very slow shearing deformations. This behavior may be related to orientation effects at the bounding surfaces. For more rapid shearing deformations, the bulk of the fluid is strongly oriented, similar to the orientation obtained in the isotropic fluid at high rates of shearing deformation. Comparisons are made among a number of rheological properties for isotropic and nematic solutions for the latter flows.
KeywordsRheological Property Nematic Phase Creep Compliance Methane Sulfonic Acid Elongational Viscosity
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