Abstract
Novel block copolymers of a lyotropic polyamide (PBTA) and two amorphous polyimides (PI) were prepared, and were characterized to exhibit liquid-crystalline behavior. The rheology of PBTA and its copolymers were studied by a cone-and-plate rheometer. Additionally, the experimental relationship between shear viscosity and shear rate could be fitted by power-law model for isotropic solutions and Carreau model for anisotropic solutions. Moreover, solution processing of PBTA homopolymer and PBTA/PI block copolymers was carried out by a wet spinning apparatus. PBTA fibers were spun from anisotropic solutions (C>Ccr) and PBTA/PI copolymer fibers from isotropic solutions (C<Ccr). The tensile strength and modulus of copolymer fibers were found to locate between those of the PBTA fiber and the PI fiber. Take-up speed was varied during the spinning process for investigating the influence of draw ratio to the mechanical properties of the spun fibers. Liquid-crystalline textures could be observed in the resultant PBTA fibers under a polarized optical microscope. The morphology of all spun fibers was also present in the study.