Polycarbonate (PC) was blended with a semiflexible thermotropic liquid crystalline polymer (STLCP) and polycarbonate (PC) or a commercial copolyester (Vectra A950). The STLCP was synthesized to have long flexible spacers in a main chain. Fiber spinning and drawing was carried out by an Instron Capillary Rheometer equipped with a take-up apparatus. Mechanical, rheological properties and morphology were investigated by using Instron tensile tester, Rheometrics Dynamic Spectrometer, scanning electron microscope. Tensile modulus of PC/STLCP blend increased with STLCP content, while that of PC/Vectra blend increased up to 10% and then dropped with content. The aspect ratio (L/D) of the fibers was also estimated by using the Halpin-Tsai equation. It was found out that the drawn fibers with high draw ratios contained numerous fine fibrils with nearly infinite aspect ratio, and the modulus increased linearly with STLCP volume fraction as expected. That is, the relationship between modulus and volume fraction obeyed the mixing rule for continuous fibril reinforcement.
In the extrudates, the aspect ratio of PC/STLCP was larger than that of PC/Vectra. Deformation extent of the two blends during fiber spinning were compared through dimensionless parameters, the Weber number (We) and viscosity ratio, concerning with the deformation of dispersion phase. In order to obtain the We, interfacial tensions of the blends were calculated by Oldroyd model and compared them with the rheological data. The We of PC/STLCP was larger than that of PC/Vectra, but the viscosity ratio of the former was less than that of the latter. This was consistent with the results of aspect ratio estimated from Halpin-Tsai equation.