Rheological Hybrid Effect in LCP/Thermoplastic Blends with Different Inorganic Fillers

摘要

In the existence of a thermotropic liquid crystalline polymer (LCP), the melt viscosity of polycarbonate and polyamide decreases with increasing content of inorganic fillers such as glass fiber and glass bead. The viscosity of these ternary blends is not only lower than that of neat matrix resins and filled composites, but also lower than that of LCP/matrix resin blends. This phenomenon is termed as rheological hybrid effect with its definition of "a phenomenon in which the melt viscosity of a ternary polymer blend decreases with increasing filler loading, influenced by the minor polymer phase in the blend". The conditions for the occurrence of this hybrid effect are investigated thermodynamically and dynamically. The interfacial tension favors the migration of inorganic fillers to the vicinity of and into the LCP droplets. Then the elongational flow at the entrance of capillaries temporarily formed by bundles of glass fibers, and the rolling of glass beads aggregated promote the fibrillation of LCP. Thus in-situ generated LCP fibrils lubricate the melt and decrease the melt viscosity of the whole blend.