MICROSTRUCTURE FORMATION IN POLYBLENDS CONTAINING LIQUID-CRYSTALLINE POLYMERS

Based on theological data, two polyblends of poly(ether sulfone) (PES) and polycarbonate (PC) with a liquid crystalline polymer (LCP) as the dispersed phase were prepared by extrusion. The process of LCP microstructure formation was investigated by studying the morphology of the blend obtained from different sections of the extruder. The deformation of LCP domains is controlled by the viscosity ratio of the dispersed phase to the continuous phase (eta(d)/eta(m)). LCP domains in LCP/PES blend have been deformed into oriented fibrils, due to a viscosity ratio of 0.01. A quantitative comparison of LCP droplet sizes before and after the extruder die shows that the morphology of extrudates has been determined before the melt enters the die. After the die, the diameter and length to diameter ratio of LCP fibrils were increased by coalescence and further deformation by the action of extensional flow. The morphology of LCP/PES extrudates after remaining at quiescence within the die for different time intervals indicates that even after a 60 s residence, LCP domains retained their fibrillar structure in the blend and no significant recoiling and breakup of LCP fibril occurred.