THE RELATION BETWEEN SPINNABILITY OF THERMOTROPIC LIQUID-CRYSTALLINE POLYMERS AND THEIR SUBMICROMETER REINFORCING FUNCTION IN POLYMER BLENDS

Six thermotropic liquid-crystalline polymers (TLCPs) were spun on a CS I 194 Mini-Max extruder in their optimized spinning-temperature ranges . Based on the diameter and the diameter distribution of the resultant fibres, these TLCPs were classified into two groups with good and poo r spinnability, respectively. The viscosity ratio of TLCP to matrix re sin, eta(d)/eta(m), in the optimized spinning-temperature range was us ed as a parameter for controlling TLCP fibrillation in the resin matri x. For a TLCP having good spinnability, its morphology in different re sins was observed and correlated with the viscosity ratio in the range of 10(-2) to 10. With decreasing eta(d)/eta(m) from 16 to 0.05, the d ispersed TLCP phase changes from spheres through ellipsoids and short rods to fibrils. Under the same condition, i.e. in the eta(d)/eta(m), range of 0.01 to 0.1, TLCPs with good spinnability generate fibrils in injection-moulded samples, while poor spinnability ellipsoids and rod s only are generated. The results of image analysis show that two TLCP s with good spinnability generate fibrils of smaller diameters, narrow er diameter distributions and larger intrinsic aspect ratios. It is sh own that there is a correlation between the TLCP spinnability in air a nd TLCP fibrillation in the resin melt. This could be taken as a prere quisite for the achievement of submicrometre reinforcing with LCP fibr ils.