ON THE IN-SITU GENERATION OF REINFORCING FIBERS

A study has been made of the formation of the microstructure of a polypropylene (pp) and liquid crystal polymer (LCP) blend. The pp/LCP mixture was fed into a single-screw melt extruder, and polyblend fibers were made by extrusion of the melt through a spinneret plate. Samples of the melt were taken from various sections of the screw barrel, before and after the metering pump, before and after the mesh filter, before and after the die head, and in the as-made fibers. The microstructure of the LCP phase in the blend was studied with a hot-stage microscope. It was found that the dispersion of the LCP phase in the pp matrix was well completed before the metering pump. Planar flow and compressional strain in the metering pump had little influence on the LCP phase structure, but elongational strain in the mesh filter produced fine dispersion of the LCP phase. It was found that the LCP phase existed largely in spherical particles before the die-head entrance. Although the extensional flow in the die entrance deformed the LCP particles into thin droplets, further elongational strain below the die head is essential if thin and long LCP fibrils are required in the polyblend fibers. (C) 1994 John Wiley & Sons, Inc.