PREPARATION AND PROPERTIES OF SELF-REINFO RCED POLYPROPYLENE LCP BLENDS/

A high-speed and potentially economic method of creating a composite m aterial of PP with LCPs was explored. In line with the literature on s elf-reinforced blends, the LCPs were dispersed in the PP matrix in a c onventional extrusion process and subsequently drawn in order to accom plish highly uniaxial molecular orientation of the LCP fibres. The hig hest mechanical properties were found after rapid cooling of the self- reinforced blend, which was optimally exploited in thin filaments wher e cooling was fast enough to prevent fibre breakup and orientation rel axation. To enable the production of extrudates that are sufficiently thick to be cut into self-reinforced pellets a fused multi-filament te chnology was developed. In this technology, multiple thin filaments we re extruded/drawn and rapidly cooled to a temperature between the crys tallization temperatures of the LCP and PP. After solidification of th e LCP, the individual filaments were fused to form a single multifilam ent strand which was further cooled to room temperature. The thick LCP -reinforced PP strands were cut into pellets and used in injection- an d compression molding processes, This processing took place between th e melting temperature of the PP and the LCP, with retention of the asp ect ratio and the molecular orientation of the LCP fibres.