Mixing History on the Morphology and Properties of Thermoplastic/LCP Blends

Abstract

Abstract Blends of poly(ethylene terephthalate) (PET) and polypropylene (PP) with several liquid crystalline polymers (LCPs) were successfully generated using a novel blending method, referred to as the dual-extruder mixing method. In this method, the matrix and LCP polymers were plasticated separately in two single-screw extruders. The melt streams were then joined together and blended in a Kenics static mixer containing 18 mixing elements. Strands (rods) and sheets of the blends were extruded using the above method. First, blends of thermoplastics with LCPs were successfully made using this method in which there is little or no overlap of the nominal processing temperatures. Second, the morphology of extruded strands from the dual-extruder mixing method was seen to consist of LCP fibrillar structures which were truly continuous running the length of the extrudate and further devoid of any skin-core type structure. Third, LCP fibril formation was seen to occur even when the LCP concentration was only 4 wt.-% in the blend. By contrast blends from the single-screw extrusion exhibited a distinct skin-core fibril-droplet type of structure.