Compatibilizers for Thermotropic Liquid Crystalline Polymer/Polyethylene Blends Prepared by Reactive Mixing

Robert Weiss, The University of Akron

Abstract

This paper describes the effects of composition and processing conditions on the efficiency of the compatibilizer prepared from a thermotropic liquid crystalline polymer (TLCP) and the sodium salt of a poly(ethylene-co-r-acrylic acid) ionomer (EAA-Na) in TLCP/low-density polyethylene (LDPE) blends and TLCP/high-density polyethylene (HDPE) blends. The TLCP-ionomer graft copolymer formed by a melt acidolysis reaction effectively reduced the interfacial tension between TLCP and polyethylene, which improved impact strength and toughness of the compatibilized blends. Higher processing temperatures for the reactive extrusion produced a more efficient compatibilizer, presumably due to increased graft-copolymer formation, but the reaction temperature had little effect on the impact strength of compatibilized blends for temperatures above 300°C. The addition of the compatibilizer to TLCP/LDPE blends significantly increased the melt viscosity due to increased interfacial adhesion. The TLCP/EAA-Na ratio used to prepare the compatibilizer had little effect on the performance of the compatibilizer. Although the compatibilizer can be prepared in situ by blending and extruding a ternary blend of TLCP/EAA-Na/polyethylene, pre-reacting the compatibilizer resulted in blends with improved toughness and elongation.