Compatibilizers for thermotropic liquid crystalline polymer/polyethylene blends prepared by reactive mixing

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 300degreesC. 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.