Compatibilizing effect of styrene-maleic anhydride copolymer on the properties of polyamide-6/liquid crystalline copolyester composites

Abstract

Liquid crystalline polymer–polyamide-6 (LCP/PA6) composites containing 20 wt % LCP content were compatibilized by a random styrene–maleic anhydride copolymer (RSMA). The blending was performed via extrusion followed by injection molding. The LCP employed was a commercial copolyester, Vectra A950. The dynamic mechanical (DMA), rheological, thermal, and mechanical properties as well as the morphology of the composites were studied. The DMA and rheological results showed that RSMA is an effective compatibilizer for LCP/PA6 blends. The mechanical measurements showed that the stiffness, tensile strength, and toughness of the in situ composites are generally improved with increasing RSMA content. However, these mechanical properties deteriorated considerably when RSMA content was above 10 wt %. The drop-weight dart impact test was also applied to analyze the toughening behavior of these composites. The results show that the maximum impact force (Fmax) and crack-initiation energy (Einit) tend to increase with increasing RSMA content. From these results, it appeared that RSMA prolongs the crack-initiation time and increases the energies for crack initiation and impact fracture, thereby leading to toughening of LCP/PA6 in situ composites. Finally, the correlation between the mechanical properties and morphology of the blends is discussed. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 1964–1974, 2000