Thermal behavior and morphology of polyamide 6 based multicomponent blends

The thermal behavior and morphology of multicomponent blends based on PA6, polyamide 6 (PA6)/styrene-acrylonitirle copolymer (SAN), PA6/acrylonitrile-butadiene-styrene terpolymer (ABS), and their compatibilized blends with styrene-acrylonitrile-maleic anhydride copolymer (SANMA) were studied using DSC and SEM. The blends were prepared in a twin-screw extruder under similar processing conditions, keeping the PA6 content fixed at 50 wt %. It was found that, in all the blends, the second component had a nucleating effect and improved the overall degree and rate of crystallization of PA6, whereas addition of a compatibilizer slightly diminished these effects and resulted in significant changes in the blend morphology. The nucleating effect and consequent changes in the crystallization behavior was attributed to the presence of SAN, which is a common component in all the blends. The T-g of PA6 in the blends with a cocontinuous morphology, due to the connectivity between the phases, is higher than in the blends with a disperse-type morphology. The compatibilized blends have a lower crystallization rate and nucleation ability with a cocontinuous morphology, whereas the uncompatibilized blends have a higher crystallization rate with a higher nucleation ability and a disperse and/or a coarse cocontinuous Morphology. (C) 2002 Wiley Periodicals, Inc.