Maleic anhydride functionalized acrylonitrile-butadiene-styrene (ABS-g-MA) copolymers were prepared via an emulsion polymerization process. The ABS-g-MA copolymers were used to toughen polyamide 6 (PA-6). Fourier transform infrared results show that the maleic anhydride (MA) grafted onto the polybutadiene phase of acrylonitrile-butadiene-styrene (ABS). Rheological testing identified chemical reactions between PA-6 and ABS-g-MA. Transmission electron microscopy and scanning electron microscopy displayed the compatibilization reactions between MA of ABS-g-MA and the amine and/or amide groups of PA-6 chain ends, which improved the disperse morphology of the ABS-g-MA copolymers in the PA-6 matrix. The blends compatibilized with ABS-g-MA exhibited notched impact strengths of more than 900 J/m. A 1 wt % concentration of MA in ABS-g-MA appeared sufficient to improve the impact properties and decreased the brittle-ductile transition temperature from 50 to 10 degrees C. Scanning electron microscopy results show that the shear yielding of the PA-6 matrix was the major toughening mechanism. (C) 2008 Wiley Periodicals, Inc.