A maleic anhydride grafted propylene-butadiene copolymer (MPPB) was prepared. Fourier transform infrared spectroscopy and H-1-NMR results indicate that the maleic anhydride molecules reacted with the double bond in the butadiene unit of the propylene-butadiene copolymer (PPB), and the grafting percentage increased with the butadiene content in the initial copolymer. The gel permeation chromatography results show that the introduction of butadiene in the copolymer prevented the degradation of PPB. The MPPB was applied in polypropylene (PP)/styrene-butadiene-styrene triblock copolymer (SBS)/organophilic montmorillonite (OMMT) composites as a compatibilizer. In the presence of 10-phr MPPB, the impact strength of the composite was improved by about 20%. X-ray diffraction patterns indicated the formation of the beta-phase crystallization of PP in the presence of MPPB, and a significant decrease in the spherulite size was observed. Transmission electron microscopy (TEM) images showed that the OMMT was better dispersed in the matrix upon the inclusion of MPPB. A better distribution of the rubber phase and a rugged fracture surface were observed in the scanning electron microscopy images as the MPPB proportion was increased. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 114: 1820-1827, 2009