Polypropylene (PP)/montmorillonite (MMT) nanocomposites were prepared by the esterification of propylene-g maleic anhydride (MAPP) with MMT modified with alpha,omega-hydroxyamines. The structural characterization confirmed the formation of ester linkages and the interaction between the silicate layers. In particular, X-ray diffraction patterns of the modified clays and MAPP/MMT composites showed 001 basal spacing enlargement as great as 0.14-0.62 nm according to the type of alpha,beta-hydroxyamine. Thermal characterization by thermogravimetric analysis for the composites revealed increased onset temperatures of thermal decomposition. The melting peak temperature decreased, and the crystallization peak temperature increased; this indicated that MMT retarded the crystallization of MAPP. Compounding PP with MAPP/MMT composites enhanced the tensile modulus and tensile strength of PP. However, the elongation at break decreased drastically even when the MMT content was as low as 0.4-2.0 wt %. (c) 2005 Wiley Periodicals, Inc.