Modification of isotactic polypropylene (iPP) films was carried out by grafting methyl acrylate (MA) onto its backbone using supercritical (SC) CO2 as a solvent and swelling agent at 308.15 K, followed by thermal polymerization of MA within supercritical CO2 (SC CO2)-swollen iPP film after releasing CO2, resulting in iPP-g-PMA composites. The grafting level can be controlled by the soaking time, pressure, concentrations of monomer and initiator in the fluid phase, reaction temperature and reaction time. The morphology and structure of the products were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and wide angle X-ray diffraction (WAXD). (C) 2003 Elsevier B.V. All rights reserved.