Modification of isotactic polypropylene film by grafting of acrylic acid using supercritical CO2 as a swelling agent

Modification of isotactic polypropylene (iPP) film was carried out by grafting of acrylic acid (AA) onto its backbone using supercritical (SC) CO2 as a solvent and swelling agent. The iPP film was impregnated with the monomer AA and benzoyl peroxide initiator using SC CO2 at 308.15 K, followed by thermal polymerization of AA within SC CO2-swollen iPP film, resulting in iPP-g-PAA composites. The degree of grafting can be controlled by variation of the soaking time, pressure, concentrations of monomer and initiator in the fluid phase, reaction temperature, and time. The morphology and structure of the products were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, differential scanning calorimetry, and wide angle X-ray diffraction.