Grafting of methyl methylacrylate onto isotactic polypropylene film using supercritical CO2 as a swelling agent

Grafting of methyl methacrylate (MMA) onto isotactic polypropylene (iPP) film was carried out by free radical polymerization using supercritical (SC) carbon dioxide (SC CO₂) as a solvent and swelling agent. The iPP film was first impregnated with the monomer MMA and initiator benzoyl peroxide (BPO) using SC CO₂ at 308.15 K. After releasing CO₂, the MMA molecules in the film were grafted onto the iPP at a higher reaction temperature. Using this method, the grafting level and the morphology can be controlled by the soaking time, pressure and concentrations of MMA and BPO in the fluid phase. 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).