The grafting of maleic anhydride onto a granular polypropylene (PP) using supercritical CO-2 as a solvent and swelling agent was studied to prepare granular PP-g-MAH polymers.The factors affecting the graft degree of PP,such as the monomer content,initiator content,reaction temperature and reaction pressure were discussed.The maximum graft degree of PP with MAH in supercritical CO-2 medium was 5^23% under the optimal reaction conditions at 125℃ and 15 MPa for 5 h.By using the supercritical CO-2 technique the operation of grafting reaction and separation of products became simple and easy to deal with.The formation of PP-g-MAH grafting copolymer was evidenced by FTIR measurements.An absorption peak at 1720^6 cm -1 assigned to the stretching vibration of carbonyl groups was observed.DSC results indicated that the grafting gave almost no influence of T-g values,but may increase the crystallinity of PP.
