Abstract: The effects of comonomer and initiators with different halftime on the melt grafting process of polypropylene with malic anhydride were investigated in a twin screw reactive extruder. It showed that the preaddition of comonomer could effectively reduce the crack of macromolecular radicals during the melt grafting process. The addition of peroxide with different half time through different feed throats showed an excellent synergistic effect, which could greatly improve the grafting efficiency of MAH and reduce its residue. In a glass fiber reinforced PP system, a loading of 1.6 % of our PP-g-MAH may achieve the same performance using 3 % of traditional PP-g-MAH. Thus the heat resistance was enhanced.

Key words: polypropylene, maleic anhydride, reacting extrusion , grafting degree