Abstract: Maleic anhydride (MAH), styrene (St), divinylbenzene (DVB), and an initiator (DCP) were embedded into polypropylene (PP) via liquid-solid swelling process. The effect of the co-monomers on the melt grafting of maleic anhydride (MAH) onto PP backbone was studied. Structure and properties of grafts were analyzed using Fourier transform infrared spectroscopy, thermo gravimetric, and water contact angle. At the same time, the mechanism of grafting reaction was discussed. It showed that the grafting ratio of MAH and gel content of grafted products were 2.25 % and 1.56 % respectively when St was used alone. However, when DVB was used alone, these values increased to 3.06 % and 46.31 %, the thermal stability and polarity of grafts were improved in different degrees. Through analyzing the mechanism of grafting reaction, it indicated that the PP macro-radicals were first reacted with the co-monomers, followed by the grafting reaction, thus depressed degradation of PP. DVB possessed two double bonds per molecule, it could be more effective in grafting and coupling between PP macro-radicals.

Key words: maleic anlydride, divinylbenzene, grafting ratio, styrene, polypropylene, co-monomer, melt grafting, gel content