In the melt-grafting PP system

the addition of appropriate comonomer could significantly enhance the grafting levels of the grafting monomers and reduce the extent of scission of PP backbone.The criterion of selecting of the appropriate comonomer in PP radical grafting system was discussed. Monomers with different Q and e values were grafted on PP and the Q-e scheme was applied to describe the elationship between those monomers and the comonomer styrene.It was found that the comonomer worked only when the following two conditions were satisfied:The reactivity of the comononer towards PPmacro-radicals mustbe greater than that of the grafting monomer;the Q value of comonomer must be close to that of the grafting monomer. The grafting reaction will be restrained if the Q values between the comonomer and the grafting monomer are greatly different.