ABSTRACT
Modification reactions in extruders involve reactions between a molten polymer and one or more monomeric species. The reaction is generally initiated by peroxide that creates an active site on the polymer or monomer. Depending on the type of monomer used, the peroxide concentration, the temperature, and the mixing in the extruder the length of the grafts may vary between a single molecule and a true graft copolymer. Depending on the reactivities the grafting reaction may have to compete with homopolymerization. Especially when the homopolymerization is suffciently fast, good mixing is absolutely necessary to create a high intersurface area, maximizing the grafting reaction. Many grafting reactions can be considered as multicomponent reactions that are diffusion limited. Good mixing is indispensable for the product quality, because otherwise homopolymerization of the monomer and crosslinking or chain scission of the polymer can occur.
