Structure and rheology of different polypropylene architectures prepared by co-agent assisted radical processing

The grafting of polar monomers to polyolefin backbones carried out in the melt in the presence of peroxides is accompanied by a restructuring of the pristinemacromolecule architecture depending on reaction conditions and original polyolefin structure. In the case of polypropylene (PP), side reactions, mainly degradation, are often controlled by the use of coagents which also provide amore complex scenario as far as possible reactions and final polymer structure are concerned.We have demonstrated that 2-furyl acrylates are very active inmaintaining the highmolecular weight of PP during various functionalization processes carried out in the melt in the presence of peroxides. In the study reported here, PP samplesmodified in themelt by free radical processes initiated with peroxides in the presence of butyl-3-(2-furyl) propenoate and its mixture with maleic anhydride were examined, and the effect of structural changes achieved were related to the rheology of themelt and morphological behaviour under heating. Rheological analysis is consistent with the formation of long branchedmacromolecules to an increasing extent with increasing content of reagents with respect to the polyolefin. Differential scanning calorimetry shows that the amount of long-chain branching is responsible for a decreaseof themelting temperatureandanincreaseof thecrystallization temperature. These results confirm that the functionalization coagent andmonomer can give large macromolecule structure changes which can be driven in different directions depending on feed composition