Comparison of rheological behavior of branched polypropylene prepared by chemical modification and electron beam irradiation under air and N2

Chemical and electron beam irradiation methods were used to introduce a branched structure into polypropylene and propylene–ethylene copolymer. The chemical method was carried out in an internal mixer using initiator and TMPTMA monomer. In irradiation method, the polymer was irradiated by electron beam under air and nitrogen atmosphere. The branched structure in the modified polymer was confirmed by rheological measurements. While degradation was significant in chemical method, branching occurred efficiently by irradiation under air. Small amount of ethylene in the propylene copolymer promoted branching over degradation.