These differences in mechanical properties must be attributed to influences of peroxide type and PP degradation. DCP and DTBPIB have typical crosslinking temperatures close to the mixing temperature, high crosslink efficiency and provide highly reactive radicals as discussed in 3.1, so they can easily provide a high amount of crosslinking in the rubber molecules. Moreover, in spite of the decreasing viscosity of PP via PP degradation, the blends with DCP or DTBPIB still give superior overall mechanical properties relative to the case of using DTBPH or DTBPHY as curatives.