Estimation of chain scission during vulcanization. Part III. Temperature effects in the peroxide vulcanization of natural rubber

The vulcanization of unextracted natural rubber by dicumyl peroxide is less efficient at 100–110°C. than at 140–160°C. Sol-gel data are presented which suggest that this is not the result of the presence of a temperature-dependent scission process. It is more likely that there is competition between the rubber hydrocarbon component of the natural rubber and the various nonrubbers also present for the cumyloxy and methyl radicals derived from the dicumyl peroxide and that the balance of this competition is temperature-dependent.