Mechanism and kinetics of polyethylene crosslinking by α,α′‐bis(tert‐butylperoxy)‐p‐diisopropylbenzene

The study of the mechanism of polyethylene crosslinking is realized by a kinetic analysis of the α,α‐bis(tert‐butylperoxy)‐p‐diisopropylbenzene decomposition, as well as by the determination of its decomposition products and crosslink formation in the polymer. The experiments were carried out in a temperature range of 118°–148°C in both polyethylene and its low‐molecular model, n‐octane. From the results obtained it follows that the peroxide decomposition in both hydrocarbon media is kinetically a unimolecular reaction with an activation energy of 36 ± 2 kcal/mole and with an equivalent participation of both peroxidic groups, whereby a biradical formation is improbable. Macroradicals arise by a dehydrogenization reaction in which mainly primary oxyradicals of various types take part and methyl radicals are also formed by a transformation process of the former. Both types of radicals decay exclusively in a substitution reaction with polymer chains. The whole process is terminated by macroradical recombination so leading to crosslink formation in polyethylene.