AbstractIsotactic polypropylene of various degrees of crosslinking was prepared using high concentrations of dicumyl peroxide as the crosslinking agent. Free radicals were generated by γ irradiation of crosslinked iso‐PP with a dose of 2.4 Mrad. It was found that the rate constant for free‐radical decay is independent of crosslinking in the temperature range from −30 to +20°C. The result is discussed from the point of view of degradation processes taking place simultaneously with crosslinking of