Spin labelling of degraded polypropylene. Part I. Formation of oxazolidine nitroxide

Abstract The kinetics of nitroxide formation on a polypropylene (PP) chain by reaction between carbonyl groups of γ-irradiated PP and 2-amino-2-methyl-1-propanol has been studied. During the reaction the total concentration of carbonyl and amine groups passes through a maximum. At the end of the reaction a weak ESR signal due to nitroxide groups was detected and its intensity was strongly enhanced by peroxidation with m -chloroperbenzoic acid. The presence of nitroxides after the reaction with the aminoalcohol has been explained by the interaction of an oxazolidine moiety with singlet oxygen coming from the decomposition of PP-hydroperoxides or by reaction of the latter compounds with the oxazolidine nucleus.