ESR MOLECULAR-DYNAMICS STUDY AT THE OXIDATION SITES OF POLYPROPYLENE WITH NITROXYL SPIN LABELS AND SPIN PROBES

Novel methods suitable for the selective insertion of nitroxyl spin la bels and spin probes at the oxidation sites of isotactic polypropylene have been developed based on reactions with the oxidation products, o n spin trapping with nitroso and nitrone compounds and taking advantag e of the spontaneous generation of nitroxyl radicals as intermediates in the stabilization mechanism by the HALS. The analysis of the esr sp ectra of the doxyl spin label and of the spin probes from the HALS, pe rformed according to the stochastic Liouville theory, has allowed info rmation to be obtained on the molecular mobility at the oxidation sire s as a function of the temperature.