STUDY OF FAST PROCESSES IN OXIDIZED POLYPROPYLENE IN THE PRESENCE OF PYRENE

The study of oxidized polypropylene, undoped and doped with pyrene was carried out with the main aim of investigating energy and charge tran sfer in these systems. The transient absorption spectrum of trapped el ectrons was not detected in the case of oxidized polypropylene because of electron scavenging by products of polymer oxidation (peroxides an d carbonyl groups). In doped oxidized polypropylene, transient absorpt ion bands due to pyrene radical anions (lambda(max) = 500 nm) and cati ons (lambda(max) = 450 nm) were observed. The yields of these bands in this system were lower than in non-oxidized polypropylene. The ratio of absorption at 450 nm and 500 nm was different in these polymer matr ices, too. Relatively less pyrene radical-anions were generated in oxi dized system. The pulse irradiated pyrene-oxidized polypropylene syste m generated much weaker emission attributed to pyrene monomer fluoresc ence than in non-oxidized polymer. All these results suggested that ox idized polypropylene matrix interacted with primary charges hence, pyr ene radical ions yield and solute ion-recombination leading to excited state formation was limited. (C) 1998 Elsevier Science S.A.