Thermally and UV initiated degradation of polypropylene in the presence of 2,5 bis(2-furylmethylene) cyclopentanone and heterogeneous distribution of hydroperoxides assessed by non-isothermal chemiluminescence in nitrogen

Abstract

Abstract 2,5 bis(2-furylmethylene) cyclopentanone (F 2 C) has been shown to be a good inhibitor of thermal oxidation of polypropylene (PP). F 2 C structure, namely of cyclopentanone moiety linking two furan rings via conjugated system of double bonds performs captodative properties towards free radicals that may be the potential reason of its thermo-oxidation stabilization effect on polypropylene. When F 2 C is UV irradiated it acts as a weak photo-sensitizer probably due to carbonyl group in cyclopentanone, however, the original structure of F 2 C is converted fast to the products losing photo-sensitizing effect but still keeping some residual antioxidant effect on thermal oxidation of polypropylene that is probably due to 335 nm UV band. The changes of non-isothermal chemiluminescence runs in nitrogen and in oxygen and development of FTIR spectra for 0.3% of F 2 C in polypropylene were compared with pure polypropylene and polypropylene containing 0.3 wt. % of Irganox 1010. New observation has been presented namely that non-isothermal chemiluminescence runs in nitrogen shows the peak around 145 °C attributed to the decomposition of hydroperoxides superimposed with an additional peak appearing around the temperature of melting of polypropylene crystallites. This appears to be brought about by accelerated decomposition of hydroperoxides due to their higher concentration in heterogenous zones formed in the previous oxidation and to their increased mobility when polymer melts.