Comparison of the UV-degradation chemistry of unstabilized and HALS-stabilized polyethylene and polypropylene

The UV-degradation of unstabilized and HALS-stabilized polyethylene (PE) and polypropylene (PP) is described. The degradations are characterized by measuring the oxygen uptake, the formation of CO and CO2, the FT-IR spectra, the mechanical properties and the oxygen content of the films. The oxygen uptake of the unstabilized polymers led to the expected changes in the IR-spectra and embrittlement of the films, while oxygen uptake by the HALS-stabilized PE and PP caused only minor changes. The results are explained assuming that the initiation of the photodegradation of PP and PE is due to charge transfer complexes. (C) 1996 Elsevier Science Limited