THE OXIDATIVE-DEGRADATION OF HETEROPHASIC ETHYLENE-PROPYLENE COPOLYMERS - A COMPARISON OF PHOTOPRODUCT FORMATION UNDER NATURAL AND ACCELERATED CONDITIONS

The natural weathering behaviour of various heterophasic ethylene-prop ylene (E-P) copolymers and their fractions was studied. The results ar e compared with those for polypropylene homopolymer (PP). The extent o f natural weathering was monitored by Fourier transform infrared spect roscopy. Also, the photo-oxidation behaviour of isotactic PP, heteroph asic E-P copolymers and their fractions under natural exposure were co mpared with corresponding photoirradiated samples. The photoproducts a re produced in the same relative proportions under accelerated and nat ural exposure, which shows that the mechanisms by which they are forme d are not related to the temperature and the photon flux.