Vacuum-ultraviolet photolysis of polymers

Polyethylene (PE), polypropylene (PP), and poly(ethylene terephthalate) (polyester, PET) were subjected to vacuum-ultraviolet (VUV) radiation from a hydrogen plasma in high vacuum at 10(-8) mbar. The residual gas was analysed by mass spectrometry. PE and PP were found to produce high amounts of hydrogen during irradiation. They also formed considerable-amounts of hydrocarbons. PP split off its methyl side-group in particular during the first few seconds of irradiation. The species found in the residual gas indicate the formation of double bonds, cross-links and main chain scissions in the polymer surface. PET appeared to be quite stable under VUV irradiation. The only species that was found in the gas phase in significant amounts was carbon dioxide, which came from the destruction of the ester groups. (C) 1998 Elsevier Science S.A.