AN X-RAY PHOTOELECTRON-SPECTROSCOPY STUDY OF FLAME TREATMENT OF POLYPROPYLENE

X-ray photoelectron spectroscopy (XPS) has been used to study the effects of flame treatment on three propylene polymers, i.e. a homopolymer, an ethylene-propylene copolymer and a rubber-modified polypropylene. Angle-resolved XPS has shown an enrichment in oxygen concentration at the near surface for all three propylene polymers when treated with a mild flame. A depletion in oxygen has been shown at the near surface of the rubber-modified polypropylene treated with an intense flame. The use of simple surface composition models shows that the oxidation depth induced by a mild flame treatment is around 50 angstrom, and that oxygen-containing functional groups may have reoriented or migrated a few angstroms away from the near surface of the rubber-modified polypropylene during the treatment with an intense flame.