Surface studies of polyethylene modified by flame treatment

Effects of flame treatment on polyethylene (PE) surfaces have been studied using contact-angle measurements, attenuated total reflection infrared spectroscopy (ATR-IR), X-ray photoelectron spectroscopy (XPS), and an adhesion test. A significantly higher level of surface oxidation was induced by flame treatment on PE than on polypropylene (PP) under a given set of conditions, and unlike the case of PP the oxidation of PE is not confined to the XPS sampling depth on the polymer surface even for a mild flame treatment. High-energy resolution XPS has revealed several different functionalities on the surface and ATR-FTIR has clearly detected the peak at 1715 cm-1 which can be attributed to C=O groups. Large contact-angle hysteresis was obtained and was attributed to chemical heterogeneity on the surface. Good adhesion with an epoxy adhesive has been obtained after flame treatment.