Adhesion behaviour of polypropylenes after flame treatment determined by XPS(ESCA) spectral analysis

In a number of automotive applications of polypropylene (PP) good paint adh esion is essential. For industrial applications, the initially poor adhesio n properties of PP compounds are often improved by flame treatment, resulti ng in good paint adhesion on the PP parts. For control purposes, intensive and time consuming paint tests are required. To relate adhesion behaviour w ith the parameters used in the flame treatment modification, several method s are applied such as simple surface tension tests with inks (wetting tests ), contact angle measurements and standard XPS(ESCA) measurements. Unfortun ately a good correlation is rarely obtained between these tests and the des ired adhesion behaviour under rigid test conditions. Good wetting, for exam ple, is necessary, but is no guarantee for good adhesion. In this paper res ults are presented on the characterisation of flame treated PP compounds by XPS, as well as the predictive information obtained from the XPS study con cerning the paint adhesion behaviour of the modified PP surfaces. (C) 2001 Elsevier Science B.V. All rights reserved.