Morphological and chemical analysis of PP film treated by Dielectric Barrier Discharge

PP films have been activated by DBD, with different gases (air, N2, H2, CO2) and at different energy treatments. Then film surfaces were analysed by AFM, contact-angle technique, ink test measurements and XPS, to explore modifications in surface topography, wettability, and oxidation state. After the treatments, it is possible to observe the formation of water-soluble low-molecular-weight oxidized materials (LMWOMs), which dimensions and spatial density are related to treatment parameters. Using AFM data it is possible to analyse the statistical distribution of the bubbles sizes. The analysis of XPS spectra shows the formation of oxidized polar groups on surface (e.g. C-O, C=O, COH) and allows to evaluate the extent and the nature of film oxidation, and how it influences surfaces properties. The relationship between surface chemical and morphological modifications and treatment parameters is pointed out. Then PP sample have been monitored in the time, to determine the ageing effects.