Abstract:The surface of a polyamide-12 (PA-12) foil was modified in order to improve the adhesive properties by two types of atmospheric pressure plasma sources. The samples were characterized using contact angle measurement, adhesive properties measurement and X-ray photoelectron spectroscopy (XPS). The ageing of the plasma modification was also studied. A significant increase in wettability was observed at different treatment times. The same effect was also seen in the adhesive properties -the adhesion was increased almost 12 times for 10 s DCSBD treatment in comparison to untreated PA-12. XPS analysis confirmed chemical changes due to the plasma modification of the PA-12. It was concluded that both plasma sources improve the adhesive properties of PA-12, with DCSBD obtaining better results.

Diffuse Coplanar Surface Barrier Discharge (DCSBD) is a novel type of atmospheric-pressure plasma source developed for high-speed large-area surface plasma treatments. The statistical behavior of microdischarges of DCSBD generated in artificial air atmosphere was studied using time-correlated optical and electrical measurements. Changes in behavior of microdischarges are shown for various electrode gap widths and input voltage amplitudes. They are discussed in the light of correlation of the number of microdischarges and the number of unique microdischarges' paths per discharge event.The 'memory effect' was observed in the behavior of microdischarges and it manifests itself in a significant number of microdischarges reusing the path of microdischarges from previous half-period. Surprisingly this phenomenon was observed even for microdischarges of the same half-period of the discharge, where mechanisms other than charge deposition have to be involved. The phenomenon of discharge paths reuse is most pronounced for wide electrode gap width and/or increased input voltage amplitude.