Erosion of polymers in atmospheric pressure plasmas
Mechanisms and influencing factors
Authors: Dariusz Korzec und Markus Trabold
Date: 2024
First published at: https://www.isgatec.com/artikel/erosion-der-polymere-in-atmospharendruck-plasmen/38911
Cold atmospheric pressure plasmas (ADP) are widely used for the conditioning of polymer surfaces. The main application in industry is to increase the free surface energy, which leads to better wettability with liquids and stronger adhesion of coatings, adhesives and potting compounds. A very short treatment time is typically sufficient to achieve such a modification of the polymer surface. Depending on the type of ADP, this ranges from a few 10 ms to a few seconds. A longer interaction between ADP and a polymer surface leads to further changes in the material properties. One of these changes, which becomes noticeable after hours, days or weeks, is erosion of polymers.
ADP is an generic term that covers numerous methods of plasma generation. Polymer surfaces can be exposed to a direct or indirect plasma. A remote or indirect plasma is characterised by a high concentration of chemically reactive species without strong luminescent effects and electrical charge. The main chemical species in an indirect air plasma include, for example, ozone and other RONS (reactive oxygen and nitrogen species). A direct plasma has a significant concentration of charged particles (electrons and ions) and excited particles. The latter cause the plasma to glow.
Conclusion
The polymers are subject to erosion in the oxygen-containing ADP. The rate of erosion depends on the type of polymer and the plasma, among other factors. Temperature plays an important role here. Erosion can lead to an undesirable impairment of the polymer properties, but it can also be utilised technologically for the targeted decomposition of the polymer material.
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