Adhesion

Improvement of adhesion by plasma

In order to improve adhesion for instance gluing and printing purposes, it is often necessary to selectively increase the surface energy of a solid: in this way, the interactions with the liquids brought in contact with the latter become stronger. Such improvement can be achieved by a surface modification process by means either of a low or atmospheric pressure plasma

An exposure to plasma for few seconds removes external contaminants, breaks the uppermost molecular bonds and makes the treated surface more reactive, resulting in an improvement of the bond strength up to a factor of 30, even for usually inert polymers like polytetrafluoroethylene (PTFE). The process can be tuned by choosing the best suited gaseous feed of the plasma and its operating parameters, and it can be successfully employed even for surfaces with a complex three-dimensional geometry.

Plasma-activated Teflon glued to metal. (c)
Plasma-activated Teflon glued to metal: detachment takes place through the failure of internal cohesion forces in the PTFE (Teflon) piece, instead of the adhesion ones at the metal-polymer interface pair.
Andreas Schulz
Dr.-Ing.

Andreas Schulz

Research associate, Plasma Technology

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