Application of microwave discharges for treatment of polymer surfaces

In this paper we analyze application of a simple microwave cavity discharge on the surface modification of polymers. Electrons and radicals from the low pressure plasma as well as the metastable excited oxygen species react intensively with many engineering plastic materials leading to the increased adhesion of polymers. This is of importance to achieve better bondability by gluing, painting, varnishing, stamping, printing or metalizing. The change of the wetting contact angle is discussed with respect to the treatment time and the polymer used. The creation of reactive functional groups of the hydroxyl and carboxyl acid type on the polymer surface is mainly responsible for the better adhesion. The lifetime of the bondability of polycarbonate, polymethyl methacrylate and polyether ketone was investigated. The surface modification of plastic materials may be performed in the vacuum chambers operated by low cost standar d microwave oven components or at a higher expense by rf generators at 13.6 MHz.