One of the most common applications of cold plasma is the activation of polyolefines, such as polypropylene (PP) prior to an adhesive process.
Surface activation (or plasma activation) is a method of surface modification with plasma treatment, in order to improve surface adhesion properties of many materials like metals, glass, ceramics, a broad range of polymers and textiles and even natural materials. It is widely used in industrial processes to prepare surfaces for bonding, gluing, varnishing and painting. Plasma treatment achieves this effect through a combination of reduction of metal oxides, ultra-fine surface cleaning from organic contaminants, modification of the surface topography and deposition of functional chemical groups.
Plastics are usually characterized by inert surfaces with surface energies between 20 and 40 mN/m. In order to wet a surface, however, the surface energy of the polymer must exceed the one of the paint or the adhesive. This condition can be achieved through a plasma treatment of the surface and is called “activation“ in plasma technology.