PLASMA POLYMERIZATION AND SURFACE-TREATMENT OF POLYMERS

In this article surface treatment of polymers by both surface modification and plasma polymerization has been discussed. A low pressure 70 kHz discharge with corona configuration of electrodes (H.V. hollow blade - grounded cylinder) has been employed in order to simulate the industrial surface treatment of polymers. In the case of non polymerizing plasmas such as N2 the modifications created on the surface of a polymer such as polypropylene (PP) have shown to be the cleaning effect, crosslinking polymer fragmentation, oxidation and nitrogen incorporation for very short treatment times (100 ms - 7 s). These effects lead to an increase of the wettability, the surface conductivity and the adhesive properties of the PP films. Indeed the latter has been detected by a study of the PP-Al interface by AES and the measure of the peel-strength. In the case of the polymerizing system such as CF4 + H2 mixtures, the role of the gas composition and the polymer substrate structure have been pointed out on the growth mechanisms and the structure of the deposited polymer. By varying the hydrogen percentage in this mixture a wide range of surface energies (from non wettable to wettable surfaces) has been obtained.