Surface modification of polypropylene film using dielectric barrier corona discharge

The impregnating property of polypropylene (PP) film is one of the major topics for all-film power capacitors. To improve the impregnating property of PP films, we studied the surface modification of PP films using dielectric barrier corona discharge (DBCD) in atmospheric pressure. Firstly, we developed a low-temperature plasma generator based on the DBCD mechanism and studied its discharge characteristics. Then, we modified some PP films using the generator, and analyzed the modification effect of the PP films in the aspects of chemical components, microstructures, and hydrophilic property before and after the modification. The results show that, after the plasma treatment, a large amount of oxygen-containing groups are introduced into the surfaces of the PP films. On the treated surface, the surface oxygen content increases to 10%, the contact angle decreases by 30%, and both the surface roughness and impregnating properties are enhanced. Meanwhile, the electrochemical feature of the PP film surface also changes: the AC breakdown voltage of treated PP film is increased by 12%.