Effects of plasma treatment of surfaces of charge storage in polypropylene

On the surfaces of polypropylene samples treated in an 800-kHz plasma of air at low temperatures, the level of charge storage is increased. This charge storage is found to depend strongly on the plasma treatment and charge injection conditions. Under optimal conditions, polypropylene with plasma treatment can store about 50% on average more charge. The thermally stimulated charge decay becomes much slower than for samples without treatment. Infrared absorption and photoconductivity spectra indicate that the plasma treatment enhances the formation of C=O and C=C bonds and the degree of crystallinity, which results in an increase of polar groups and deep traps