Electret properties of cycloolefin copolymers

Abstract

The electret properties of cycloolefin copolymer (COC) films, metalized on one side and charged with corona or electron-beam methods, were investigated. Measurements of the isothermal decay of surface and bulk charges under room conditions and at elevated temperatures and humidities as well as thermally-stimulated current measurements indicate excellent stability of surface charges of positive and negative polarity. Negative bulk charges, injected be electron beams, are less stable. The COC materials are nonpolar and show no measurable piezo- and pyroelectric activity.