Effect of physical dimension of cavities on charging behavior and time-temperature stability of a new family of polymeric cellular electrets

Cellular polymers obtained from cyclo-olefin copolymer (COC) become electrets upon charging under high levels of electric field. Investigation of charging mechanisms is fundamental to reach optimization of electret and piezoelectric properties. This paper presents results and considerations relevant to the charging process of such materials and its dependence on partial discharges occurring in their cavities, as well as to time and temperature stability of electret properties. In particular, the effect of physical dimension of cavities on the charge process was investigated, focusing on the dependence on the stretching strength applied during the manufacturing process and the expansion rate.