Life time of thermal electrets of carnauba wax, esters, fatty acids and alcohols

Residual surface charge with time was observed with thermal electrets of carnauba wax, esters extracted from carnauba wax, fatty acids and alcohols derived by hydrolysis of esters. All the electrets were prepared in 1951-1953. The samples were poled by applying various electric fields in the temperature range between room temperature and 65°C. After poling, both surfaces of the electrets were shorted with tin foil and kept in a desiccator. Thirty-six years have passed after the preparation of the electrets; a stable homocharge of (4.6~6.6)×10^-5 C/m² was observed for electrets of carnauba wax, esters, and fatty acids, but no charge was observed for fatty alcohols