Homocharge

Abstract

Residual surface charge with time was observed for 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 A.D.1951-1953. The samples was poled by applying various electric field at temperature range between room temperature and 65°C. After poling, both surfaces of the electrets was 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) x I0 SC/m2 was observed for electrets of carnauba wax, esters and fatty acids, but no charge was observed for fatty alcohols.

Introduction

About seventy years have passed since the electret was discovered by Eguchi. He prepared the original electret from a mixture of equal volumes of carnauba wax and rosin, which was poled under a high static electric field above its melting point and cooled down to room temperature under the field. So far, the electret property of carnauba wax was fully investigated. However the electret property of esters, fatty acids and fatty alcohols extracted from carnauba wax were investigated very few. This paper presents some experimental results on life time of thermal electrets made from carnauba wax, esters, fatty acids and fatty alcohols. All the electrets were prepared in A.D.1951 1953.