On the carnauba wax eiectret

摘要

A systematic study has been made of the permanent surface charges, which can be produced on discs of carnauba wax and lead to the formation of the electret. Different electrical and thermal treatments have been used-A complete experimental cycle included a) application of the polarizing voltage concomitant with thermal treatment, b) period of short-circuit at room temperature, and c) reheating, The current J(t) in the external circuit and the charge q(t) of one of the electrodes of the capacitor containing the sample were measured during the application of the polarizing field and after withdrawal of the field and short-circuiting. The charge of the electrode was measured with the aid of an improved dissectible capacitor (Fig. 1); the capacitor was placed inside a desiccator, humidity being lower than 5%. Never during one cycle was the sample removed from the capacitor; thus uncontrolled handling of the sample was avoided and the problem reduced to its proper terms, i.e., the realization of quantitative measurements of the external current and of the charge of the electrodes of a capacitor containing a solid dielectric.