A study of electret properties with vacuum tube electrometer



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It was the purpose of this study (1) to develop a vacuum tube electrometer for rapid determinations of relative characteristics of electrets; (2) to establish the effectiveness of this instrument by verifying an earlier claim that the time required for the reversal of charge on an electret increased with the temperature of the molten mixture components. Electrets were made from Carnauba wax rosin mixtures and the effective surface charge on the electrets measured by means of a vacuum tube electrometer. The method used was the discharge of a capacitor across a high resistance (10[raised 11] ohms) in the grid circuit. Curves were plotted of proportional values of effective charge versus time and the decay characteristics studied. Definite reversal times were obtained for some electrets. The reversal times for other electrets could not be obtained because of the malfunctioning of this type of instrument in relative high humidities. [...]