Static electricity in polymers. I. Theory and measurement

Abstract

AbstractA versatile instrument, The Static Propensity Tester, was constructed for the measurement of the rate of electrostatic charge build up and decay on polymer films and fabrics. The tester was used for measuring the rates of both positive and negative potentials in the voltage range of 1000–10,000 volts. From such studies it was observed that above a certain minimum potential, it always took longer for charge to build up on a sample than to decay. Also, the rate of charge decay was found to be dependent on the exposed surface area of a sample as well as its electrical resistance. The loss of charge from a given substance was postulated to occur by two processes, a conduction process through the substrate and a radiation process through the atmosphere. In addition, polymers were found to exhibit a charge selectivity for the sign of the applied voltage, i.e., wool had a faster negative charge decay rate whereas cellulose had a faster positive decay rate. The root‐mean‐square half life of charge decay for positive and negative voltages was found to follow an exponential type law with respect to magnitude of charge and relative humidity. A simple test was devised for characterizing the antistatic behavior of polymers.