Corona Polarization Effects on Polymer Surfaces
Corona polarization in air is an usual method for depositing and injecting charges in polymers for production of electrets. The charges remain either on the surface or near it We have studied the effect of the polarization atmosphere, the polarization current and the time of polarization on the stability of the electrical charge of the electrets. For these studies we have used the technique of Thermally Stimulated Currents (TSC) that gives depolarization currents due to the jumping of the charges from traps, when the sample is heated up at a constant rate.
For polymers (Teflon-FEP) polarization in air for a very short time and small corona currents the TSC measurements present a single peak, denoting the existence of one level of energy traps. For longer times and/or higher corona currents new peaks appear indicating the formation of new traps. Polarizations in O2, CO2 and dry air atmosphere, show also modifications on the initial trap distribution, while polarization in N2 atmosphere does not modify the initial single level energy trap.
We interpreted the results considering that the corona discharge can produce charged particles as well as neutral excited molecules. The interaction of these excited molecules with the polymer surface produce new traps, that can be filled up by the incoming charges, as happens for the preexisting traps of the polymer surface.
KeywordsPolymer Surface Corona Discharge Thermal Stimulate Discharge Current Shallow Trap Corona Current
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