Possible protonic conduction in Teflon FEP under humid atmospheres

Abstract

Studies of constant current corona. negatively charged Teflon FEP samples, show a surface potential build up depending on the humidity content. In dry air atmosphieres it is possible to charge a sample to very high charge densities. In humid atmospheres the surface potential saturates at lower potentials. Charge centroid position measurements show that in samples charged under humid conditions the centroid position is deeper than in the case of dry conditions. On the other hand, surface charge decays much faster in humid atmospheres than in dry air. These results are explained in terms of a protonic model for charge transport, in Teflon FEP under humid conditions, in which the negative surface charges induce a drift of ions from the bulk to the surface charge layer.