A Bidirectional Acid-Base Charging Model for Triboelectrification: Experimental Verification by Inverse Gas Chromatography and Xerographic Charging of Toner and Carrier

Abstract

Inverse Gas Chromatography (IGC) has been applied to study surface acid and base properties of xerographic developer materials. The data is interpreted using the recently proposed surface states bidirectional charge transfer model. In that model, charge exchange occurs between Lewis acid and basic surface states on both surfaces in both directions, with the net charge on a material the result of the sum of the charge transfer in both directions. In previous work, model carrier and toners were prepared, blending the toner particles with nano-particulate metal oxide surface additives. It was shown that the IGC Ka and Kb, the Lewis acid and Lewis base parameters, within the bidirectional charge model, fit very well the charge on the surface additives in these model toners. The current study extends that previous work, by measuring the IGC parameters, as well as xerographic charging, for a series of “real”, rather than model toners, without surface additives. The complete set of toners was studied with two different carriers to form a triboelectric series that is consistent with the bidirectional acid-base charge transfer model. The magnitude and the sign of the charge exchanged between the toner surface and the carrier is determined by the relative surface Ka/Kb acid/base parameters for the toner and carrier surfaces. For toner surfaces with Ka/Kb greater than that of the carrier surface, predicted and observed toner charge is negative; while for toner surfaces with Ka/Kb less than that of the carrier surface, the predicted and observed toner charge is positive. It is further shown that the Ka/Kb parameters can be interpreted as defining work functions for these toner and carriers.