On the effect of functionalizer chain length and water content in polyethylene/silica nanocomposites: Part II — Charge transport

The effects of functionalizer chain length and water content were explored in a series of polyethylene/silica nanocomposites. Silane molecules with differing chain lengths (propyl, octyl and octadecyl) were used to vary the nanoparticle surface chemistry, while vacuum drying and water immersion were used to extract water from or add water to samples previously equilibrated under ambient conditions. Electrical conductivity was found to be highly dependent upon water content as were the space charge distributions. Both interfacial conditions and the overall charge transport through the sample were strongly dependent on absorbed water and, as such, were found to vary with time through exchange of water with the sample's environment. Changes to charge transport dynamics due to the functionalizer chain length were, however, subtle. The removal of surface hydroxyl groups appears to be the primary mechanism by which functionalization influences electrical behavior; this reduces water uptake and, as a consequence, modifies charge transport behavior.