Plasma afterglow treatment of polymer powders: Process parameters, wettability improvement, and aging effects

Polyethylene powder is treated in an atmospheric pressure circulating fluidized bed plasma reactor, in which powder particles pass the afterglow of 64 discharge channels multiple times. Contact angle drops with increasing treatment time and powder gradually becomes wettable with liquids of higher surface tensions. X‐ray photoelectron spectroscopy is used to prove particle surface functionalization induced by the afterglow process. Two different channel arrangements and geometries are studied and the influence of applied voltage and frequency on activation efficiency is investigated. Minimal surface aging is observed when samples are stored in air. However, when dispersed in water, particles maintain the engineered wettability. Polymer powder is activated in the afterglow of 64 dielectric barrier discharges. With increasing treatment time powders gradually become wettable with liquids of higher surface tensions and XPS measurements confirm oxygen incorporation onto particle surface. Influence of reactor geometry, applied voltage and frequency as well as storage time on measured powder contact angles is discussed.