Treatment of a polyethylene powder using a Remote Nitrogen Plasma reactor coupled with a fluidized bed: Influence on wettability and flowability

The industrial use of polymers is increasing, but taking into account their low surface energy, a modification of their surface properties is often required. A Far Cold Remote Nitrogen Plasma is used both to fluidize and to treat a polyethylene powder in order to increase its hydrophilic character. The evolution of the wettability of the powder as well as the one of its physical (density, particles size distribution, average diameter, shape factor, and BET surface area) and flow properties (angle of repose, angle of slide, and Hausner index) are determined versus various experimental conditions. It is shown that the plasma treatment efficiency is strongly dependant on the oxygen content of the nitrogen flow and on the velocity of fluidizing gas. Best wettability is obtained by the addition of 0.75% of O2 in the nitrogen plasma gas and with a high gas velocity. It is also evidenced that the flowability of the powder is slightly altered by the plasma treatment.