Atmospheric pressure plasma treatment of polymeric powders

An atmospheric pressure plasma jet is adapted in order to treat polymeric powders. Nitrogen is used as the main operating gas. Ultra high molecular weight polyethylene powder particles are treated in this modified plasma jet reactor. In order to have a reasonable contact time between particles and plasma, the powder is passed 10 times through the reactor. Treated powders are characterized with XPS and some quick tests for the assessment of the wettability of the powder, like a dispersion test in water. After plasma-treatment, about 7 at.% oxygen and 1 at.% nitrogen are incorporated at the particle surface. An improved dispersability of treated PE in water is observed and the treatment is found to be stable in time. The amount of oxygen groups at the particle surface can be increased by adding CO2 in the afterglow of the plasma jet. In order to increase the efficiency of the treatment, the reactor is enlarged and an improved wettability can be achieved by 1 pass through this enlarged system.