Surface modification of polyethylene powder using plasma reactor with fluidized bed

The fluidization technique was applied for the surface modification of powder by plasma, and whether the technique was a practically useful one in the surface modification of powder or not was discussed. Polyethylene powder was used as a specimen to be modified. The oxygen plasma treatment of the polyethylene powder in the fluidized state showed a capability that the surface of the powder was changed from hydrophobic to hydrophilic. The contact angle of water for the treated powder surface was 51°C, which was estimated from the dynamic wicking data. The hydrophilic surface modification of the polyethylene powders in the fluidized bed required the operation of the plasma treatment for at least 3 h. The requirement of the plasma operation for long time rises mainly from large surface area of the powder. The oxygen plasma treatment led to the formation of oxygen functionalities including C O and C(O)O groups at the outermost layer of the powder. The concentration of the CO and C(O)O functionalities reached 10 and 6% of the total carbon elements being in the XPS sampling depth, respectively. From these results we conclude that the fluidization technique is a useful manner in the surface modification of powder by plasma.