SURFACE MODIFICATION OF POLYETHYLENE AND MAGNETITE POWDERS BY COMBINATION OF FLUIDIZATION AND PLASMA POLYMERIZATION

A new surface modification process of powders was attempted, using the combination of fluidization and plasma polymerization techniques. This study shows that the combination of the fluidization and plasma polymerization techniques is useful in the surface modification of powders. Polyethylene and magnetite powders were first fluidized, and then were modified in the fluidization state by the plasma polymers of tetrafluoroethylene (TFE). XPS spectra of the modified powders showed that the surfaces of the polyethylene and magnetite powders were coated with fluorine-containing polymers, and that the polymers were mainly composed of CH, CF, and CF2 groups. The elemental composition (F/C atomic ratio) and the composition of the fluorinated carbons in the plasma polymers were dependent on the W/FM parameter, as well as the TFE concentration in the TFE/Ar mixture. It is emphasized that the W/FM parameter is a factor used to control the chemistry of the plasma polymerization reactions. The triboelectric charge of the magnetite powders, when modified by the plasma polymerization of the TFE/Ar mixtures, was higher than the unmodified by about two. The static electrification properties of the powders can changed by the plasma-polymer coating.