DBD modification of polyethylene powder hydrophobicity

Abstract

Problems of the powder particles plasma modification are practically the same as in the case of solid films. Troubles of the powder treatment are related with its threedimensional character, small size of particles, treated large area and problems with powder manipulation, that also must not be neglected. For modification of polymer powder surface properties like wettability and adhesion without changing powder bulk properties there have been mostly applied methods employing low temperature (cold) plasma treatment at low pressures. Presented contribution describes design and investigation of a novel plasma reactor exploiting the dielectric barrier discharge burning in air at atmospheric pressure by ambient temperature and its usability tests. For tests HDPE powder Borealis CB 9155-01 was used. This plasma reactor is of a very simple construction in comparison with other in literature described apparatuses used for this purpose and needs no vacuum equipment. Powder capillarity tests had proved significant powder capillarity changes induced by DBD plasma modification. Modification effect reduction (aging) is remarkably small (max. reduction about 20 % in one year after the modification date), hence modification effect is very time stable.

Plasma treatment of polymer powders – from laboratory research to industrial application

“…The total surface area increases with smaller particle diameter leading to longer processing times. To expose the whole surface of each polymer particle to a plasma various concepts have been explored, including vibration, rotation, conveying, fluidization, and agitation by mechanical stirring (see Figure ) . All concepts have in common that the powders have to be in motion to achieve a uniform plasma treatment.…”

“…(C) Shell type configuration . (D) Rectangular cross‐section with parallel electrodes . (E) Rotating dielectric tube with external electrode bars .…”

“…Plasma‐modified PE powder is often used as raw material for the production of parts using rotational molding technology . There are numerous studies dealing with improved adhesive bonding for powder coating applications on metal surfaces . Parts sintering enables direct painting and adhesive bonding without any additional surface pretreatment .…”

“…Figure illustrates various atmospheric pressure plasma reactor setups designed to treat polymer powders. These include FBRs, CFBRs, batch reactors, barrel reactors, and downer reactors . Table provides the major experimental characteristics (e.g., power, polymer type, gas, treatment time) of the described setups including main experimental results.…”

Remote Plasma Device for Surface Modification at Atmospheric Pressure

“…[5][6][7] Nevertheless, some major problems, such as particle-plasma interactions resulting in enhanced depositions and inhomogeneous surface treatment in filamentary discharges, have not been solved yet. Furthermore, powder conveying without elaborate dispersion systems additionally endanger homogeneous particles treatment due to agglomeration and the formation of clusters.…”