Interaction between plasma jet and silicone rubber covered by porous inorganic contaminants: Surface hydrophobicity or hydrophilicity?

Abstract

The variation of surface hydrophobicity of silicone rubber materials covered with porous inorganic pollution layer under the action of atmospheric pressure plasma jet presents some new features, which have important engineering applications in the field of outdoor insulation of power systems. Interaction of the plasma with the polluted silicone rubber is studied and surface hydrophobicity is measured. Experimental results show that the exposure of plasma greatly accelerates the transfer of low molecular weight siloxanes (LMWs) in the pollution layer. However, the surface hydrophobicity is determined by the LMWs contents and the exposure time. Two acceleration effects of plasma during and after plasma exposure are proposed, their influence on surface hydrophobicity is analysed and related mechanisms are clarified. In addition, the competing influence of plasma-induced acceleration of the transfer of LMWs towards the surface and plasma-oxidation of LMWs on surface hydrophobicity is discussed.