Behavior of water droplet on electrically stressed polymeric coating surface

This paper describes the behavior of water droplets on an electrically stressed polymer surface and their influence on the surface charge distribution. Tests were done by placing water droplets on the surface of the silicone rubber (SR) and ethylene vinyl acetate (EVA) copolymer sheets with a micropipette, and their behaviors were observed by a high-speed video camera after ac voltage was applied. It was demonstrated that the droplet deformed and vibrated due to the electrostatic force, which caused the droplet to be charged negatively before flashover. However, when a corona discharge occurred at the tip of the droplet where a locally high electric field was built, the charge on the droplet gradually changed to positive with the increase of applied voltage. In addition, the above-mentioned characteristics are different between SR and EVA because of their different surface conditions.