Modification of PMMA surface hydrophobic properties using an atmospheric-pressure plasma jet array for the enhancement of flashover voltage

The surface insulation performance of insulating materials is crucial for the electrical equipment safe operation and power system stable operation. The improvement of the surface hydrophobicity of insulating materials is important to improve surface flashover voltage. In this paper, an Ar/hexamethyl disiloxane (HMDSO) atmospheric-pressure plasma jet array is constructed to improve the surface hydrophobicity and insulation performance of polymethyl methacrylate (PMMA). With the discharge characteristics and water contact angle (WCA) measurements at different HMDSO contents and treatment times, the surface hydrophobicity of PMMA can be improved significantly and the maximum WCA value can reach about 153°, which meets the standard of super-hydrophobic surface and be benefit of free pollution and moisture. The physical and chemical changes in the treated PMMA surface at the optimal treatment conditions (60 s treatment time and 0.08% HMDSO content) and the untreated PMMA surface are investigated by atomic force microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. It is found that the treated PMMA surface is covered with the dense nanoscale film and silicon containing hydrophobic groups. The corona onset, dry and wet flashover voltages of the PMMA surface before and after jet array treatment are compared. It is found that the corona onset voltage is increased from 10.0 to 13.8 kV, the dry flashover voltage is increased from 15.1 to 19.2 kV, and the wet flashover voltage is increased from 8.2 to 12.4 kV. The mechanisms of the enhancement of the surface insulation performance of insulating materials and the surface hydrophobic modification are discussed. Graphic abstract: [Figure not available: see fulltext.]