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Effect of High Voltage Switching Frequency on DBD Plasma in Air for PET Surface Modification

This paper studied on the laboratory scale of DBD plasma source of atmospheric air pressure that drove by ac square wave full bridge inverter. The electric parameters were investigated such as applied high voltage, current, and switching frequency. In the gap space 2 mm, the uniform glow discharge plasma can produce with the sinusoidal high voltage 11 kV and discharge current about 10 mA on the switching frequency range of 4–6 kHz. Furthermore, the thermal camera shown that the temperature of plasma was about 38°C. This homogeneous glow discharge plasma had used for surface treatment of thin PET film 100-micron at different exposure times. The water contact angles of PET surface reduced to 32° when treatment time was 45 s. However, the bulk properties of untreated and treated PET film were quite similar.