Tribocharging of granular polymer as affected by the voltage waveform and frequency of a pretreatment by a dielectric barrier discharge

Triboelectric charges created by friction or contact of several kind of materials are commonly referred to as a source of troubles in most industrial applications, requiring their elimination in most cases. In contrast, the tribocharging of insulating materials is a crucial step for many electrostatic applications involving the electric charges to their proper functioning. Therefore, the acquired charges in this case should be as high as possible to attain the best process performances. The triboelectric charging level depends strongly on the surface state. In this context, the Dielectric Barrier Discharge (DBD), which is non-thermal energetic plasma, is known for its capability to modify surface properties of treated materials and consequently can affect their triboelectric behavior. The purpose of the present work is to study the effect of the DBD electrical parameters on the discharge characteristics and, therefore, the subsequent triboelectric behavior of treated particles of PVC. The carried experiences include the influence of the signal waveform, the applied voltage amplitude and the frequency on the DBD discharge characteristics and the resulting triboelectric charge of PVC particles submitted to the discharge. The DBD-treated particles were charged by triboelectricity in a vibratory device for 5 min. The triboelectric charge acquired by the untreated and DBD-treated particles was measured using a Faraday pail connected to an electrostatic electrometer. The obtained results show that the variation of triboelectric charge acquired by DBD-treated particles depends strongly on the discharge current as well as the discharge distribution in the air gap. The triboelectric charge has been optimally enhanced by about 25% when the square waveform is used with an applied voltage of 27 kV and a 400 Hz frequency.