Influence of the geometrical parameters of a dielectric barrier discharge reactor on the subsequent tribocharging of granular polymers

Tribocharging of insulating materials is a pivotal step in several electrostatic applications in which the charge value has an important consequence on the outcome of the process. The Dielectric Barrier Discharge (DBD) at atmospheric pressure is an excellent energetic plasma source having the aptitude to change surface properties and, thereby, to enhance triboelectric charging of granular insulating materials. This paper aimed to investigate the influence of dielectric barrier geometrical parameters on the triboelectric charge of the DBD-treated Polypropylene (PP) and Polyvinyl Chloride (PVC) mm-size granules. The studied parameters include the air gap between the upper barrier and the surface of the granular layer, the number of granular layers, as well as the material forming the dielectric barrier and its position. After being treated for 3 s, the granules were triboelectrically charged in a vibratory device for 2 min. The charge the DBD-treated and untreated particles acquire by tribocharging was measured using a Faraday pail connected to an electrometer. Experimental results show that the air gap and the properties of the dielectric barrier can influence the mean value of the discharge current and enhance significantly the triboelectric charge of DBD-treated granules. Best results were obtained when the air gap did not exceed 4 mm and material with high permittivity was used as a barrier.