(126d) Investigation of Granular Surface Roughness Effect on Electrostatic Charge Generation

Abstract：Electrostatic charge generation is a multivariable and complex process whose working mechanism has never been fully understood. The objective of this study is to investigate the effect of granule surface roughness on electrostatic charge generation. Two kinds of granule material, namely Polyvinyl chloride (PVC) and polypropylene (PP) were used with the granule size of 4mm in diameter and 2mm in height and in the shape of either cylinder or semi-cylinder. The working surfaces were grounded and the corresponding roughness ranged from 0.140 to 8.600 μm. Uneven surfaces were found to give rise to voids between two solids, where air stored in the voids was able to accelerate discharging. With the same roughness, PVC tended to generate more electrostatic charge than PP by one order of magnitude. For both materials, electrostatic charge generation first increased with surface roughness and then decreased. The maximum electrostatic charge generation was found to occur when the effects of interaction, contact area and voids discharging were at equilibrium. With the combined effect of humidity, surface roughness and contact area, highest electrostatics generation occurred near the mid-roughness point tested in this work. Humidity had more effect on electrostatic charge generation as the granule working surface had lower roughness.

Keywords: Electrostatic charge generation; Surface roughness, Granule.