title: Triboelectrification of pharmaceutical powders by particle impact.
abstract: Pharmaceutical powders are very prone to electrostatic charging by colliding and sliding contacts with walls and other particles. In pharmaceutical formulation processes, particle charging is often a nuisance and can cause problems in the manufacture of products, such as affecting powder flow, and reducing fill and dose uniformity. For a fundamental understanding of the powder triboelectrification, it is essential to study charge transfer due to a single contact of a particle with a target plane under well-defined physical, mechanical and electrical conditions. In this study, charge transfer due to a single impact of a particle against a stainless steel target was measured for alpha-lactose monohydrate, aspirin, sugar granules and ethylcellulose. The amount of transferred charge is expressed as a function of impact velocity and impact angle as well as the initial charge. The maximum contact area during impact between a particle and a target plane is estimated by an elastic-plastic deformation model. It is found that the transferred charge is a linear function of the contact area. For a given material, there is an initial particle charge for which no charge transfer occurs due to impact. This is found to be independent of impact velocity and angle, and is hence viewed as a characteristic property, which is related to the contact potential difference and tribo-electric series of the sample powders.
authors.affiliation: Institute of Particle Science and Engineering, University of Leeds, Leeds LS2 9JT, UK.
authors.forename: Hideo
authors.initials: H
authors.lastname: Watanabe
authors.forename: Mojtaba
authors.initials: M
authors.lastname: Ghadiri
authors.forename: Tatsushi
authors.initials: T
authors.lastname: Matsuyama
authors.forename: Yu Long
authors.initials: YL
authors.lastname: Ding
authors.forename: Kendal G
authors.initials: KG
authors.lastname: Pitt
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Maruyama
authors.forename: Shuji
authors.initials: S
authors.lastname: Matsusaka
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Masuda
mesh_terms: D002626:Chemistry, Pharmaceutical; D004548:Elasticity; D004735:Energy Transfer; D008956:Models, Chemical; D010316:Particle Size; D010969:Plastics / Q000737:chemistry*; D011208:Powders / Q000737:chemistry*; D055672:Static Electricity
chemical_list: D010969:Plastics; D011208:Powders