Electrostatic Charge Generation due to Shear Deformation of Pharmaceutical Powders

In powder handling operations, such as mixing, conveying, sieving and milling, particles frequently make contact with each other and the walls of the processing equipment. During these interactions, the electrification of particles takes place, commonly known as tribocharging. This paper focuses on investigating the tribocharging characteristics of bulk powders under shear deformation. In particular, the effect of shear strain and shear rate on the charge generation is analysed. An annular shear cell, modified for electrostatic charging, is used for applying a shear strain to a bed of pharmaceutical powders. α-lactose monohydrate particles, widely used as an excipient for pharmaceutical formulations, is used as a model system. It is shown that the charge on the particles increases with the applied shear strain.