(421w) Investigating the Tribocharging of Pharmaceutical Powders in a V-Blender : Experiments and Simulations

Electrostatic charging via contact electrification or tribocharging refers to the process of charging of two solid surfaces when they are brought into contact and separated. In pharmaceutical formulation processes, particle charging is often a nuisance and can cause problems in the manufacture of products, such as  powder flow, and  fill level and dose uniformity. For a fundamental understanding of  powder triboelectrification, it is essential to study charge transfer under well-defined conditions. Hence all experiments in the current study were conducted in a V-blender located inside a glove box with a controlled humidity of 20%.  To quantify the electrification of powders, different contact surfaces viz. PVC, aluminum, Teflon, PMMA were employed along with two pharmaceutical excipients and two drug substances. Tribocharging of drug-excipients mixtures was attempted via a blending process. Moreover, the collisional nature of triboelectrification was investigated using a 3D DEM model incorporating charge transfer and electrostatic forces. For the pharmaceutical materials, the chemical potential were calculated using MOPAC, a semi-empirical molecular orbital package which has been previously employed for the solid state studies and molecular structure predictions. Based on the chemical potential values a triboelectric series of pharmaceutical materials was generated which seems to suggest that electrons are the charge transfer agent.