(748c) Investigating the Effect of Mechanical and Material Properties on Tribocharging of Pharmaceutical Powders

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. Pharmaceutical powders are quite prone to electrostatic charging by colliding and sliding contacts with walls and other particles. In  formulation processes, particle charging is often a nuisance and can cause problems in the manufacture of products, such as  powder flow,   fill level and dose uniformity. For a fundamental understanding of the 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 charging, 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. 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. A triboelectric series of pharmaceutical materials was generated which seems to suggest that electrons are the charge transfer agent. An effort was made to correlate tribocharging of pharmaceutical powders to material properties such as cohesive energy density (CED), surface energy and Young’ modulus