Does electrostatic charge affect powder aerosolisation?

To study if electrostatic charge initially present in mannitol powder plays a role in the generation of aerosols, mannitol was unipolarly charged to varying magnitudes by tumbling the powder inside containers of different materials. The resulting charge in the powder was consistent with predictions from the triboelectric charging theories, based on the work function values from literature and electron transfer tendencies from measurement of contact angle. The latter generated a parameter, gamma(-)/gamma+, which is a measure of the electron-donating capacity relative to the electron-accepting tendency of material. Lowering the work function value or increasing the gamma(-)/gamma+ ratio of the container material resulted in mannitol being more negatively charged, and vice versa. After charging, the powder was dispersed from an Aerolizer(R), at 30 and 60 L/min, to study the aerosol performance. Irrespective of the charge level, the powder showed similar fine particle fraction, emitted dose and device retention at a given flow rate, indicating that charge induced by different containers during tumbling does not play a significant role in mannitol powder aerosolisation.