Insights into the role of electrostatic forces on the behavior of dry pharmaceutical particulate systems

Under different charging conditions, particles can be either attracted or repulsed by each other, causing powder agglomeration or segregation. Such behavior can be detrimental in many processes aimed at achieving particulate mixture homogeneity. Consequently, the effects of electrostatic charges on mixing kinetics must be well understood to insure a high level of process control, product quality, and reproducibility.

In Part 1, an electrostatic charger is used to evaluate the ability of the studied particles to develop and retain an induced charge at the surface for a fixed period of time. Part 2 assesses the natural electrostatic charge developed by powders sliding across a stainless steel, plastic, or Tyvek chute. In Part 3, 2 binary systems were formed according to an experimental design under different charging conditions, and their behavior was quantified by measuring the degree of agglomeration attained.

This work has shown that each raw material develops a different charge according to its physico-chemical properties and the type of contact surface. Electrostatic charges influence the creation of agglomerates under certain conditions.

The presence of electrostatic charges must be accounted for in any effort to maximize mixing efficiency.