Objectives:

Segregation of formulated bulk pharmaceutical powders due to electrostatic forces is an issue of great technological and scientific interest.  The formulation, material properties and environmental conditions such as humidity and temperature affect the phenomenon, but the underlying mechanisms are not well-understood. The specific aims of this project are as follows.

• To charge and characterise various components of a pharmaceutical formulation by impact charging using the methodology that has been developed in a parallel research programme. 
• To develop microscopic techniques for visualisation and measurement of segregation by the use of automatic image processing and analysis.
• To investigate the degree of mixing for both charged and uncharged samples.
• To investigate the effect of shearing on charge generation and segregation using an annular shear cell.
• To investigate the relationship between charge generation and the mechanical properties of individual particles within the formulation that are relevant to the process, such as the contact potential difference and work function, Young's modulus of elasticity, hardness, adhesion, as influenced by humidity and temperature.
• To correlate the bulk segregation behaviour to single particle properties by the Distinct Element Method.
• To develop the methodology for quality control.

Figure  A tabletting machine, where segregation can present problems.