(420a) Comparison of Particle Breakage Models Accounting for Particle Size-Shape Evolution

The pharmaceutical industry frequently produces particles by solution crystallization, and these particles are often needle shaped or acicular crystals with high aspect ratios [1]. Because the particle shape can affect the pharmaceutical’s bioavailability, controlling the particle shape is essential. From a processing perspective, controlling particle shape is important because affects particle flowability and unit operations such as tableting. Therefore, it would be very useful to have accurate models that account for changes in particle shape due to mechanisms such as breakage. Despite the importance of such models to designing and controlling these processes, there are very few models available that account for particle shape evolution due to breakage. The research objective is to develop more accurate population models for breakage of high aspect ratio crystals.

Previous experimental research with needle-shaped urea crystals agitated in a dilute slurry showed the effects of breakage at two different breakage rates. Data analysis showed that the aspect ratio of the child particles produced were predominantly a function of the child particle major axis length, but not a function of the child particle minor axis length.

Novel two-dimensional (size, aspect ratio) population balance breakage models are presented and compared with each other as well as with the experimental data. A common simplifying assumption in modeling needle-shaped particle breakage is to assume binary breakage where the original parent particle breaks along a plane perpendicular to the major axis. This presentation shows that this simplified model is not sufficient to explain the experimental results.