Objective: Powder handling characteristics are of critical importance in manufacturing. However, many particulate forms are fine and cohesive, and provide a significant challenge to achieve controlled and suitable flow or fluidization. This can be attributed to the strong and uncontrolled attractive forces among particles. In this study, a novel particle engineering technology, intensive mechanical dry powder coating technique (or “mechanofusion”) is applied to reduce the attractive forces among particles in order to improve their flow and fluidization behaviours.

Methods: A fine (d50 ≈ 10μm) cohesive lactose powder was “mechanofused” with magnesium stearate. Powder flowability, fluidization, and aerosolisation behaviours were characterized using compressibility measurements, powder rheometry, and by aerosolisation tests.

Results: The results indicated that bulk density of lactose powder increased by over 140%, and the flowability reflected by Carr’s index decreased by 42% after surface modification. More detailed information on powder flowability was provided by powder rheometery, which showed the cohesion of the powder decreased by 90%. Aerosolisation tests demonstrated that modified powders were much easier to fluidize and achieved better dispersion performance.

Conclusions: The flowability and fluidization behaviours of a cohesive lactose powder were dramatically improved after an intensive mechanical surface modification process. This novel technique shows a promising potential to modify inter-particulate interactions of a powder by changing surface nano-structure and thus improve their performance during the particulate handling. The rheometer was also shown to be a very useful tool in characterizing the complex powder behaviours using one single system.