(4b) Flow Optimization in Cohesive Powder Blends: Identifying and Modeling Impact of Shape and Size on Observed Cohesivity Minimum

Authors: 
McClure, S., Merck Sharp & Dohme Corp.
Goldfarb, D., Merck & Co., Inc
Conway, S. L., Merck & Co., Inc.
Nakagawa, H., Merck & Co., Inc
Gentzler, M., Merck
Through analysis of particle morphology, particle size, and compositional influences, we present experimental case studies revealing unexpected transitions in flowability and cohesion of two binary powder blend systems containing components with elongated (needle-like) and more spherical particle morphologies. We explore interactions between the needle-like and the more spherical components in the blend to explain these transitions, and optimal concentrations to improve flowability are identified. We observe, for cohesive binary mixtures, a local minimum phenomenon, in which a blend with a small amount of needle-like morphologies exhibits improved flowability compared to the single component system. A surface-area based model considering particle geometry, surface coverage, and blend composition is implemented to understand and predict trends in flowability. Discrete Element Method (DEM) modeling is employed to study the structure and particle interactions in simulated binary powder blends containing spherical and elongated particle morphologies. These results should translate both to the improved understanding of mixed component morphology systems and to a novel approach towards pharmaceutical product formulation optimization.