Mechanical dispersion of viscous liquids in sheared particulate systems

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1236633PI: Wassgren This research project focuses on developing an improved understanding of the transfer of liquid through particle-particle contacts, often referred to as ?mechanical dispersion?, in particulate systems. In particular, this project seeks to improve our scientific methodology, understanding, and quantitative predictive ability of these systems by developing (1) a novel experimental approach for investigating the spatial distribution of liquid in particulate systems and (2) an experimentally validated computational model for predicting the liquid dispersion in more complex, industrially relevant manufacturing equipment. The experiments will be performed in-situ using an x-ray tomography method, therefore retaining the liquid spatial distribution and time evolution of the mechanical dispersion process. These in-situ measurements differ from those reported in the literature, which assessed the evolution of the liquid dispersion process by removing particles from the experimental device. The experimentally validated computational model will simulate the dynamics of particles in a sheared system, taking into account inter-particle contacts and the effects of the liquid ?bridge? joining two or more particles. The dispersal of a binding or coating agent, such as a liquid or solid material, onto particles is commonplace in many industrial processes. In the pharmaceutical industry, for example, such a mechanism is used to combine inactive and active ingredient powders into granules, which are then used to make tablets or capsules. Most previous work focused on systems involving liquid coatings that dry quickly and do not transfer significantly from particle to particle. The transfer of liquid through mechanical dispersion has rarely been investigated, which is unfortunate since in many industrial processes the coating liquid is too viscous to be sprayed and, thus, is poured onto the powder bed and dispersed through particle contacts. At present, the design and optimization of these systems are carried out through trial and error, resulting in significant time for development, loss of materials, and potentially reduced product effectiveness. Successful completion of the objectives of the present study will greatly enhance our understanding of the processes involved in the mechanical dispersion of liquid in particulate systems, as well as our ability to quantitatively predict and design the operation of a mechanical dispersion-driven system.