Micro-particle adhesion: Measurement and simulation

Dave Kumar Balachandran, Purdue University

Abstract

Solids processing unit operations are a basic component of most manufacturing processes, even when the final product is not strictly a dry solid. Processes like particle flow, mixing, storage, fluidization, and compaction are greatly affected by the cohesive forces between particles within powders and adhesive forces between powder particles and process surfaces. The ability to "engineer" particles with desirable handling properties represents an opportunity to reduce bottlenecking and overall manufacturing costs. The key parameters affecting particle cohesion and adhesion must be identified, quantified, and modeled to provide a science-based approach to manufacturing decision-making, improvement of existing process equipment, and materials selection and design. This thesis work focuses on the development of a detailed understanding of microparticle adhesion and a refinement of an experimentally validated modeling framework. While a number of surface forces become relevant when the primary particle diameter is reduced to 10 μm or below, the van der Waals (vdW) force dominates the interaction when relative humidity and electrostatics are minimized. A number of key parameters can have a profound effect on the strength of the vdW force, but this work is limited to characterizing particle size, particle shape, and surface roughness effects. The development of a novel particle tomography technique to simultaneously characterize particle shape and roughness using a focused ion beam and scanning electron microscope is emphasized. While this work examined materials and model systems that were of interest to the pharmaceutical industry, the insights gained in understanding particle-level adhesion phenomena are applicable to all particulate systems.

Degree

Ph.D.

Advisors

Beaudoin, Purdue University.

Subject Area

Chemical engineering|Pharmacy sciences

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