(479e) Effects of Particle Shape on Shear-Induced Aggregation/Fragmentation and Viscosity of Boehmite Crystal Suspensions

Authors: 
Chun, J., Pacific Northwest National Laboratory
Krzysko, A., Washington State University
Anovitz, L., Oak Ridge National Laboratory
Ivory, C. F., Washington State University
Ilavsky, J., Argonne National Laboratory
Kuzmenco, I., Argonne National Laboratory
Schenter, G., Pacific Northwest National Laboratory
Clark, S., Pacific Northwest National Laboratory
A recent study showed that a sharp-edged non-spherical shape play a critical role for dynamics of particle attachment of boehmite nanocrystals due to orientation-dependent particle interactions. We here further studied the effects of the particle shape on macroscopic-scale phenomena in the presence of flows by utilizing a combination of capillary rheometry and in-situ wide- small- and ultra-small angle X-ray scattering (WAXS, SAXS, USAXS), combined with characterizations of a flow field from computational fluid dynamics (CFD). Using anisotropic diffusivity calculations for the particles/aggregates and scaling arguments, we analyzed the scattering data and viscosity based on coupling between particle forces, colloidal stability, aggregation, and fragmentation under the flow field, which provides reasonable explanations. Our study demonstrated that the effect of the particle shape can be conceptually analogous to that of a repulsive particle force for understanding the suspension viscosity.