Levich Institute Seminar Announcement, 02/27/2018
Steinman Hall, Room #312
(Chemical Engineering Conference Room)
Professor Joao Maia
Case Western Reserve University
Department of Macromolecular Science and Engineering
"Rheology and Microstructure of Dense and Semi-Dense Colloidal Suspensions"
The shear-thickening phenomenon and its physical origin have been the subject of numerous recent and not-so-recent experimental and theoretical studies. In a recent numerical study by our group, the role of hydrodynamic lubrication and frictional interactions in rheological response of dense and semi-dense colloidal suspensions has been explored. We could successfully replicate the whole range of continuous and discontinuous shear thickening regime. Formation of a frictional percolating network at high shear stresses was found to be the origin of discontinuous shear thickening behavior. On the other hand, hydro-clusters formed at low stresses that bring particles together and nucleate the frictional network are responsible for the continuous shear thickening behavior of such complex fluids. The observed microstructural and rheological changes of the colloidal suspension are indeed dictated by the interplay between the hydrodynamic and frictional interactions. Particle-Particle elastic interactions significantly influences the flow behavior and microstructure of such systems. It is expected that this effect will be enhanced in confined geometries. Herein, we report on the rheological behavior and microstructure development of soft to rigid colloidal suspensions in Pouseille flow in mildly and strongly confined geometries, and how they are changed from unconfined conditions.
BRIEF ACADEMIC/EMPLOYMENT HISTORY
BEng: 1992, Lisbon Technical University, Portugal
PhD: 1996, University of Wales Aberystwyth
1996-2009: University of Minho, Portugal, Department of Polymer Engineering
2009-Present: Case Western Reserve University, Department of Macromolecular Science and Engineering
MOST RECENT RESEARCH INTERESTS
- Soft Matter Physics, with an emphasis on structure/properties relationships under flow
- Extensional Rheology
- Rheology Applied to Macromolecular Technology, with an emphasis on the development of new functional multiphase polymeric materials, e.g. blends and composites.