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Roger T. Bonnecaze, T. Brockett Hudson Professor in Chemical Engineering and Department Chair at the University of Texas at Austin, presents The Flow, Memory and Aging of Soft Particle Pastes as part of ChBE's Fall Seminar Series.
ABSTRACT:
Soft particle pastes are composed of deformable particles randomly packed into a dense suspension. Examples of soft particles include polymer coated colloids, compressed emulsions, polyelectrolyte microgels, and star polymers. Such pastes are important as rheological modifiers for food, materials and coating processes, and as friction reducers in cement pumping. In spite of the differences in the particle sizes and source of elasticity, all of these materials show similar rheological characteristics, memory and aging behavior. Experimental evidence of these phenomena will be presented. It will be shown that these effects arise from the non-linear interaction between hydrodynamic and elastic-like forces among particles and surfaces. Scaling analysis and detailed micromechanical models of elastohydrodynamic interactions are described and shown to match experimental observations for particle-wall slip. The micromechanical models are extended to simulations of concentrated suspensions to understand the fundamental nature of the observed bulk rheology of these unusual materials.
Unless otherwise noted, all seminars are held in the Molecular Science and Engineering Building in Room G011. Refreshments are served at 3:30 PM. The seminar starts promptly at 4:00 PM.
