Regensburg 2019 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 30: Complex Fluids and Colloids, Micelles and Vesicles (joint session CPP/DY)
CPP 30.1: Hauptvortrag
Mittwoch, 3. April 2019, 09:30–10:00, H14
Microstructural transitions and characterization of capillary suspensions — Sebastian Bindgen1, Frank Bossler2, Irene Natalia1, and •Erin Koos1 — 1Department of Chemical Engineering, KU Leuven, Leuven, 3001, Belgium — 2Institute for Mechanical Process Engineering, Karlsruhe Institute of Technology, Gotthard-Franz-Str. 3, 76131 Karlsruhe, Germany.
Suspensions can exhibit a wide range of rheological behaviors that are closely linked to both the bulk particle structure as well as the microstructure including direct particle contacts. Graph theory offers methods and parameters that can be used to analyze complex structures. This method is demonstrated using ternary liquid-liquid-solid systems, which exhibit a wide variety of different morphologies depending on the ratio of the three components. We analyze these networks using the coordination number and clustering coefficient. These parameters are compared to the measured storage and loss moduli.
These capillary suspension networks also exhibit atypical rheological behavior. For instance, a negative normal stress difference is observed from re-orientation of the flocs into the vorticity direction during shearing. Typically, systems with negative normal stress differences have either high volume concentrations and are shear thinning, or are shear thickening with very low particle concentrations. In contrast, the capillary suspensions we report here have a 25% solid concentration and are shear thinning; a combination that has never before been reported in literature.