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IRTG / Soft Matter Science
Freiburger Materialforschungszentrum
Stefan-Meier-Str. 21
79104 Freiburg, Germany


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You are here: Home Events Prof. Nobert Willenbacher

Prof. Nobert Willenbacher

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Institute for Mechanical Process Engineering and Mechanics, Applied Mechanics, Karlsruhe Institute of Technology (KIT), Gotthard-Franz-Str. 3, D-76131 Karlsruhe, Germany

  • Seminar
When Jul 31, 2014
from 02:15 PM to 03:00 PM
Where Seminarraum A, FMF, Stefan-Meier-Str. 21, Freiburg
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The presentation will cover three aspects: 1. Fluidization of highly concentrated colloidal dispersions with weak attractive interactions. The phenomenon will be discussed for glassy as well as crystalline aqueous polymer dispersions. Aspects of technical application, predictions from mode coupling theory for glassy systems and phase behavior of crystalline samples will be discussed. Aqueous colloidal dispersion consisting of short-range repulsive polystyrene-butylacrylate (PS/BA) particles serve as model systems. Linear polyethylene oxide (PEO) has been used as non-adsorbing polymer to introduce the depletion attraction. For determination of flow profiles in microchannels fluorescent particles were added and their velocity was tracked using video microscopy. 2. The aggregation of highly concentrated colloidal dispersions in elongational flows will be discussed. A simple device based on a capillary rheometer has been used to induce and detect aggregates. Trace amounts of micron-sized impurities/aggregates are shown to be the origin of this phenomenon. The effect of flow kinematics and primary colloidal particle stability will be addressed. 3. The phase behavior and linear viscoelastic properties of hard sphere like aqueous colloidal dispersions has been investigated using multi particle tracking microrheology. This techniques allows for a direct imaging of the particle concentration fluctuation length scale in nanoparticle dispersions in the two-phase coexistence regime.
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