Hamburg 2001 – wissenschaftliches Programm

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DY: Dynamik und Statistische Physik

DY 13: Statistische Physik (Allgemein) II

DY 13.4: Vortrag

Montag, 26. März 2001, 11:15–11:30, S 7

Dynamics of concentrated colloidal suspensions: Diffusion, Aggregation and Gelation — •Frank Scheffold, Sara Romer, Hugo Bissig, Veronique Trappe, and Peter Schurtenberger — Departement für Physik, Universität Freiburg, CH-1700 Freiburg

We have studied the properties of destabilized concentrated colloidal suspensions undergoing a transition from sol to gel. Using diffusing wave spectroscopy (DWS) in a novel two-cell geometry [1] we obtain valuable information about the local properties of fluid and solidlike turbid media. Our experiments cover such different materials as polystyrene latex suspensions and gels, ceramic green bodies and casein micellar gels (yogurt). We find that for a destabilized colloidal suspension undergoing a liquid-solid transition the gel point can be accurately determined using DWS. Furthermore for polystyrene particle gels at different concentrations (up to 30% in volume) we develop a link between the dynamical properties of the individual particles in the network, as deduced from DWS, and the macroscopic elasticity of the gel G’. Excellent quantitative agreement is found when comparing the results obtained from DWS to (classical) rheological measurements.

[1] S.Romer, F. Scheffold and P. Schurtenberger, Phys. Rev. Lett. 85, 4980 (2000), www.unifr.ch/physics/mm/SCMP_Publications.html