Berlin 2015 – wissenschaftliches Programm
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DY: Fachverband Dynamik und Statistische Physik
DY 45: Focus: Disordered Systems, Glasses under Shear I (joint session CPP/ DY)
DY 45.6: Vortrag
Donnerstag, 19. März 2015, 11:30–11:45, C 243
Transient Rheology of Colloidal Suspensions - Shear Reversal — •Miriam Siebenbürger1, Fabian Frahsa2, and Matthias Fuchs2 — 1Helmholtz Zentrum Berlin, Germany — 2Universität Konstanz, Germany
At low deformations, colloidal glasses exhibit first a linear deformation, followed by a stress overshoot and the sheared steady state [1]. In this transition range from solid to fluid the reversal of the shear deformation can spend insights in the dynamics of the underlying structural transformations. Experimental investigations are performed by model suspension of thermo-sensitive colloids, consisting of a poly(styrene) core and a poly(N-isopropylacrylamide) shell. By a set of shear reversal experiments the aging effect often observed in experimental systems can be discussed separately from the structural transformations due to the shear. The height and the position of the minimum of the undershoots in the reversed shear flow is correlated with the deformation at the start of the shear reversal. All results for different shear rates and waiting times will be compared to the Mode Coupling Theory (MCT) and simulations, which show good agreement compared to the experimental results [2].
[1] C. P. Amann, F. Weysser, M. Fuchs, M. Siebenbürger, M. Krüger and M. Ballauff, J. Rheol. 57,149 (2012).
[2] F. Frahsa, A. Bhattacharjee, J. Horbach, M. Fuchs and T. Voigtmann, J. Chem. Phys. 138, 12A513 (2013).