Dresden 2014 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 13: Glasses (original: DY, joined by DF, CPP)

CPP 13.7: Vortrag

Montag, 31. März 2014, 16:45–17:00, ZEU 146

Glasses of binary colloidal mixtures in the quiescent state and under shear — •Tatjana Sentjabrskaja, Marco Laurati, and Stefan Egelhaaf — Condensed Matter Physics Laboratory, Heinrich-Heine Universität Düsseldorf, D-40225 Düsseldorf, Germany

We investigate mixing effects on the glass state of binary colloidal hard sphere mixtures with large size asymmetry (size ratio 1:5). Increasing the amount of small spheres in a system of large ones, a glass-glass transition is observed, where the large particles, initially caged by the large spheres, become localised in a cage of small spheres [1]. During the transition, the dynamics accelerate and a strong reduction of the yield strain as a result of the shift of random close packing is observed[2].

The results of rheology are compared to measurements of the dynamics of particles under shear. The super-diffusion typically associated with stress overshoots [3] becomes more pronounced for mixtures in which the dynamics are increasingly arrested. Moreover, we observe different degrees of shear-induced constriction depending on mixing ratio, which closely follow changes in the magnitude of the stress overshoot.

[1] T.Sentjabrskaja et al., AIP Conf.Proc., 1518, 206, 2013.

[2] T.Sentjabrskaja et al., Soft Matter, 9(17), 4524- 4533, 2013.

[3] M.Laurati et al., J. Phys.: Condens. Matter, 24, 464104, 2012.