Accentuated shear thinning of soft sphere suspensions

ORAL

Abstract

Suspensions of soft colloidal particles exhibit highly unusual rheological behaviors; surprisingly, despite the importance of these materials in a wide range of applications, the underlying physical mechanisms remain poorly understood. Experiments show that suspensions of soft particles exhibit a highly pronounced shear thinning; this decrease in viscosity with increasing shear rate far exceeds the shear thinning observed in suspensions of solid particles. We use soft microgel particles as a model system to elucidate this behavior. Our experimental system allows us to study the mechanical behavior both macrosopically and locally, at the scale of the colloidal particles themselves. We combine data obtained at different length scales to arrive at a simple picture of the observed accentuated shear thinning.

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Authors

  • Hans Wyss

    Harvard University

  • Johan Mattsson

    Harvard University, Chalmers University of Technology, Sweden, Chalmers University of Technology

  • Alberto Fernandez-Nieves

    Harvard University, Georgia Institute of Technology

  • Giovanni Romeo

    University of Naples Federico II, Italy

  • Melaku Muluneh

    Harvard University

  • Zhibing Hu

    University of North Texas

  • David Weitz

    School of Engineering and Applied Sciences, Harvard University, Harvard University, Department of Physics and HEAS, Harvard University, SEAS, Harvard University, Harvard School of Engineering and Applied Sciences, and Department of Physics, Harvard University, HSEAS, Harvard University