Paper Number
SC36
Session
Suspensions & Colloids
Title
Controlling shear thickening in colloidal dispersions through the addition of nanoclay, polymer, and nonBrownian particles
Presentation Date and Time
October 17, 2018 (Wednesday) 3:45
Track / Room
Track 1 / Galleria I
Authors
- Wagner, Norman J. (University of Delaware)
- Lawton, Jacob (Univ. Delaware, Chemical & Biomolecular Engineering)
- Katzarova, Maria (University of Delaware)
Author and Affiliation Lines
Norman J. Wagner, Jacob Lawton, and Maria Katzarova
University of Delaware, Newark, DE
Speaker / Presenter
Wagner, Norman J.
Text of Abstract
Colloidal dispersions exhibit shear thickening and it is often desirable to control the onset and extent of this rheological response through formulation. Controlling particle size, shape, surface interactions, and solvent properties can all be used to systematically and predictively vary the shear thickening behavior of a suspension, but more recently it has been shown that the addition of other particles can dramatically affect the underlying shear thickening of the base colloidal suspension while affecting other aspects of the flow behavior in a qualitatively different manner. In this work, new nanoclay particles are added to a model, well-studied colloidal dispersion and the shear rheology measured with varying nanoclay amount and nanoclay aspect ratio. The results demonstrate that very small additions of nanoclay can dramatically enhance the shear thickening response of the colloidal dispersion. Evidence for depletion interactions in the mixture is observed in the low shear rheology. Measurements suggest the nanoclay may be enhancing the hydrodynamic interactions via confinement of the colloidal dispersion, as has been previously reported for the addition of nonBrownian cubes and spheres to the same colloidal dispersion.(Cwalina et al. JOR 2015, AIChE 2017) Scaling of the shear thickening exponent with confinement supports this viewpoint and provides a method for rational design of dispersions with specific rheological gain. These results are also analyzed withi the context of simulations showing the enhancement of hydrodynamic interactions due to confining hard walls by Swan and Brady JFM 2011 as well as by Bian et al. JNNFM 2014.