382978 The Medium Amplitude Oscillatory Shear (MAOS) of Semi-Dilute Colloid Dispersions - Third Harmonic of the Suspension Stress

Tuesday, November 18, 2014: 2:30 PM
M304 (Marriott Marquis Atlanta)
James Swan, Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA, A. Kate Gurnon, University of Delaware, Newark, DE and Norman J. Wagner, Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, DE

We study the response of semi-dilute colloidal dispersions under Medium Amplitude Oscillatory Shear (MAOS). Using an excluded annulus model of the hard-core repulsion and hydrodynamic in- teractions among the particles, we determine the third harmonic of the stress response of a colloidal dispersion in the pair limit. Importantly, the influence of hydrodynamic forces, both in magnitude and in character, on the MAOS of semi-dilute dispersions is made explicit through comparison of such nonlinear rheological properties while varying the ratio of the hard-core to hydrodynamic radius. We show through comparison with experiments that hydrodynamic forces have a considerable effect on the microstructure of dispersions undergoing MAOS. Consequently, the nonlinear, oscillatory rheology of semi-dilute suspensions is quite sensitive to non-conservative, hydrodynamic, forces. 

Extended Abstract: File Not Uploaded