376671 Yielding Processes in Dense Colloidal Suspensions Using Asymptotically Nonlinear Material Functions

Tuesday, November 18, 2014: 2:00 PM
M304 (Marriott Marquis Atlanta)
Mansi Agarwal, Materials Science and Engineering, University of Illinois at Urbana Champaign, Urbana, IL, Randy H. Ewoldt, Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL and Charles F. Zukoski, Department of Chemical & Biomolecular Engineering, University of Illinois at Urbana Champaign, Urbana, IL

Nonlinear rheological properties of dense colloidal suspensions were studied using asymptotically nonlinear material functions in oscillatory shear as introduced in [1]. Silica nanoparticles of diameter 40 nm were dispersed in low molecular weight polyethyleneglycol (PEG) to mimic a hard-sphere colloidal suspension with volume fractions ranging from 0.4 to 0.46. The asymptotically nonlinear properties provide robust definitions of critical strain as a function of frequency, and can be used to infer changes in structure as the suspension enters in the non-linear regime. These material functions therefore provide a better understanding of the yielding process in colloidal systems and we predict that a similar approach can be used for non-hard sphere colloids.

 [1] Ewoldt et al, Rheologica Acta, 2013


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