(318g) Yielding Processes in Dense Colloidal Suspensions Using Asymptotically Nonlinear Material Functions

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