Dynamics of shear-thinning suspensions of core–shell structured latex particles

The rheological behavior and microstructure of shear-thinning suspensions of core–shell structured carboxylated latex particles were examined. The steady shear viscosity of the suspension increased with increasing dissociation of the carboxyl groups or increasing particle concentration, however the critical shear stress σcσc and inter-particle distance ξ   of the microstructure did not change. With increasing particle diameter, σcσc increased and ξ   decreased. These results were consistent with a Brownian hard sphere model, in which competition exists between the bulk mass transfer due to the applied field and diffusion of the particles. We confirmed that σcσc depends on ξ  , as expressed by σc=3kT/4πξ3σc=3kT/4πξ3. This relationship is consistent with the dynamics of a Brownian hard sphere model with particle diameter ξ. Thus the dynamics of shear-thinning suspensions of core–shell particles can be explained by a Brownian thermodynamic model.

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