Rheology of non-Newtonian fluids: A new flow equation for pseudoplastic systems

Abstract

On the assumption that pseudoplastic flow is associated with the formation and rupture of structural linkages a new flow equation is derived. The equation takes the form $\text{ƞ = ƞ}{}_{\mathrm{\infty }}\text{+}\text{ƞ}{}_0\text{− ƞ}{}_{\mathrm{\infty }}\text{1 + αD}{}^{\mathrm{<mtext>2</mtext><mtext>3</mtext>}}\text{,}$ where D = rate of shear, η₀ = limiting viscosity at zero rate of shear, η_∞ = limiting viscosity at infinite rate of shear, and α is a constant associated with the rupture of linkages.

Graphical methods for evaluating the three constants η₀ , η_∞ , and α are presented.

Experimental data are presented on a wide range of pseudoplastic systems, ranging from suspensions to optically clear solutions, in both aqueous and nonaqueous media. In all cases the results conform to the equation with a high degree of accuracy over a wide range of shear rates.