SHEAR THINNING VS SHEAR THICKENING IN ASSOCIATING FLUIDS

When one-bond Frenkel dumbbells are allowed to dimerize, as analyzed u sing the Wertheim theory of association, the resulting fluid exhibits shear thinning or shear thickening behaviors. In contrast, when Gaussi an chains undergo shear-assisted association, only shear thickening is possible. The present theory of shear-induced association of non-Newt onian fluids is applied to interpret the shear thickening seen in equi molar solutions of the CTAB (cetyl trimethyl ammonium bromide) micelle s and sodium salicylate. Also derived in this study are the frequency dependent Newtonian viscosity and the non-Newtonian viscosity for a di lute Brownian suspension of two-bond freely jointed Frenkel dumbbells. (C) 1998 American Institute of Physics.