SHEAR-INDUCED DIMERIZATION

The Yamada-Kawasaki theory of nonlinear response was applied to the ca lculation of the frequency and shear-rate dependent shear viscosity of a dilute Brownian suspension of harmonically bound dumbbells. When th e dumbbells were allowed to dimerize, as implemented by the Wertheim t heory of association, the resulting fluid displayed exhibited shear-th inning and shear-thickening regimes. Head-to-head dimerization led to shear thinning, and for shear thickening to occur, the rotational corr elation time of the dimers must be commensurate with those of the mono mers, The present findings were evaluated in light of the observed she ar-induced coagulation in micellar solutions. (C) 1997 American Instit ute of Physics.