On the rheology of thixotropic and rheopexic suspensions

Semi-empirical equations are derived that describe the dependence of shear stress on shear rate during the flow of a one-component suspension. The suspension is considered as consisting of two fractions: single grains of the solid phase and their dimers, between which a reversible dimerization reaction occurs. In this case, the dimerization of single grains is considered as a reaction with an invariable rate constant, and the dissociation of dimers is considered as an inverse reaction with a rate constant that increases linearly with the shear rate. The equations are based on the Krieger-Doherty formula, generalized to the case of a multicomponent suspension.