Schematic mode coupling theories for shear thinning, shear thickening, and jamming

Mode coupling theory (MCT) explains several aspects of the glass transition in colloids. Developments of MCT, from rational foundations in statistical mechanics, account qualitatively for nonlinear flow behavior such as the yield stress of a hard-sphere colloidal glass. Such theories only predict shear-thinning behavior, whereas in real colloids, both shear thinning and shear thickening can be found. The latter observation can, however, be rationalized by postulating an MCT vertex that is not only a decreasing function of strain rate but also an increasing function of stress. Within a highly simplified, schematic MCT model this can lead not only to discontinuous shear thickening but also to complete arrest of a fluid phase under the influence of an external stress.