Plasticity of Highly Concentrated Suspensions

The rheological properties of aluminum suspensions in low-molecular-weight poly(ethylene glycol) have been systematically studied within a wide range of concentrations up to the ultimate content of the solid phase (about 70%). As the concentration of dispersed particles is increased, the rheological properties evolve from a Newtonian fluid to an elastoplastic solid. In the region of the flowable state, the studied dispersions have no yield stress. However, above a certain concentration, which is considered to be a mechanical glass transition, the suspensions become non-flowable. At higher concentrations, a region of elastoplastic state of highly concentrated systems arises, which has not yet been considered as we know. The boundaries of this region have been determined and the dependences of the characteristics of elasticity and plasticity on stress have been obtained. This region corresponds to the ultimate degrees of filling and is of importance for contemporary additive technologies and so-called “powder injection molding .”