Dispersion of Al2O3 concentrated suspensions with new molecules able to act as binder

The objective is to define and synthesise molecules with a double function of dispersant and of binder. New acrylic copolymer molecules containing both carboxylic groups expected to bring a dispersant contribution and hydroxyl vinyl groups expected to bring a binder contribution were synthesised. The fraction of these two types of groups can be adjusted to balance the dispersion and the binder contributions. In a first step, the effect of these acrylic copolymer molecules on the interactions between alumina particles in aqueous suspension and on the rheology of concentrated suspensions was studied. Carboxylic groups allow adsorption of acrylic copolymers onto the alumina surface and can promote sufficient electrostatic repulsive forces to obtain a good state of dispersion. The amount of carboxylic groups controls the density of charge of the particle surface and hence, the ability of the copolymer to act as a dispersant. A low amount (0.6 wt.%) of a copolymer containing 35% of carboxylic groups, leads to stable suspensions with a critical powder leading of 80 wt.% corresponding to 50 vol.%.