DEFLOCCULATION OF CONCENTRATED AQUEOUS CLAY SUSPENSIONS WITH SODIUM POLYMETHACRYLATES

The ability of sodium polymethacrylate salts with various molecular weights (1200 to 30000 g.mol(-1)) to deflocculate concentrated aqueous suspensions (58 wt%) of two clays, widely used for stoneware ceramic tile production, was investigated. Rheological measurements were made in distilled water or in water containing calcium ions (O to 6 x 10(-3) mol.dm(-3)) to evaluate the practical applications of these salts as deffocculants in the ceramic tile industry. All slips presented a non-Newtonian behavior. Polymethacrylates with low molecular weights were the most efficient deflocculants for clay suspensions. The salts acted by an essentially electrosteric stabilization mechanism, in combination with a high sequestering ability toward flocculating cations. For their efficient deflocculating capabilities toward concentrated aqueous clay suspensions, sodium(I) polymethacrylates may be considered for practical industrial application, in particular for the preparation of liquid deflocculants.