Effect of NH_4PAA adsorption on stability and rheology of TiO_2 suspension

The role of ammonium polyacrylate (NH 4PAA) in the dispersion of nanosized TiO 2 is investigated experimentally. The adsorption of NH 4PAA onto TiO 2 has been studied as a function of pH. The adsorption amount of NH 4PAA is found to decrease with an increase of pH. With the increase of NH 4PAA concentration, the isoelectric point for nanosized TiO 2 shifts from pH 5.9 to pH 2.7. The addition of NH 4PAA leads to a lower viscosity of high concentrated suspensions, and the rheological behavior of nano TiO 2 suspensions is strongly dependent on the amount of NH 4PAA. It turned out that an effective improvement of the stable and rheological properties of the solid suspensions investigated depends on definite amounts of NH 4PAA and definite pH ranges as well.