Effects of Acrylic acid/Acrylic Ester Copolymer on the Characterization of Bi_4Ti_3O_(12) Aqueous Suspensions

An acrylic acid/acrylic ester copolymer was employed as a dispersant for Bi4Ti3O12 aqueous suspensions. Surface chemistry of the suspensions was investigated by several techniques. Zeta-potential measurements showed that the isoelectric point (IEP) of Bi4Ti3O12 was shifted from pH=4 for pure Bi4Ti3O12 to low pH regions in the presence of copolymer. FTIR spectra indicated that copolymers adsorbed on Bi4Ti3O12 surface via physical interaction. The adsorption amount varied with different copolymer content and reached to the maximum values when 1.5wt% (dry mass base) copolymer was added, then decreased because of the deadsorption of the copolymer. The rheology of Bi4Ti3O12 aqueous suspensions was also studied. The results suggested that the stabilization of the suspensions was improved remarkably by the adsorption of the copolymer on Bi4Ti3O12 surface. The stability of the suspensions was attributed to the electrostatic mechanism when the copolymer concentration was less than 1.5wt% and may be the depletion mechanism when the copolymer concentration was higher than 2.0wt%.