Interaction and dispersion stability of alumina suspension with PAA in N,N '-dimethylformamide

The alumina suspension in N,N'-dimethylformamide (DMF) was studied in the presence of a polyacrylic acid (PAA) dispersant. The sedimentation measurements of the suspensions show that PAA can impart favorable dispersion stability to alumina in DNIF over a wide apparent pH (pH(a)) range. The adsorption of PAA on alumina and the zeta potential of the suspension are pH(a) dependent. FTIR-ATR spectroscopic studies reveal that the different interaction mechanisms between PAA and alumina work as a function of pH(a). But the observable difference of dispersion between pH(a) values of 2.6-12.7 is small according to the sedimentation experiments. This can be explained by a combination of the static effect of PAA dispersant and different sizes of steric barrier resulting from the configurational variation of PAA with changing pH(a) values. (C) 2009 Elsevier Ltd. All rights reserved.