Effect of varied powder processing routes on the stabilizing performance and coordination type of polyacrylate in alumina suspensions

The influence of initial pH and energy input during suspension homogenization on the stabilizing performance and coordination type of commercial available polyacrylate dispersant were studied. Additionally to widely used rheology and electroacoustic measurement techniques the alumina suspensions were analysed with centrifugal separation and in situ ATR-FTIR to study the impact of varied powder processing in detail. In contrast to zeta potential analysis and viscosity measurements only the determination of sedimentation properties by centrifugal separation shows the effect of macroscopic changes in powder processing. A combination of positively charged alumina surface and a high shear homogenization leads to the most stable suspension. Accordingly ATR-FTIR results show a correlation between improved suspension stability and inner-sphere coordination of polyacrylate. Moreover it was possible to determine an optimal pH range for inner-sphere adsorption. It can be shown that macroscopic changes in powder processing influence the coordination of dispersant and thus the suspension stability. (C) 2011 Elsevier Ltd. All rights reserved.