Effect of PEO/PPO type triblock copolymers on dispersion behaviour of aqueous alumina suspensions

Abstract

The aim of this study was to investigate the stability and dispersion behaviour of aqueous alumina suspensions in the presence of polyethylene oxide-polypropylene oxide-polyethylene oxide (PEO/PPO/PEO) type block copolymers. The influence of water soluble triblock copolymers with molecular weight ranging from 2900 to 12600 g/mole were tested at Φ = 0.125, 1, 10, 20 vol % solid loading alumina suspensions by rheological, turbidity, sedimentation and surface tension measurements. The results indicate that an alternative dispersant for alumina suspensions is the PEO/PPO triblock copolymers. Their stabilisation mechanism was attributed to the depletion stabilisation. Rheological measurements indicated that these block copolymers (at high EO percentages) coupled with ultrasonic treatment have a positive effect on the dispersion of the agglomerated alumina suspensions. It was not possible to create stable dispersions in the absence of ultrasonic bath treatment. Turbidity measurements at Φ = 0.025, 0.125 vol % showed that, alumina suspensions with PEO/PPO added were stable and have higher turbidity values than block copolymer free suspensions.