A vane yield stress technique was employed to study depletion interaction in concentrated ZrO2 suspensions containing an adsorbed and a free polymer. The adsorbed polymer was a low molecular weight polyacrylic acid. Two free polymers, polyvinyl alcohol and polyethylene oxide, were used separately. The depletion interaction caused an increase in the yield stress and the extent of increase varied with the free polymer concentration φ(p). Analysis of the depletion interaction is centred on the pH of maximum yield stress or zero zeta potential. The experimental depletion energy obtained from yield stress analysis was compared with that calculated from the pragmatic theory [A. Jones and B. Vincent, Colloids Surfaces, 42 (1989) 113-138]. The agreement between experimental and theoretical depletion energies, assuming particle pair interaction, is reasonable. A maximum in the depletion energy was observed both experimentally and theoretically. However, the experimental maximum occurs at a lower φ(p) value.
|Number of pages||8|
|Journal||Colloids and Surfaces A: Physicochemical and Engineering Aspects|
|Publication status||Published - 1 Nov 1996|