The effects of molecular weight (MW) and concentration of polyacrylic acid (PAA) on the yield stress τy of ZrO2 suspensions were evaluated. The Mw range studied was from 1656 to 750000. The effect of adsorbed polyelectrolyte on the forces between particles was determined by focussing on the pH at which zero zeta-potential (ζ=0) is observed in the presence and absence of polymer. At this ζ=0 condition a maximum in yield stress (τymax) is observed. Low molecular weight PAA imposes a steric (repulsive) interaction energy which is gradually replaced by a bridging (attractive) energy as the molecular weight is increased. The shift in τymax and the pH at which ζ=0 both show systematic changes with Mw as electrostatic, steric, van der Waals and bridging forces change in relative importance.
|Number of pages||10|
|Journal||Colloids and Surfaces A: Physicochemical and Engineering Aspects|
|Publication status||Published - 10 Feb 1995|