Surface chemistry and rheological behaviour of titania pigment suspensions

Gayle E. Morris, William A. Skinner, Peter G. Self, Roger St C. Smart

Research output: Contribution to journalArticlepeer-review

92 Citations (Scopus)

Abstract

The influence of pH and surface chemical state on rheological behaviour was investigated for variations of silica- and alumina-coated, aluminum-doped titania pigment suspensions. The variation in rheological properties correlates with the change in the pigment surface properties, determined from electrophoresis measurements, atomic concentrations, chemical states and modified Auger parameters derived from X-ray photoelectron spectroscopy (XPS). Pigment suspensions exhibited a maximum yield stress and viscosity at or near the isoelectric point (iep). At a pH where the magnitude of the zeta potential of the titania pigment is high, a low-viscosity, dispersed suspension was obtained. The pH of the maximum yield value of the pigment suspension increases with increasing aluminum hydroxyl group density and decreases with increasing silicon hydroxyl group density. Low-viscosity pigment dispersions were obtained with increasing aluminum surface concentration and further reduced with an increase in the silicon surface concentration. Pigment particle attractions are chiefly dictated by van der Waals forces and heteroaggregation. The pigment aggregate strength therefore depends upon the Hamaker constant of the heterogeneous pigment based on the proportion of the respective surface groups.
Original languageEnglish
Pages (from-to)27-41
Number of pages15
JournalColloids and Surfaces A: Physicochemical and Engineering Aspects
Volume155
Issue number1
DOIs
Publication statusPublished - 15 Sep 1999
Externally publishedYes

Keywords

  • Pigments
  • Rheology
  • Surface chemistry
  • Titania
  • Titanium dioxide

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