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Aqueous dispersions of colloidal gibbsite platelets: synthesis, characterisation and intrinsic viscosity measurements

1998; Elsevier BV; Volume: 134; Issue: 3 Linguagem: Inglês

10.1016/s0927-7757(97)00224-0

1873-4359

Anieke M. Wierenga, T. A. J. Lenstra, Albert P. Philipse,

Electrostatics and Colloid Interactions

We report preparation and properties of model platelets for the study of rheology and structure formation. The colloids are well-defined, regularly shaped and fairly monodisperse hexagons with an average diameter of 160 nm and a thickness of 13 nm. Various characterisation techniques demonstrate that the particles consist of gibbsite. The isoelectric point of the edges (pH≈7) differs from that on the faces (pH≈10). At pH<4, addition of lithium chloride induces face-to-face aggregation, which causes settling to dense sediments. In the range 7 < pH < 10, low density gels are formed, probably due to the formation of a fractal network of edge-to-face aggregates. For stable gibbsite dispersion, low-shear viscosity measurements yield the intrinsic viscosity [η] = 23 and the Huggins coefficient kH = 0.4.