Colloidal properties of synthetic hectorite clay dispersions: I. Rheology

Abstract The rheological properties of aqueous dispersions of Laponite-RD—a synthetic hectorite-type swelling clay—have been studied at low ionic strength ([Na] ∼ 10−3 mole dm−3) with a Weissenberg rheogoniometer. From measurements made under oscillatory shear, the storage, G′, and loss, G″, moduli have been determined in the concentration range 0.03 to 0.10 g ml−1. All these dispersions formed elastic gels on prolonged standing, and the progress and mechanism of gelation has been investigated by kinetic measurements of G′ at different temperatures. It is concluded that the development of elastic behavior which occurs during the gelation process, arises from osmotic swelling and the formation of an equilibrium structure due to electrostatic repulsion between the individual clay microcrystals.