Dispersion state and rheology of hectorite particles in water over a broad range of salt and particle concentrations

作者：Kimura Hiroshi^*; Sakurai Mikito; Sugiyama Taiki; Tsuchida Akira; Okubo Tsuneo; Masuko Toru

来源：Rheologica Acta, 2011, 50(2): 159-168.

DOI：10.1007/s00397-011-0532-7

• Hectorite
• Dispersion state
• Rheology
• Deionization
• Electrical double layer

The relationship between the rheological properties of deionized aqueous suspensions of hectorite particles and the dispersion states of the particles has been studied with a broad range of salt and particle concentrations. The shear viscosity of the hectorite suspensions decreases drastically after exhaustively deionizing the suspensions with ion-exchange resins. By means of DLS measurements, it is clarified that the average size of the flocs of hectorite particles decreases and reaches the Stokes diameter of the individual particle as the degree of deionization advances. This fact strongly supports the idea that the electrical double layer around the hectorite particles expands significantly in the exhaustively deionized state and the particles are well-dispersed individually and do not form a three-dimensional network structure composed of particles, whereas such a network structure forms in the presence of a large amount of salt. In the case of exhaustively deionized state, the suspension forms a glassy state, at high particle fractions. The results show the importance of the electrical double layer that causes a strong repulsive force among the particles on the particle dispersion state, especially in the exhaustive deionization area below 10 (-aEuro parts per thousand 4) M, and on the rheological properties; the hectorite suspension can be considered a Newtonian liquid in the deionized state, but it becomes elastic-solid in the presence of salt above a certain concentration confirmed by normal stress measurements.

• 出版日期2011-2