Temperature dependence of aging kinetics of hectorite clay suspensions

The aging of salt-free hectorite suspensions with different concentrations (cL = 2.9, 3.2 and 3.5 wt%) stored for 2 days or 4 days was studied by rheology at different temperatures. The evolution of storage and loss moduli G′ and G″ during aging followed aging time–temperature superposition. The temperature dependence of the shift factor aT, which reflected the aging kinetics, was interpreted by the reaction-limited colloidal aggregation (RLCA) mechanism with counterion condensation in calculating the double-layer interaction of the charged clay particles. Temperature dependence of the plateau modulus and yield stress of the suspension aged for 800 s was modeled with the soft glassy rheology (SGR) theory. The estimated noise temperature x indicated that the sample aged at higher temperature corresponded to a deeper quench in the nonergodic state. Under larger amplitude of oscillatory shear, the suspension exhibited a strain rate-frequency superposition (SRFS). The shearing eliminated the effects of aging and heating.

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