Abstract
The effects of the concentration of polyethylene glycol (PEG) and NaCl on the gelation kinetics of aqueous Laponite suspensions were investigated. The PEG concentration cp was increased from 0.063wt.% to 1.0wt.%, and the NaCl concentration cs was increased from 3.0mM to 5.0mM. The gelation process was monitored with the small amplitude oscillatory shear (SAOS) rheology. At each NaCl concentration, the time curves of storage and loss moduli G′ and G″ at different PEG concentrations were shifted horizontally to construct a master curve. Master curves for different NaCl concentrations were shifted further into a main master curve. The results were understood in terms of an increase in steric repulsion with increasing cp. A model based on the theory of interaction-limited coagulation was proposed to describe the dependence of the shift factor on the PEG concentration, taking into account of the interactions between particles. The quantitative description of the observed results has been achieved with this model.
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