Effect of Addition of Polymer on the Rheology and Electrokinetic Features of Laponite RD Aqueous Dispersions

Rheological properties and zeta potential were investigated for 1% Laponite RD aqueous dispersions with different contents of poly(ethylene glycol). At low concentrations of polymer (< 1%), the clay dispersions are stable, whereas an unstable liquid phase appears above 2% polymer. The samples present a Newtonian behavior, showing more viscous than elastic response. The viscoelastic moduli are influenced by the polymer content and temperature. The longest relaxation time presents a maximum at 2% poly(ethylene glycol), when the surface of the clay particles is saturated with polymer. Zeta potential decreases significantly as the polymer chains cover the surface of the particles. The flow activation energy depends on polymer concentration, its values being estimated between (15.64 and 26.89) kJ center dot mol(-1).