The rheological properties and characterization of bentonite dispersions in the presence of non-ionic polymer PEG

The effect of poly(ethylene glycol) on the flow behavior of Ca-bentonite and soda activated bentonite dispersions was characterized by the plastic viscosity, the relative viscosity and the yield values. In the range 0.025–12.5 mol/m3, poly(ethylene glycol) (PEG400, PEG3000, PEG8000) was added to bentonite-water systems in different concentrations. Three layered phases with different basal spacings for each Ca- and Na-bentonites were obtained, as shown by XRD studies. The maximum swelling had a basal spacing at 1.82 nm for both PEG400 containing Ca- and Na-bentonites. In addition, expanded basal spacings are displayed at 1.91 nm for Ca- and 2.08 nm for PEG8000 containing Na-bentonites. After the PEG addition, some significant changes in rheological properties were observed; corresponds changes were also found during XRD and IR studies. The results are interpreted according to the type of bentonites, molecular weight of PEG and their concentrations.