Effect of the molecular weight of a non-ionic polymer on the rheologic properties of Na-activated bentonitic clay

The control of the rheological properties of clay-water systems is important not only from a technological point of view, but also from a scientific one. The effect of a non-ionic polymer, polyethylene glycol, on the rheological properties of a Na-activated bentonite dispersion for two different molecular weight polymers PEG3000 and PEG8000 was analysed. PEG was added to the bentonite dispersion in concentrations ranging between 10 -6 and 10 -2 mole/L. The rheological behavior of bentonite dispersions was obtained by shear stress-shear rate measurements using shear rate ranging between 0 and 350 s -1 . The results were explained considering the molecular weight, concentration of polymer, and particle interactions. The results are explained in terms of flocculation and the partial reversibility of the flocculated structure.