Effect of the adsorption of polyvinyl alcohol on the rheology and stability of clay suspensions

A sedimentation study of suspensions of attapulgite clay in aqueous solutions of polyvinyl alcohol (PVOH) as well as in water was conducted. The results demonstrate that PVOH can be used to control the stability of clay suspensions with respect to sedimentation. While the settling of solid particulates is significantly hindered by the formation of a network structure of clay particles, the adsorption of PVOH disrupts this structure and promotes the settling of solids. The latter effect also serves to lower the system viscosity or permit an increase of solid loading for the same viscosity level; this was quantitatively examined. The results indicate that solid volume fraction, polymer concentration, and polymer molecular weight can be adjusted to yield any desired system rheology and sedimentation stability.