Rheology of highly filled dispersions of oxide zinc particles in polymer-containing media including Lewis acids and bases

Sedimentation and dynamic structural stability of moderately concentrated a nd concentrated ZnO dispersions in nonaqueous media with different donor-ac ceptor functions, including a polymeric stabilizing substance [poly(methyl methacrylate)], were studied. It was shown that, as the degree of a system filling with ZnO increases, the rate of sedimentation reduces when the liqu ids are Lewis acids, and rises when these liquids are Lewis bases. This phe nomenon is related to the different strength of a forming thixotropic coagu lation carcass. The reason for stronger ZnO structures in acidic liquids is the different degree of interaction by the acid-base mechanism at the part icle-solvent and polymer-solvent interfaces. Binding forces between two agg regates composed of ZnO particles in different media, which correlate with the dispersion rheological parameters, were calculated on the basis of visc ometric data. The data obtained indicate the importance of interfacial spec ific (acid-base) interactions for controlling structure-related mechanical properties of disperse systems.