Impact of Surface Chemistry on Particle Electrostatic Charging and Viscoelasticity of Precipitated Calcium Carbonate Slurries, 1991 Coating Conference Proceedings

The rheology of coating colors is now well recognized to be a function of both particle packing and surface chemical effects. In this paper we explore the complex rheology of precipitated calcium carbonate (PCC) slurries where surface chemistry has been carefully controlled. Surface chemistry was characterized with a combination of surface charge measurements (via a Matec electrokinetic sonic amplitude analyzer) and adsorption calorimetry. Viscoelasticity was assessed with a Bohlin rheometer. We have found that the unique surface chemical features of PCC (namely, the presence of strongly adsorbed calcium ions as interactive sites) determine the nature of the binding configuration of conventional anionic polyelectrolytes to the PCC surface and hence the rheology of the slurry. We further suggest ways in which these unique features may be used to improve the rheology of a PCC-based coating color where particle size distribution (packing) has been chosen to optimize coating structure.