Temperature Dependence For Introduction Adsorption of Carboxy-Methylcellulose on Clay, 1996 Coating Conference Proceedings

Adsorbed and non-adsorbed water soluble polymers markedly affect the rheology and structure of coating color. The aim of this work was to clarify the impact of temperature on the CMC adsorption on clay and its effect on the rheology and dewatering of coating color. The results indicated that at the same charge density, the adsorption of CMC increased with increasing molecular weight and addition. The clay surface was saturated by CMC A Mw 43000 g/mol) and B (Mw 66000 g/mol) at an approximate addition of 1.0 pph, whereas the clay surface was not saturated by CMC C (Mw 83000 g/mol) even with addition of 1.4 pph. The amount of CMC adsorbed on clay decreased with increasing temperature regardless of the molecular weight. However, the difference in the adsorbed amount at the low and high temperature diminished when the molecular weight was changed from low to high. The CMC molecules at higher temperature were less extended in the water phase, which was shown by the reduction in mean radius gyration of the CMC molecules. The results also showed that Na+ was the main counterion in clay based coating colors. The presence of S/B latex did not affect the adsorption of CMC on clay. The high shear viscosity and water retention of coating color decreased with increasing temperature.