Acrylic copolymers and the corresponding siloxane copolymers grafted with cationic and nonionic hydrophiles were used as dispersants to disperse fumed silica in an aqueous solution at different pH values. The dispersing ability was evaluated by viscosity and scanning electron microscopy (SEM) methods. The results showed that the dispersing abilities are functions of the dispersant concentrations and of the pH of the system. By comparing the results of SEM and viscosity methods, it can be concluded that, under comparable conditions, a suspension with a lower viscosity is more homogenously dispersed. It was also found that at pH 2 only CHE and SHE and that at pH 7 only CHE, SHE, and SQHE showed better dispersing ability. At pH 10.5, all the dispersants in this study except CQDEA resulted in a slurry of very low viscosity of 10-20 cP with 15 wt% of silica. Basically, nonionic dispersants CHE and SHE exhibit excellent dispersing ability at different pH values.
All Science Journal Classification (ASJC) codes
- Physical and Theoretical Chemistry
- Polymers and Plastics
- Colloid and Surface Chemistry
- Materials Chemistry