Influence of the molecular structure of a polymer dispersant on concentrated SiC aqueous suspensions

To analyze the effect of the molecular structure of a polymer dispersant on aggregation and the dispersion behavior of silicon carbide particles ill a concentrated aqueous suspension, polymer dispersants with different hydrophilic to hydrophobic ratios, m:n = 30:70, 50:50, 75:25, were added silicon carbide suspensions. The dispersant polymers were synthesized from an ammonium salt of acrylic acid and styrene, or from an acrylic methyl monomer. The average molecular weight of each polymer was fixed at 10,000 g/mol. For the copolymer of acrylic acid and styrene, the optimum ratio to minimize suspension viscosity was determined at m:n = 50:50. With this polymer dispersant, the suspension viscosity was lower than with a commercial dispersant for silicon carbide. For the copolymer of acrylic acid and acrylic methyl, the suspension viscosity decreased with increasing hydrophobic group ratio. Based on these results, the adsorption structure and mechanism of dispersion for each polymer dispersant are discussed.