Effect of D-sorbitol on Rheology of Aqueous Alumina Suspensions with Poly(Acrylic Acid)

Effect of D-sorbitol addition on rheological properties of aqueous alumina suspensions dispersed with poly(acrylic acid)(PAA) was investigated.The results showed that for the aqueous alumina suspensions with 30vol%-40vol% solids loadings,small amount of D-sorbitol can significantly enhance the stability of alumina suspen-sions with PAA at pH=9.0.When the total amount of dispersant was 0.5wt% and the concentration of D-sorbitol was 20%,the viscosity of suspensions was the lowest.In addition,the suspensions dispersed with binary dispersant were less sensitive to ionic strength than the suspensions containing just the PAA.The role of PAA and D-sorbitol in the alumina suspensions was characterized by FTIR spectroscope.Based on the rheology and FTIR measurements,a schematic model was established to depict the mechanism for the effect of D-sorbitol in the presence of PAA.D-Sorbitol was absorbed both on alumina surface and the absorbed PAA,leading to an enhanced steric hindrance thus resulting better stability of the suspensions.