Dispersion and rheological properties of ceramic suspensions using linear polyacrylate copolymers with carboxylic groups as superplasticizer

To understand the relationship of molecule structure and dispersion mechanism, the influence of linear polycarboxylate-type superplasticizers on the adsorption properties and rheological behavior of ceramic suspension were carried out in this study. Experiments, measuring the static and dynamic viscosity of different polyelectrolytes and their rheological behavior in concentrated ceramic slurry, were investigated in order to get well-dispersed suspension with high solid content. The results of the viscosity curves indicate that the ability of dispersing slurry mainly depends on the amount of the charge density, polyelectrolyte with more charge density led to better dispersing effect. Meanwhile, the electrokinetic measurements were greatly affected by the surface charge of the particles, which was strongly determined by the number of polymer's adsorption and its charge density. The polymer, sodium poly(acrylic acid-co-maleic anhydride-co-itaconic acid) bearing more charge density in their side chains, can produce a more stable dispersion and fluidity in concentrated suspensions. Moreover, we examined the relationship between the polymer dosage and the bending strength of ceramic bodies.

SAMI is an efficient dispersant to keep stability and rheological of the ceramic slurry, it shows the shear stress versus shear rate at different maximum shear rates (100, 250, 500 s−1) for the tested dispersing agents. The following figure shows that SAMI has the lowest shear stress and a low thixotropy, and the hysteretic area is smaller than others. In addition, all suspensions show a classical positive thixotropy. Shear stress (Pa) versus shear rate (s−1) for particle concentration with 0.3% (w/w) for each polymer.Figure optionsDownload as PowerPoint slideHighlights
► Dispersion ability of three linear polyacrylate salts with different charge density.
► More charge density led to better dispersing ability and stability properties of slurry.
► Polyelectrolyte with more charge density can improve bending strength of bodies.
► Electrostatic interactions have a big effect for rheology and stability of suspension.