ACUSOL 820

• CAS: 75760-37-1
• Catalog Number: ACM75760371
• Category: Main Products

Case Study

Acusol 820 used to study the mechanical properties of coagulated wet particle networks

Hesselbarth, Daniels, et al. Journal of the American Ceramic Society 84.8 (2001): 1689-1695.

Alkali swellable thickeners (ASTs), such as Acusol 820 and Acusol 830, and poly(acrylic acid) homopolymers of various molar masses, have been used as additives to aqueous electrostatically stabilized alumina suspensions. These suspensions have been destabilized by internal enzyme-catalyzed reactions to form viscoelastic solids. The ASTs increase the strength and modulus of the wet green bodies upon coagulation. The effect of their molecular structure on the mechanical properties of the wet particle networks has been studied. At low pH, the ASTs are insoluble small polymer particles that have little effect on the low viscosity of high solids content suspensions. After shifting the pH towards the isoelectric point of a-AlO, the suspensions coagulate and the AST polymer particles swell, thereby increasing the compressive strength and modulus of the wet green bodies of alumina particles. The presence of small amounts of ASTs (0.4 wt%, based on solid loading) leads to a 10-fold increase in the strength of the wet green bodies.
Effect of ionic strength on the size of individual Acusol 830 and Acusol 820 particles at pH 9, measured by dynamic light scattering. At low ionic strength, the particle sizes of Acusol 830 and Acusol 820 are nearly identical (700 nm); however, at high ionic strength, the diameter of the associated Acusol 820 is much smaller than that of Acusol 830. For fully ionized gels, electrostatic repulsion takes precedence over hydrophobic association. The addition of salt screens intermolecular interactions and results in increased intramolecular association of hydrophobic molecules, which has a tendency to reduce the size of the polymer coils.

Acusol 820 was used to improve the colloidal stability of sepiolite suspensions

Alves, Luís, et al. Minerals 10.9 (2020): 779.

The effects of four dispersants (sodium polyphosphate, hydrophobically modified poly(sodium acrylate) (HM-PAA consisting of Acusol 820), sodium carboxymethylcellulose (CMC) and sodium alginate) and three different dispersing devices (magnetic stirring, ultrasound and high-speed shear) on the dispersion state of water-based sepiolite suspensions at low concentrations were evaluated. The capacity of each dispersant and device, as well as the effect of the pH of the suspension, were studied with the aim of improving the deagglomeration and formation of stable suspensions, i.e., without phase separation for at least 90 days (by visual inspection), which is essential to significantly improve the properties of fibrous clays and expand their applications, for example, in cellulose nanofiber/clay composite formulations, allowing for the thorough mixing of the individual components of the matrix and filler.
Hydrophobically modified sodium polyacrylate (HM-PAA) (Acusol 820, 30% active emulsion polymer composed of 40% methacrylic acid, 50% ethyl acrylate and 10% stearyloxyethyl acrylate. The results obtained with polyacrylate (HM-PAA) as a dispersant and stabilizer were quite unexpected. It was found that this polymer can have good performance as a dispersant for sepiolite, but is less effective as a stabilizer for the suspension. The pKa of the polymer is higher than the pKa of the other three dispersants studied, about 5.8; secondly, the polymer has a hydrophobic modification, which results in a change in the expansion of the polymer chains.