Catalog NumberHG9003036
CAS Number9003-03-6
CategoryPolymer Surfactants
Use as dispersing agent, emulsifying agent.
Use as thickening agent.
Ammonium Polyacrylate as Dispersant for Ceramic Slurry Processing
Cheng, Chuan Bing, et al. Materials Science Forum. Vol. 816. Trans Tech Publications Ltd, 2015.
Gelcasting is a promising near-net-shape forming technique that has been studied for over two decades for producing structural and functional ceramics. The process involves preparing aqueous ceramic slurry, moulding, in situ polymerization, demoulding, drying, debinding, and sintering. The key to successful gelcasting lies in preparing low-viscosity, concentrated, high-solids-loading aqueous ceramic suspensions with excellent rheological properties. Silicon nitride (Si3N4) powders present particular challenges for aqueous processing due to hydrophobic amine groups (Si-NH2 and Si2NH) on particle surfaces, which severely limit dispersibility, along with soluble high-valence counter-ions that can further destabilize slurries. Ammonium polyacrylate (PAA-NH4) functions as an effective polyelectrolyte dispersant by providing combined steric and electrostatic repulsion between ceramic particles.
Experimental Protocol: Si3N4 powders (mean diameter <0.5 um, 93% alpha-phase) were dispersed in a premix solution with 15 wt% organic monomers (DMAA:MBAM=50:1) and PAA-NH4 as dispersant. pH was adjusted using HCl and NH4OH. The effect of PAA-NH4 concentration and pre-oxidation treatment of Si3N4 powders on slurry rheological properties was systematically investigated through viscosity measurements and zeta potential analysis.
Performance Evaluation: The Si3N4 isoelectric point (IEP) was determined between pH 3 and 4, with maximum particle surface potential achieved at pH 9.5-10.5. PAA-NH4 addition significantly decreased slurry viscosity, with an optimal dispersant dosage of approximately 1.6 wt% of Si3N4 powders. The Si3N4 slurries exhibited pseudoplastic fluid behavior with characteristic shear-thinning properties.
Ammonium Polyacrylate for Colloidal Stabilization in Aqueous Suspensions
Tseng, Wenjea J., et al. Colloids and Surfaces A: Physicochemical and Engineering Aspects 276.1-3 (2006): 34-39.
Indium tin oxide (ITO) thin films are valued for their high optical transparency (>90%) in the visible region and near-metallic electrical conductivity, enabling wide optoelectronic applications. Aqueous colloidal processing using fully densified ITO nanoparticles offers a cost-effective alternative to vacuum-based deposition methods such as sputtering. However, achieving stable dispersions without aggregation remains challenging due to strong van der Waals forces at the nanoscale, potentially leading to porous films with diminished electrical properties.
Experimental Protocol: ITO nanoparticles were dispersed in deionized water with ammonium polyacrylate (NH4PA) at 0.5-2 wt%. Rheological characterizations were performed over shear rates from 10 to approximately 500 s-1. Zeta potential measurements evaluated the electrosteric stabilization mechanism. The maximum solids concentration (phi_max) at which the suspension transitions from liquid-like to solid-like behavior was determined.
Performance Evaluation: A pronounced viscosity reduction exceeding 99% at 100 s-1 was achieved when NH4PA was introduced at 0.5-2 wt%. Zeta potential measurements confirmed preferential NH4PA adsorption on nanoparticle surfaces, providing sufficient electrosteric repulsion. The suspension exhibited Newtonian flow up to approximately 500 s-1, transitioning to shear-thickening at higher rates. The maximum solids concentration was determined as phi_max=0.34, a relatively low value indicating that van der Waals attraction ultimately prevails over all other interparticle forces at critical separations despite the presence of surfactant.
Ammonium Polyacrylate as Binder and Dispersant for Refractory Castables
Ewais, Emad MM, et al. Journal of the European Ceramic Society 30.16 (2010): 3425-3434.
Piezoelectric ceramics such as lead zirconate titanate (PZT) are extensively used in transducers for medical imaging, igniters, and micromotors, owing to high dielectric constant, charge coefficient, and electromechanical coupling coefficient. Conventional PZT fabrication uses non-aqueous solvents and large amounts of organic binders that cause geometry distortion, microstructure defects, and environmental pollution. Water-based gelcasting with ammonium polyacrylate as dispersant and agarose as gelling agent offers a cleaner, more economical alternative with reduced binder burnout and minimal environmental impact.
Experimental Protocol: PZT-5 suspensions (46-48 vol% solids) were prepared in aqueous media using ammonium polyacrylate (PAA-NH4) as dispersant and agarose (0.082-0.19 wt% based on dry solid) for gelation. Gelation was monitored by measuring sample height before and after demoulding. Green density, drying shrinkage, and sintered density at 1250-1285 C were determined. Dielectric and piezoelectric properties of sintered samples were characterized.
Performance Evaluation: Optimal green parts were achieved at 0.082-0.19 wt% agarose, yielding green densities of 52% and 55% before and after drying. Sintered samples at 1250-1285 C reached 99% of theoretical density with only 16.2% shrinkage. The dielectric constant reached 2550 and the longitudinal piezoelectric charge coefficient (d33) reached 680 pC/N, demonstrating that the ammonium polyacrylate/agarose gelcasting system produces high-quality PZT components with excellent electromechanical properties.