MA/AA·Na (Sodium salt of Maleic acid-Acrylic acid copolymer, also known as MA-AA·Na or poly(maleic acid-co-acrylic acid) sodium salt) is a low-molecular-weight polyelectrolyte dispersant and scale inhibitor. It is the neutralized (sodium salt) form of the MA/AA copolymer, commonly used in water treatment, detergents, and industrial applications.
Key Stability Aspects of MA/AA·Na
Thermal Stability
The copolymer exhibits excellent thermal stability, maintaining performance even at high temperatures up to 300°C. This makes it suitable for systems involving elevated heat, such as circulating cooling water, medium/low-pressure boilers, distillation systems, and oilfield applications where high temperatures are common. The sodium salt form retains this high-temperature resistance, with minimal degradation or loss of dispersing/scale-inhibiting properties under prolonged exposure.
Hydrolytic and pH Stability
As a polycarboxylate polymer, MA/AA·Na is generally stable across a wide pH range. The acid form (MA/AA) typically has a pH of 2.0–3.0 (1% solution), while the sodium salt is supplied with a pH of 7.0–9.0 or 8–10 (depending on the degree of neutralization and formulation). It shows good resistance to hydrolysis in both acidic and alkaline conditions, which is beneficial for detergent builders and water treatment in varying pH environments. It also provides pH buffering ability.
Chemical Stability and Compatibility
Good compatibility with other water treatment chemicals, including organic phosphonates (e.g., when used together for synergistic scale inhibition).
Resistant to many common ions and impurities in hard water or industrial systems.
Non-toxic, phosphorus-free (in many formulations), and environmentally friendly with low pollution potential.
Stable in storage when kept in a cool, dry, shady place (shelf life often 12 months for solid forms or 1 year for liquids). Avoid extreme conditions that could cause precipitation or viscosity changes.
Other Stability Notes
Oxidative stability: Performs well in systems with chlorine or other oxidants, though specific data varies by exact molecular weight and composition.
Dispersion stability: Effectively maintains long-term suspension of particles (e.g., carbonates, iron oxides, pigments) due to electrostatic repulsion from carboxylate groups.
In thermal analysis studies of the sodium salt (used as a binder or dispersant), it shows controlled decomposition behavior suitable for high-temperature processes.
Low tendency for decarboxylation or significant molecular weight loss compared to some other polycarboxylates under stress.
Typical Specifications (Varies by Supplier)
Appearance: White to light yellow granular/solid or light yellow to yellow viscous liquid.
Solid Content: ≥90% (solid) or ~40% (liquid).
pH (1% solution): 7.0–9.0 or 8–10.
Solubility: Highly water-soluble.
Compared to related compounds like PESA (fully biodegradable, phosphorus-free) or PBTC (strong chelator with phosphonate group), MA/AA·Na offers a balanced cost-effective profile with strong thermal stability and dispersing power for carbonates and phosphates, but it may have lower biodegradability than PESA.
Overall, MA/AA·Na is valued for its robustness in harsh industrial conditions, particularly where high heat and scale control are required.