Polyacrylamide and Sodium polyacrylate
By Polyacrylamide factory–Xinqi
The main differences between sodium polyacrylate and polyacrylamide lie in their chemical structure, ionic properties, and application areas. Sodium polyacrylate is an anionic surfactant, while polyacrylamide can exhibit anionic, cationic, or nonionic properties, depending on the type. They are suitable for applications such as dispersing and scale inhibition and flocculation and thickening, respectively.
Differences in Chemical Structure and Ionic Properties
Chemical Composition
Sodium polyacrylate: Produced by polymerization of acrylic acid followed by neutralization, its chemical formula is (C₃H₃NaO₂)ₙ. Its molecular structure contains sodium carboxylate groups (-COONa), making it a polymer electrolyte.
Polyacrylamide (PAM): Produced by polymerization of acrylamide monomers, its chemical formula is (C₃H₅NO)ₙ. Its backbone contains amide groups (-CONH₂), making it a linear polymer.
Ionic Properties
Sodium polyacrylate is an anionic surfactant, containing only negatively charged groups.
Polyacrylamide can be classified as anionic, cationic, nonionic, and zwitterionic based on its modification method, offering greater application flexibility.
Physical Properties and Functional Characteristics
Solubility and Viscosity
Sodium polyacrylate forms an extremely high-viscosity liquid (a 0.5% solution has a viscosity of approximately 1 Pa·s) when dissolved in water. It is stable to temperature fluctuations, but will precipitate when the pH is < 4.
Polyacrylamide has a relatively low viscosity when dissolved, but exhibits excellent flocculation properties, making it particularly suitable for use in neutral to alkaline environments.
Stability and Safety
Sodium polyacrylate readily forms a gel precipitate when exposed to divalent or higher-valent metal ions, and the powder may irritate the eyes and skin.
Polyacrylamide may hydrolyze at high temperatures or in strong acidic conditions, and some types are biotoxic, so use with caution.
Application Comparison
Sodium polyacrylate
Water treatment: Used as a scale inhibitor and dispersant to prevent scale buildup in pipes.
Food industry: Used as a dough conditioner to improve food elasticity and preserve freshness.
Cosmetics: Used as a thickener and moisturizer, commonly found in lotions and gels.
Polyacrylamide
- Wastewater Treatment: Anionic types are used for suspended particle flocculation, while cationic types are suitable for sludge dewatering.
- Oil Extraction: Improves oil recovery efficiency by reducing fluid friction.
- Paper Industry: Used as a paper strengthening agent and wastewater treatment agent.
