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What is Poly Anionic Cellulose (PAC)?

Poly Anionic Cellulose is a water-soluble, anionic polymer derived from cellulose through chemical modification. It’s created by introducing carboxymethyl groups to the cellulose backbone, making it negatively charged (anionic) and highly versatile. PAC is typically available as a white or off-white powder and comes in different grades based on viscosity and purity (e.g., technical grade for industrial use, high-purity for food/pharma).

Chemical Composition

  • Base Material: Cellulose (a natural polysaccharide from plant cell walls).
  • Modification: Carboxymethylation adds -CH₂COOH groups, increasing solubility and ionic properties.
  • Formula: Generally represented as [C₆H₇O₂(OH)₃₋ₓ(OCH₂COONa)ₓ]ₙ, where “x” is the degree of substitution (DS), typically 0.7–1.2, and “n” is the degree of polymerization.

Key Properties

  1. Water Solubility: Dissolves easily in water, forming clear, viscous solutions.
  2. Viscosity Control: Adjustable based on molecular weight and concentration (low-viscosity PAC-LV or high-viscosity PAC-HV).
  3. Thermal Stability: Resists degradation at high temperatures (useful in drilling).
  4. Salt Tolerance: Effective in saline environments (e.g., seawater-based drilling fluids).
  5. Film-Forming: Creates thin, protective layers (e.g., in drilling muds or coatings).
  6. Biodegradability: Environmentally friendly in many contexts.

Common Applications

  1. Oil Drilling: Viscosifier and fluid loss reducer in drilling muds.
  2. Food Grade: Thickener/stabilizer in products like ice cream or sauces.
  3. Pharmaceuticals: Binder or disintegrant in tablets and suspensions.
  4. Construction: Improves workability and water retention in cement/mortar.
  5. Other Uses: Paper sizing, textile printing, cosmetics (see prior response for details).

Production

  • Process: Cellulose is treated with sodium hydroxide and monochloroacetic acid under controlled conditions to substitute hydroxyl groups with carboxymethyl groups.
  • Grades: Purified for food/pharma (low impurities) or technical-grade for industrial use.

Advantages

  • Non-toxic (in food-grade forms).
  • Cost-effective compared to some synthetic polymers.
  • Versatile across pH ranges and temperatures.

Limitations

  • May degrade in highly acidic conditions.
  • Performance can vary with water hardness or extreme salinity (mitigated by formulation adjustments).