Carboxy methyl Cellulose - Sodium CMC

Grades

  • Sodium CMC IVH6-3
  • Sodium CMC FVH6-3
  • Sodium CMC FVH6-5
  • Sodium CMC 7H9

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Carboxymethylcellulose is an anionic, linear, water-soluble polymer that can exist either as the free acid or its sodium salt or mixtures thereof. The sodium salt is the most common for the food use, as the free acid form is insoluble in water. Carboxymethyl group has an acid function meaning CMC is an anionic polyelectrolyte.
CMC has many interesting properties when dissolved in aqueous solutions but this will depend on CMC grade & solution behavior.
In United States, the term “cellulose gum” is often used for food grade CMC.
CMC is assayed by determining the sodium chloride and sodium glycolate percentages.
CMC was initially developed in Germany as a gelatin substitute. The real drive for its commercial usage was the discovery in 1935 that CMC could improve the efficacy of laundry detergents.

The rate at which CMC dissolves depends primarily on its particle size. Coarse CMC give improved dispersibility but dissolve more slowly. Where rapid hydration in solution is needed, finer grinds are best. Finely ground material dissolves faster than coarser grades. The rate of dissolution also increases with increasing substitution and decreasing molecular weight, ie, viscosity.

High molecular weight grades of CMC have viscosities as high as 12,000 mPa.s (=cP) at 1% solids(as recorded on a Brookfield LVT Viscometer at 30 rpm). Lower molecular weight CMCs have viscosities in water as low as 50 mPa.s(=cP) at 4% solids.

Low viscosity CMC is prepared by aging the shredded alkali cellulose & by using chemical oxidants.



Cellulose Ether
( HEC, HPMC, MHEC, MC)

2% Aqueous Solution NDJ-1

2% Aqueous Solution Brookfield

60000

30000

75000

35000

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45000

100000

45000

150000

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65000

 

CMC is soluble in hot and cold water. CMC is not soluble in organic solvents, but dissolves in mixture of water and water miscible solvents such as ethanol or acetone. Low viscosity CMCs are more tolerant of higher level of organic solvents.
The water solubility is achieved through introducing carboxymethyl groups along the cellulose chain, which makes hydration of the molecule possible.
Solutions may be pseudoplastic or thixotropic depending on molecular weight, DS, and manufacturing process. High molecular weight, low DS CMCs tend to be more thixotropic.

Aqueous solutions of CMCs are viscosity stable at ambient temperature over a wide range of pH. In general, maximum solution viscosity and best stability are obtained at pH 7.0-9.0. Above pH 10.0, a slight viscosity decrease is observed. As pH is lowered below 4.0, viscosity may first increase and then decrease as intermolecular associations among free acid groups start affecting solubility.

Monovalent cations are compatible with CMC and have little effect on aqueous solution properties when added in moderate amount. An exception in silver ion, which precipitates CMC. Divalent cations show border line behavior. Trivalent cations form insoluble salts or gels. The effects vary with specific cation and counter ion, pH,DS, and manner in which CMC and salt are brought into contact. High DS (0.9-1.2) CMCs are more tolerant of monovalent salts than lower DS types, and CMC in solutions tolerates higher quantity of added salts than dry CMC added to brine solution.

CMC is compatible with most water soluble non-ionic gums over wide range of concentractions. When a solution of CMC is blended with solution of non-ionic polymer such as HEC or HPC, a synergistic effect on viscosity is usually observed. Such blends produced solution viscosity considerably higher than would ordinarily be expected. This effect is reduced if other electrolytes are present in the system.

25 kgs HDPE bags with PP liner inside.