Carboxymethylcellulose (CMC) is an anionic, water-soluble cellulose derivative. Solubility of CMC depends on the DP as well as the degree of substitution and the uniformity of the substitution distribution. Water solubility of CMC would increase with decreased DP and increased carboxymethyl substitution and substitution uniformity. The viscosity of the solution increases with increasing DP and increasing concentration.
CMC is soluble in water at any temperature. Because of its highly hygroscopic nature, CMC hydrates rapidly. Rapid hydration may cause agglomeration and lump formation when the CMC powder is introduced into water. Lump creation can be eliminated by applying high agitation while the powder is added into the water or preblending the CMC powder with other dry ingredients such as sugar before adding into water.
The production of carboxy methyl cellulose in commercial quantity is in a two-step process namely;
· Suspension of cellulose in an alkaline medium which helps in opening the cellulose chains and pave the way to water entrance.
· Thereafter the cellulose can then react with sodium monochloroacetate to give sodium carboxy methyl cellulose.
Functionality of Carboxy methyl cellulose
Carboxy methyl cellulose has several functions depending on the following:
· Its amount and homogeneity of the substitution of sodium ions
· Length of Carboxy methyl cellulose chain
· The backbone of cellulose
For instance, carboxy methyl cellulose with homogeneity substituent will enhance smooth flow potential as well as function well in icing.
Whereas carboxy methyl cellulose with non-homogeneity replacement species is known as thixotropic, it forms a firm gel that turns extra molten when disturbs and improved the gel with time.
Applications Of Carboxy Methyl Cellulose
Construction Industry
CMC is used in most of the compositions of cement and building materials because it acts as a stabilizer and hydrophilic agent. It improves the dispersion of sand in the cement, and intensifies its adhesive action. It is also used as glue in upholstery.
Detergents
The detergent industry is the largest consumer of CMC. Technical grade CMC compositions are most often used for soaps and detergents. CMC acts as an inhibitor of the redeposition of grease in the fabric after it has been removed by the detergent.
Adhesives
CMC is added to various compositions of glues and adhesives that are used for almost any material. It is widely used in the leather industry. Adhesives that join wood to other wood have been effectively made by combining CMC with starch and phenol formaldehyde.
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