Cellulose ethers are high molecularweight compounds prepare by replacing hydrogen atoms of hydroxyl groups in the anhydroglucose units of cellulose with alkyl orsubstituted alkyl groups. The commercially main properties of cellulose ethersare determined by their molecular weights, chemical structure and distributionof the substituent groups, the degree ofsubstitution (DS) and a molarsubstitution.
These properties normally contain solubility, viscosity insolution, surface activity, thermoplastic film characteristics and stabilityagainst biodegradation, heat, hydrolysisand oxidation. The viscosity of celluloseether solutions is directly linked withtheir molecular weights. The properties of cellulose ethers are controlled bythe degree of polymerization (DP) and degree of substitution . Examples of mostly used celluloseethers are Methylcellulose (MC),Ethylcellulose (EC), Hydroxyethylcellulose (HEC), Hydroxypropylcellulose (HPC), hydroxypropylmethylcellulose (HPMC),carboxymethylcellulose (CMC) and sodium carboxymethylcellulose (NaCMC) 9. Sodiumcarboxymethylcellulose (NaCMC) is the most widely used cellulose ether,prepared by the reaction of chloroacetic acid and cellulose, water-soluble, large DS range (usually0.
7-1.2), water solubility increases with DS, used in milk products, dressings,jellies, syrups 10. Synthesis of Carboxymethyl CelluloseCellulose is a polymer with anextremely high internal cohesive energy, due to its high content of hydroxyls functions. Consequently, it does notdissolve readily either in common organic solventsor in water. The use of the OH-function of cellulose yield one of the first semi-synthetic polymers (cellulose acetates,nitrates, etc.
). Sodium carboxymethylcelluloseis also a cellulose derivative, produced by the etherification of the hydroxyl group of cellulose macromolecules by monochloroacetic acid (MCA). Sodium carboxymethylcellulose synthesized for thefirst time in 1920, and it is the most used cellulose derivative 11.