Physical and Chemical properties of CMC
Physical properties
Sodium carboxymethyl cellulose (CMC) an anionic cellulose ethers, the appearance is white or slightly yellow flocculent fiber powder or white powder, odorless, tasteless, non-toxic; soluble in cold water or hot water to form a certain stick degree of transparent solution. Neutral or slightly alkaline solution, insoluble in alcohol, ether, isopropyl alcohol, acetone and other organic solvents, soluble in water 60% ethanol or acetone solution. Hygroscopic, light and heat stability, viscosity decreases with increasing temperature, the solution PH value of 2 to 10 in the stable, PH below 2, solid precipitates, PH value higher than 10 viscosity. Color temperature of 227 ℃, carbonization temperature is 252 ℃, 2% aqueous solution surface tension 71mn / n.
Chemical properties
A carboxymethyl cellulose derivatives substituted with sodium hydroxide to form alkali cellulose, cellulose, and then with chloro-acetic acid reaction. Constitute the glucose units of cellulose has three hydroxyl can be replaced, so the availability of different degrees of substitution products. 1g dry weight per 1mmol carboxymethyl leaders who, in water and dilute acid does not dissolve, but the swelling can be used for ion-exchange chromatography. Carboxymethyl pKa in water of about 4, in 0.5mol / L NaCl in about 3.5, is a weak acid cation exchanger, usually more than pH4 for the separation of neutral and basic proteins. 40% of carboxymethyl substitution for the hydroxyl may form a stable water-soluble high viscosity colloidal solution.