Pure sodium carboxymethyl cellulose is white or milky white fibrous powder or granules, odorless and tasteless. It is insoluble in organic solvents such as methanol, ethanol, ether, acetone, chloroform, and benzene, but soluble in water. The degree of substitution is an important factor affecting the water solubility of sodium carboxymethyl cellulose, and the viscosity of sodium carboxymethyl cellulose also has a great influence on the water solubility.
One of the sodium carboxymethyl cellulose properties is hygroscopicity. The equilibrium water content of sodium carboxymethyl cellulose increases with the increase of air humidity and decreases with the increase of temperature. Under the conditions of room temperature and average humidity of 80-85%, the equilibrium moisture content is above 26%, but the product moisture content is lower than 10%, which is lower than the former. As far as its shape is concerned, even if the water content is about 15%, there seems to be no difference in appearance.
However, when the water content reaches more than 20%, the mutual adhesion between the particles can be felt, and the higher the viscosity, the more obvious. For polarized polymer compounds like sodium CMC, the degree of moisture absorption is not only affected by the relative humidity, but also by the amount of polarity. The higher the degree of OS substitution, that is, the greater the polarity number, the stronger the hygroscopicity of sodium carboxymethyl cellulose. In addition, the degree of crystallinity also affects it. The higher the degree of crystallinity, the lower the hygroscopicity.
The properties of sodium carboxymethyl cellulose are compatible. Sodium carboxymethyl cellulose has good compatibility with other kinds of water-soluble glues, softeners and resins. For example, it is compatible with animal glue, dimethoxydimethylurea gel, acacia, pectin, tragacanth, ethylene glycol, sorbitol, glycerin, invert sugar, soluble starch and sodium alginate. The 1% sodium carboxymethyl cellulose solution is compatible with most inorganic salts.