The main indicators to measure the quality of CMC are the degree of substitution (DS) and purity. Generally, the properties of CMC are different when the DS is different; the higher the degree of substitution, the better the solubility, and the better the transparency and stability of the solution. According to reports, the transparency of CMC is better when the degree of substitution is 0.7-1.2, and the viscosity of its aqueous solution is the largest when the pH value is 6-9.
In order to ensure its quality, in addition to the choice of etherifying agent, some factors that affect the degree of substitution and purity must also be considered, such as the dosage relationship between alkali and etherifying agent, etherification time, system water content, temperature, pH value, solution concentration and salts.
Sodium carboxymethyl cellulose is widely used in petroleum, food, medicine, textile, papermaking and other industries, so it is very important to accurately judge its purity, and it is also a measure to ensure its use effect, then, How can we see, smell, touch, and lick to judge its purity?
1. Sodium carboxymethyl cellulose with high purity has extremely high water retention, good light transmittance, and its water retention rate is as high as 97%.
2. Products with high purity will not smell the smell of ammonia, starch and alcohol, but if they are of low purity, they can smell a variety of tastes.
3. The pure sodium carboxymethyl cellulose is fluffy visually, and the bulk density is small, the range is: 0.3-0.4/ml; the fluidity of adulteration is better, the hand feel is heavier, and there is a significant difference with the original appearance.
4. The chloride content of CMC is generally calculated in CL, after the CL content is measured, the NaCl content can be converted into CL%*1.65
There is a certain relationship between CMC content and chloride, but not all, there are impurities such as sodium glycolate. After knowing the purity, the NaCl content can be roughly calculated NaCl%=(100-purity)/1.5
Cl%=(100-purity)/1.5/1.65
Therefore, the tongue-licking product has a strong salty taste, indicating that the purity is not high.
At the same time, high-purity sodium carboxymethyl cellulose is a normal fiber state, while low-purity products are granular. When buying a product, you must learn several simple methods of identification. In addition, you must choose a manufacturer with a good reputation, so that the product quality is more guaranteed.