According to the degree of substitution of acetyl groups by hydroxyl groups in cellulose, it can be divided into diacetate and triacetate.
Di vinegar is formed by partial hydrolysis of first vinegar, and its degree of esterification is lower than that of tri vinegar. Therefore, the heating performance is not as good as that of the tri-vinegar, the dyeing performance is better than that of the tri-vinegar, and the moisture absorption rate is higher than that of the tri-vinegar.
Triacetate is a type of ester, and its esterification degree is higher without hydrolysis. Therefore, it has strong light and heat resistance, poor dyeing performance, and low moisture absorption rate (also called moisture regain).
In the molecular structure of cellulose acetate, the hydroxyl group on the cellulose glucose ring is replaced by an acetyl group to form an ester bond. The degree of esterification of cellulose diacetate is lower than that of cellulose triacetate due to hydrolysis. In the supramolecular structure of cellulose diacetate, the amorphous area is larger, while the cellulose triacetate has a certain crystalline structure, and the symmetry, regularity and crystallinity of the fiber macromolecules are higher than that of the cellulose diacetate.