some features of Cellulose acetate
Classification of acetate fibers
According to the degree of substitution of hydroxyl groups in cellulose, it can be divided into diacetate fibers and triacetate fibers.
Diacetate is a type 1 vinegar formed by partial hydrolysis, and its esterification degree is lower than that of triacetate. Therefore, the heating performance is less than three vinegar, the dyeing performance is better than three vinegar, the moisture absorption rate is higher than three vinegar.
Trivinegar is a type 1 vinegar ester, which is not hydrolyzed and has high esterification degree. Therefore, light resistance, heat resistance, poor dyeing performance and low moisture absorption rate (also known as moisture regain).
In the molecular structure of acetic acid fiber, the hydroxyl group on cellulose glucose ring is replaced by acetyl group to form ester bond, and the esterification degree of diacetate fiber is lower than that of triacetate fiber due to hydrolysis. Diacetate fiber supramolecular structure of amorphous area is larger, and triacetate has certain crystalline structure, and the symmetry of macromolecular, regularity and crystallinity were higher than diacetate fiber.
The structure of acetate fibers
The surface of longitudinal fiber is smooth and uniform with obvious groove. It can be seen from the shape of its cross section that the fiber has no core structure and is in the shape of alfalfa leaf.
Properties of acetate fibers
1. Alkali resistance
The weak alkaline agent did not damage the acetate fiber, and the fiber weight loss rate was small. When it comes to strong alkali, especially diacetate fiber, deacetylation is easy to occur, resulting in weight loss, and strength and modulus are also decreased. Therefore, the pH value of the solution treated with acetate fiber should not exceed 7.0. Under standard washing conditions, it has strong anti-chlorine bleaching performance, and can also be used for dry cleaning of tetrachloroethylene.
2. Organic solvent resistance
Acetate fibers dissolve completely in acetone, DMF, and glacial acetic acid, but not in ethanol and tetrachloroethylene. According to these characteristics, acetone can be used as the spinning solvent of acetic acid fiber, and the vinegar fiber fabric can be dry-cleaned with tetrachloroethylene.
3. Acid resistance
The acid resistance stability of acetic acid fiber is good. The common sulfuric acid, hydrochloric acid and nitric acid will not affect the strength, gloss and elongation of the fiber within a certain concentration range. But it can dissolve in concentrated sulfuric acid, concentrated hydrochloric acid and concentrated nitric acid
Acetate from cellulose, but in the process of esterification, there was a lot of polar hydroxyl on the cellulose glucose ring part replaced by acetyl ester, therefore, commonly used dyes for cellulose acetate cellulose fibre dyeing almost no affinity, it is difficult to dye. The most suitable dyes for acetate fibers are disperse dyes with low molecular weight and similar dyeing speed.
Acetic acid fiber or fabric dyed with disperse dyes has bright color and bright color, good even-dyeing effect, high dye absorption rate, high color fastness and complete chromatogram.