Here we briefly introduce the chemical properties of various fabric fibers as follows.
01
Cotton fiber
Cotton fiber fabric is extremely unstable under the action of inorganic acid. The acid can break and hydrolyze cellulose macromolecules, resulting in a significant decrease in fiber strength. The strength of the acid is different (sulfuric acid, hydrochloric acid, nitric acid are strong acids, acetic acid, formic acid, etc. are weak acids), the concentration and temperature are different, and the degree of hydrolysis of cotton fibers is also different.
Cotton fiber fabric has excellent stability to dilute alkali at room temperature. The so-called mercerization treatment is carried out by taking advantage of this chemical characteristic of cotton fiber: at room temperature, cellulose interacts with alkali The cotton fibers expand radially and shrink slightly in length. At the same time, the surface of the fiber shows a silky luster.
Cotton fibers can be bleached with various oxidants. Such as hydrogen peroxide, sodium hypochlorite, etc., but you must still pay attention to the proper control and use, otherwise it will also cause the fiber strength to deteriorate. Excessive bleaching will not only cause oxidative cracking of fibers, but may also cause fabrics that are too white to oxidize and turn yellow.
02
Hemp fiber
The chemical properties of hemp fiber are similar to those of cotton fiber, and it has certain stability to alkali but not acid resistance. Others, such as antioxidant effects and light resistance, are basically the same as those of cotton fibers.
03
Silk fiber
Silk fabric has good stability to acid but is worse than wool. Concentrated acid can hydrolyze the silk fibroin in silk, and the hydrolysis will become more severe as the acid concentration increases, the temperature increases, and the treatment time increases.
Although silk fabrics are not as sensitive to low-temperature dilute alkali solutions as wool, the luster and feel of silk fabrics will deteriorate under alkaline conditions. Therefore, neutral materials should be used as much as possible when cleaning and maintaining silk fabrics.
Silk fibers react strongly to oxidants. The silk fibroin in the silk fiber can be completely decomposed after being treated with high-temperature hydrogen peroxide for a long time. Chlorine-containing bleach can severely damage silk, so silk fabrics must not be bleached with chlorine.
Silk fabrics are commonly bleached with reducing agents, such as sodium bisulfite, insurance powder, etc. But attention should also be paid to controlling factors such as concentration, temperature and time.
Silk fabrics have the worst light resistance among natural fibers, so they should not be exposed to sunlight.
04
Wool fiber
Wool has a certain stability to acid. Dilute acid will hardly cause damage to wool, but concentrated acid, high temperature, and long-term treatment will also cause the strength of the wool fiber to deteriorate. Treating woolen fabrics with acid can increase their color fastness and color brightness.
Alkali damage to wool fibers is very obvious. 3%-5% boiling caustic soda solution can completely dissolve wool. Wool fibers will shrink when exposed to external forces in cold dilute alkali solutions. Therefore, do not use alkaline detergents when washing wool fiber fabrics.
Oxidants will reduce the strength of wool fibers and increase their solubility in alkaline solutions. Therefore, in general, use oxidants to treat wool fibers with caution. Chlorine causes severe damage to wool fibers. It greatly reduces the strength of wool, so wool fibers cannot be treated with chlorine-containing bleach.
Like silk fibers, the ideal bleaching material for wool fibers is a reducing agent, which causes little damage to the fibers. However, it tends to turn yellow after being exposed to air for a long time. The commonly used reducing bleaching agent for wool fibers is bleaching powder. However, attention should also be paid to controlling the time, temperature and concentration of treatment.
05
Viscose fiber
Because the composition of viscose fiber is similar to that of cotton fiber, many of its properties are similar to cotton. They are both alkali-resistant and acid-resistant. However, its alkali resistance is not as good as cotton fiber, and its ability to resist wrinkles and deformation is far less than that of cotton fiber. In addition, since viscose fiber is spun from natural fiber materials through a series of chemical treatments, although it is insoluble in general solvents, it is soluble in special solutions such as cuprammonium solution and copper ethylenediamine solution.
06
Polyester fiber
Polyester fiber is resistant to acids and weak alkali, and is stable to various oxidants and reducing agents. It is insoluble in general solvents but soluble in hot m-cresol, o-chlorophenol, nitrobenzene, dimethylformamide, and 40℃ in a mixture of phenol and tetrachlorethylene. Polyester fiber has excellent light resistance. Although its fiber strength decreases to varying degrees under sunlight, its light resistance is second only to acrylic fiber among synthetic fibers.
07
Cotton fiber
The acid resistance of cotton fiber is not as good as that of polyester. It will be partially decomposed in concentrated hydrochloric acid, concentrated nitric acid, and concentrated sulfuric acid solutions, and its strength will decrease. However, its alkali resistance is better than polyester. It not only has good stability against general alkaline washing materials, but its fiber strength will basically not change even in concentrated caustic soda solution or concentrated ammonia solution. However, when exposed to sunlight, the color of cotton fiber will turn yellow and its strength will decrease. Therefore, its light resistance is poor among synthetic fibers. Cotton fiber is insoluble in common solvents, but is soluble in phenol solutions such as phenol and m-chlorophenol and concentrated formic acid.
08
Acrylic fiber
Acrylic fiber has high stability to acid and is resistant to 65% concentrated sulfuric acid.The hygroscopicity generally has a low moisture absorption rate, so it does not swell or shrink when exposed to water, and it is not prone to shrinkage and deformation when washed with water. It has good washing and wearability. However, it is precisely because of their low moisture absorption that they are prone to static electricity. It is prone to phenomena such as dust absorption around the body, failure to dissipate heat, and melting holes when encountering sparks.
In addition, the textile materials used in clothing have a certain degree of shrinkage. In addition to being affected by the characteristics of the fiber itself, it is also affected by the spinning, weaving, dyeing and finishing processes of clothing materials. related to the production process.
These clothing materials are subject to a certain amount of mechanical stretching during the production process. These mechanical stretching forces make the yarn and textiles more or less elongated, thus forming a potential shrinkage stress. This potential shrinkage stress will cause all or part of the elongated part to shrink back after the clothing material absorbs moisture, causing the fabric to shrink.
Generally, the radial shrinkage of textiles is greater than the weft direction, and the stronger the hygroscopicity, the greater the shrinkage rate, and the worse the hygroscopicity, the smaller the shrinkage rate.
Since clothing materials made of different fibers have different shrinkage rates, when cleaning and maintaining clothing, and even when sewing clothing, it is necessary to fully consider the shrinkage problem of clothing materials in order to take appropriate measures. Measures to prevent clothing from deforming or shrinking.
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