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. It 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 takes advantage of this chemical characteristic of cotton fiber: at room temperature, cellulose and The alkali action causes the cotton fibers to 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 and cotton fiber Similarly, 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 acid resistance Stable but worse than Mao. 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.
The light resistance of silk fabrics is the worst among natural fibers, so it should not be exposed to sunlight.
04 Wool fiber
Wool has a certain stability to acid , dilute acid will cause almost no 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.
The damage of alkali to wool fiber is very obvious. 3%-5% boiling caustic soda solution can completely dissolve the 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
Due to the composition of viscose fiber and Cotton fiber is similar, so 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 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 acid and weak alkali. Various oxidants and reducing agents are very stable. They are insoluble in general solvents but soluble in hot mixtures of m-cresol, o-chlorophenol, nitrobenzene, dimethylformamide, phenol and tetrachlorethylene at 40°C. . 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 Nylon fiber
The acid resistance of nylon is not as good as that of polyester. Concentrated hydrochloric acid, concentrated nitric acid, and concentrated sulfuric acid solutions will be partially decomposed and their 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 a high resistance to acid Stability, its strength remains basically unchanged in 65% concentrated sulfuric acid or 45% nitric acid solution, but its alkali resistance is poor. When treated with alkali, it will turn yellow and the strength will decrease. The higher the alkali concentration, the longer the treatment time. The longer, the more serious the damage. Acrylic fiber has good stability to oxidants and general organic solvents (such as benzene, carbon tetrachloride, tetrachlorethylene, etc.), but is soluble in hot dimethylformamide and dimethyl sulfoxide.�In solvent. Acrylic fiber has the best light resistance among all clothing fibers, so it is often used as outdoor clothing fabrics.
09 Spandex fiber
The chemical properties of spandex are relatively stable. There is basically no change in various acidic, alkaline and other chemical solvents, but it is easily dissolved in hot alkali solution and dissolved or expanded in warm dimethylformamide solution. Its light resistance is not as good as that of acrylic fiber. Its fiber strength gradually decreases and its color changes under long-term sunlight exposure.
10 vinylon fiber
Vinyl fiber is resistant to acid, alkali and Various chemicals are relatively stable to various chemical substances, and their light resistance is also very good, second only to acrylic fiber. Vinyl swells or decomposes in concentrated acid. It dissolves or swells in cresol and concentrated formic acid, but is insoluble in general solvents.
11 Polypropylene fiber
Polypropylene has good chemical stability. It is acid-resistant and alkali-resistant, and is also very stable to various oxidants. However, the light resistance of polypropylene fiber is very poor. After being exposed to sunlight, its strength and speed will decrease, and significant aging will occur. Polypropylene is insoluble in common solvents such as ethanol, acetone, and ether, but expands and slowly dissolves in tetrachlorethylene, carbon tetrachloride, and high-temperature benzene solutions.
The effect of water on common fibers
During the washing process, water It has an impact on the strength and various physical properties of clothing fibers. Different types of clothes use different fiber materials. There are also great differences in the strength and physical properties of fibers with different properties when exposed to water. For example, the tensile strength of some fibers decreases when exposed to water: wool and mulberry fibers decrease by about 14%, and viscose fibers decrease by up to 53%; while the tensile strength of some fibers increases when exposed to water:
Cotton fiber is increased by 2%, and hemp fiber is increased by 5%. In addition, after the fibers are wetted by water, their stretch properties also change greatly. For example, mulberry silk stretches by 46%, viscose fiber stretches by 35%, hemp fiber stretches by 22%, wool fiber stretches by 12%, and only cotton fiber The change is small, only 4% elongation. For this reason, understanding these changes and mastering the rules of performance changes of different fiber materials when exposed to water are the basis for ensuring the quality of clothing cleaning. The changes of common fabric fibers when exposed to water are shown in the table:
01 Cotton fiber
Cotton fiber swells when exposed to water, and its elongation is about 4%. Therefore, the volume of cotton fabric increases in water than when it is dry, and the wet strength is slightly higher than that in dry state, about 2%. This is It is more beneficial to washing. Cotton fiber fabrics have a high moisture regain rate, are comfortable to wear and soft to the touch. However, the high moisture absorption of cotton fiber fabrics also creates conditions for the growth and reproduction of microorganisms. The strength of cellulose destroyed by microorganisms decreases and its stability to alkali is also great. discount.
02 Hemp fiber
Hemp fiber swells when exposed to water and increases its strength , but the elasticity changes too much (about 22% elongation), and it will be deformed if you are not careful during the washing process. Its waterproof and corrosion resistance is better than cotton, and it is not susceptible to microorganisms.
03 Silk fiber
Silk fiber not only has strength after contact with water Decrease, and because the friction between fibers is small and the mutual consolidation is unstable, it should not be rubbed too finely when washing, but should be washed in large quantities. Otherwise, it will not only easily deform, but also cause damage.
Silk fiber has good moisture absorption properties and is comfortable to wear. However, tussah silk is prone to water stains, so you should try your best to avoid splashing water droplets when wearing it.
04 Wool fiber
Wool fiber swells when exposed to water and has tensile strength The strength decreases (about 14%), and under the rubbing action of external force, the fibers become entangled with each other and the felt becomes closer, resulting in a decrease in the length of the wool fabric and an increase in the thickness and density of the fabric. Produce obvious shrinkage and deformation. Moreover, wool fiber is quite sensitive to alkali. However, most current water-based washing materials are alkaline, so wool fiber fabrics should be avoided as much as possible. Wool fiber has good hygroscopicity. Even if the moisture content is as high as 30%, it does not feel wet to the touch. Therefore, wool fiber fabrics should be kept clean and dry before collection and storage to avoid microbial erosion.
05 Viscose fabric
This type of fabric expands rapidly when exposed to water , becomes thick and hard, and the strength is only about 50% of that when dry. Therefore, it is not advisable to rub the viscose fabric heavily when washing. It has good hygroscopicity and is comfortable to wear, but it is prone to wrinkles and deformation, and its shape retention performance is poor.
06 Synthetic fibers
Commonly consumed synthetic fibers generally have low moisture absorption rates , so it does not swell or shrink when exposed to water, and is not prone to shrinkage or 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 related to the spinning, weaving, dyeing and finishing of clothing materials. and other processes related to the production process.
These clothing materials are subject to certain mechanical stretching during the production process. These mechanical stretching forces make the yarn Threads and textiles are more or less elongated, creating an underlying 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, and the hygroscopicity The worse it is, 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 When doing so, it is necessary to fully consider the shrinkage problem of clothing materials so that corresponding measures can be taken to prevent the clothing from deforming and shrinking.
�After absorbing moisture, all or part of the elongated part will shrink back, 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, and the hygroscopicity The worse it is, 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 When doing so, it is necessary to fully consider the shrinkage problem of clothing materials so that corresponding measures can be taken to prevent the clothing from deforming and shrinking. </p
