Overview Of Textile Fibers

Cloth fiber is a soft, thin and long material with spinnability. For fabrics, the ratio of length to diameter should generally be greater than 1000:1. As a fabric fiber, it should also have good physical and mechanical properties, such as definite strength, elasticity and better chemical stability. In nature, cotton, wool, silk, and linen are ideal natural fabric fibers. In addition, chemical fibers manufactured by chemical methods have occupied an important position in fabric fibers. They can be divided into two categories: renewable fibers and synthetic fibers. Regenerated fiber includes regenerated cellulose fiber (viscose, cupra, Fuqiang, Tencel fiber, etc.), cellulose ester (acetate fiber), and regenerated protein fiber (casein fiber, soybean protein fiber, etc.). Synthetic fibers include nylon, polyester, polyacrylonitrile, vinylon, polypropylene, chlorine, spandex, etc. With the advancement of science and technology, the varieties of these fibers are constantly expanding, and researchers are developing new types of regenerated fibers and synthetic fibers.

　　The basic components of all fabric fibers are polymer compounds, including natural polymer compounds (cellulose, protein) and synthetic polymer compounds. The synthetic polymer compounds are named according to the names of the raw materials used, and the word "poly" is added in front. For example, polyacrylonitrile fiber is polymerized with acrylonitrile as raw material. The relative molecular mass of polymer compounds is very large, generally between 104 and 107. Since the basic composition of a polymer compound is the repetition of a certain unit of its macromolecules and is connected in the form of main valence bonds, the number of repetitions is called the degree of polymerization (expressed in surface), such as the fibers that make up cotton fibers. Macromolecules can be simply expressed as (C6H1005)n. n is the degree of polymerization. Different polymer compounds have different degrees of polymerization, and the degree of polymerization of various fabric fibers is also different. For example, the DP of cotton fiber is 2500～10000, and the DP of viscose fiber is 250～500. Regardless of the relative molecular mass or degree of polymerization, it can indicate the size of the molecular chain of a polymer compound, which is one of the important indicators for identifying the degree of fiber damage.

　　 The obvious difference between high molecular compound and low molecular compound is the relative molecular mass and the intermolecular force caused by large molecules. The intermolecular forces of polymer compounds include van der Waals forces, hydrogen bonds, etc. These forces have a great influence on the deformation or fracture of the molecules between fibers, the change of elasticity, and the coloring properties of various dyes. Due to the different structure of the main chain of macromolecules, the physical and chemical properties of polymer compounds are also different. They are manifested in different properties such as strength, elasticity, elongation, acid resistance, alkali resistance, oxidation resistance and reduction. These different characteristics are important for the formulation of dyeing and finishing. Craftsmanship is very important. The molecular chain of polymer compounds is very long, and the intermolecular binding force is very high, so there is only solid and liquid, not gas. The macromolecules in the solid polymer compound have a certain geometric arrangement, and the molecules are ordered and stacked regularly are called crystalline; those without a lattice structure are called amorphous, also called amorphous structure. When coloring, the dye generally can only enter the edge of the amorphous or crystalline area. Excessive external force and high temperature can damage the crystal structure of the fiber macromolecular chain or cause crystal melting. Amorphous linear polymer compounds exhibit three states with temperature change under the condition of the same external force, namely, glass state, high elastic state and viscous flow state. The determination of these three states and two transition temperatures (T9 is the glass state temperature and Tf is the viscous flow temperature) of the polymer compound is of useful significance for the finishing and application of polymers. For example, when the T of nylon is 50°C, the dye can only be dyed when the temperature exceeds Tg. For example, the Tf of polyester is about 240°C, so the setting temperature cannot exceed Tf. If it exceeds this temperature, the fiber will deform to the point that it cannot be dyed. Reply.

　　All kinds of fabric fibers have certain appearance and cross-sectional shapes. For example, the appearance of cotton fiber is naturally crimped, and the cross-section is waist-shaped; the main body of silk is silk, which is surrounded by sericin; wool has a scale layer and a cortex layer. Polyamide, polyester, polyacrylonitrile, and vinylon are commonly known as the four major fibers. Their cross-sections are similar. For example, the cross-sections of nylon and polyester are almost round; the cross-section of vinylon is waist-shaped with a clear skin-core structure. It is of great assistance to the identification of fabric fibers and the release of new materials. In addition, fiber modification technology is also changing day by day. Physical modification, such as making special-shaped fibers, elastic fibers, loose fibers, etc.; chemical modification, such as cationization of cotton fiber, acid modification of polyester, modification of polypropylene fiber with organometallic compounds, and plasma modification, etc., which greatly increase the number of new types The variety of fiber and the improved coloring performance of fiber make people's clothing and decoration more colorful.