Basic textile knowledge

1. Fiber: natural or synthetic elongated material with a length much larger than its diameter and a certain degree of flexibility.

(2) textile fiber (textile+fibre) : with a certain length, densification and toughness fineness is very fine (diameter is generally a few microns to tens of microns), the length is one hundred times larger than the diameter, or even more than a thousand times and has a certain processing performance and use performance of slender substances called textile fibers.

1) Linear density and length of fibers

The linear density of the fiber refers to the thickness of the fiber, and the length of the fiber refers to the length of the fiber. Textile fibers have a certain linear density and length, in order to make the fibers embrace each other, which is one of the necessary conditions for textile processing and make the product have use value. The fabric made of finer fibers is softer, the luster is softer, and can be made into a relatively thin fabric, and can also be made of clothing fabrics with good air permeability and good imitation silk effect. But the fabric made of fine fiber is easy to fuzz and pilling. Coarse fiber fabrics can be manufactured as stiff, rugged and thick fabrics.

Similarly, the length of textile fibers is also closely related to textile and product quality. Long fiber length, good length uniformity and less short fiber content are beneficial to textile processing and product quality. Under the same conditions, if the fiber is longer, the yarn strength is high, the dry strip is uniform, the yarn surface is smooth, the fabric made is good fastness, the appearance is smooth, and it is not easy to fuzz and pilling. In addition, under the premise of ensuring a certain quality of yarn, the longer the fiber, the finer the yarn can be spun, which can be used to make a lighter fabric.

In textile fibers, the linear density and length of natural fibers are uneven, and sometimes the difference is larger, which varies with the fiber varieties, growth conditions and so on. The chemical fiber is artificially manufactured, and the linear density and length of the fiber can be controlled and determined within a certain range according to the requirements of fiber processing and use.

2) Chemical resistance of fiber

It refers to the resistance of fibers to the destruction of various chemical substances. Fiber in textile dyeing and finishing processing, will be different degrees of contact with water, acid, alkali, salt and other chemical substances, so as a textile fiber must have a certain chemical resistance. Correct understanding of the chemical resistance of various textile fibers, reasonable selection of appropriate processing conditions, in order to correctly use a variety of fiber products.

Among all kinds of textile fibers, cellulose fibers have strong resistance to alkali and weak resistance to acid. The chemical resistance of protein fiber is different from that of cellulose fiber, and its resistance to acid is stronger than that of alkali, and protein fiber will be damaged to varying degrees in strong alkali or weak alkali, and even lead to decomposition. The chemical resistance of synthetic fibers is stronger than that of natural fibers, such as the acid and alkali resistance of polypropylene and chlorinated fiber.

3) Mechanical properties of textile fibers

It refers to the performance of textile fiber deformation under the action of various external forces. External forces include stretching, compression, bending, torsion, friction and other forms. The mechanical properties of textile fibers should include fiber strength, elongation, elasticity, wear resistance, elastic modulus, etc.

A fiber strength: The strength of the fiber refers to the ability of the fiber to resist external damage, which largely determines the durability of textile goods. The strength of the fiber can be expressed by the absolute strength of the fiber, which refers to the maximum load that the fiber can withstand under the action of continuous increasing load until it breaks. Its legal unit is Newton (N) or centinewton (cN). It used to be expressed in grams or kilograms. Since the strength of the fiber is related to the thickness of the fiber, the absolute strength is not comparable for fibers of different thickness, so the relative strength is commonly used to represent the strength of the fiber. Relative strength refers to the maximum tensile force that the fiber can withstand per unit linear density (per tert or per denier). The legal unit of measurement is Niu/T (N/tex) or Li Niu /t (cN/tex). It used to be expressed in gram/denier.

B fiber elasticity: fiber and its products in processing and use, are subject to external force, and produce the corresponding deformation. When the action of external force is removed, part of the deformation of the fiber can be restored, while the other part of the deformation will not be restored. According to this characteristic of the fiber, the deformation of the fiber can be divided into three parts, that is, when the external force can be immediately restored after the deformation of this part is called rapid elastic deformation; When the external force is removed, this part of the deformation that can slowly recover is called slow elastic deformation; When the external force is removed, this part of the deformation that cannot be restored is called plastic deformation. The elasticity of fiber refers to the resilience of fiber deformation. The commonly used index to indicate the elastic size of the fiber is the elastic recovery rate or resilience rate of the fiber. It refers to the percentage of rapid elastic deformation and slow elastic deformation of a certain time in the total deformation. If the elastic recovery rate of fiber is high, the elasticity of fiber is good and the ability of deformation recovery is strong. Textiles made of elastic fibers have good dimensional stability, are not easy to wrinkle during use, and are more wear-resistant. For example, polyester has excellent elasticity, and the clothing made of it has the characteristics of crisp and wear-resistant.