Synthetic fibers are chemical fibers produced by spinning and post-processing artificially synthesized linear polymers with suitable molecular weight and soluble (or fusible) properties. Compared with natural fibers and man-made fibers, synthetic fiber production is not limited by natural conditions. In addition to the general superior properties of chemical fibers, such as high strength, light weight, easy washing and quick drying, good elasticity, and resistance to mildew, synthetic fibers have certain unique properties.
Filament yarn
In the manufacturing process of synthetic fibers, spinning After the silk fluid (melt or solution) is spun into shape and post-processing, the fiber with a length of kilometers is called filament. Filament includes monofilament, multifilament and cord yarn.
01 Monofilament
Originally refers to a monofilament spun with a single-hole spinneret. A continuous single fiber, but in practical applications it often also includes small-hole filaments composed of 3 to 6 single fibers spun from 3 to 6 hole spinnerets. Thick synthetic fiber monofilaments (0.08-2mm in diameter) are called bristle filaments and are used to make ropes, brushes, daily net bags, fishing nets or industrial filter cloths; thinner polyamide monofilaments are used to make Transparent women’s socks or other high-end knitwear.
02 Multifilament
A thread composed of dozens of single fibers. The multifilament of chemical fiber is generally composed of 8 to 100 single fibers. The vast majority of clothing fabrics are woven with multifilament yarns, because multifilament yarns composed of multiple single fibers are more flexible than single yarns of the same diameter.
03 cord yarn
From more than a hundred to several A thread composed of hundreds of single fibers used to make tire cord fabric, commonly known as cord yarn.
Short fibers
Chemical fiber products are cut into several centimeters To a length of more than ten centimeters, fibers of this length are called short fibers. According to different cutting lengths, short fibers can be divided into cotton short fibers, wool short fibers, and medium-long short fibers.
01 Cotton type short fiber
The length is 25~38mm, the fiber is thin (linear density (1.3~1.7dtex), similar to cotton fiber, mainly used for blending with cotton fiber, such as blending cotton-type polyester short fiber with cotton fiber, and the resulting fabric is called “polyester-cotton” fabric.
02 Wool type short fiber
The length is 70~150mm, The fiber is thicker (linear density 3.3~7.7dtex), similar to wool, and is mainly used for blending with wool. For example, wool-type polyester short fiber is blended with wool, and the resulting fabric is called “wool-polyester” fabric.
03 Medium-long fiber
The length is 51~76mm, and the thickness of the fiber is between cotton type and wool type (linear density is 2.2~3.3dtex), mainly used for weaving medium and long fiber fabrics. In addition to being blended with natural fibers, short fibers can also be blended with short fibers of other chemical fibers. The resulting blended fabric has good overall properties.
In addition, short fibers can also be spun pure. In the current production of chemical fibers around the world, the output of short fibers is higher than that of filaments. According to fiber characteristics, some varieties (such as nylon) mainly produce filaments; some varieties (such as acrylic) mainly produce short fibers; and some varieties (such as polyester) have a relatively close ratio of the two.
Thick and detailed wire
Thick and detailed wire is referred to as T&T wire, from The alternating thick and detailed parts can be seen in its appearance, and the alternating dark and light color changes can be seen after the silk strips are dyed. Thick and thin filaments are manufactured using uneven drafting technology after spinning. The difference in properties between the two resulting filaments can be controlled during production. Their distribution is irregular and in a natural state.
The thick part of the thick and thin filaments has low strength, long elongation at break, strong heat shrinkage, good dyeability, and is easy to be processed by alkali reduction. It can be developed by taking full advantage of these characteristics. Textiles with unique properties. The physical properties of thick and fine filaments are related to factors such as the diameter ratio of thick and fine filaments.
Generally thick and thin filaments have high breaking elongation and boiling water shrinkage and low breaking strength and yield. Its strong shrinkage property can mix thick and fine filaments with other filaments to form different shrinkage mixed filaments. In addition, problems such as the easy deformation and low strength of thick sections of thick filaments should be paid attention to during the weaving, dyeing and finishing processes.
The initial thick and thin wires were round wires. With the development of thick and thin wire production technology, some special thick and thin wires have appeared one after another, such as special-shaped wires. Thick and thin yarns, mixed fiber thick and thin yarns, micro-porous thick and thin yarns, and fine-denier thick and thin yarns, etc., may have special feel and style, or special absorbency, and are mostly used to develop high-end fabrics.
Textured yarn
Textured yarn includes all yarns that have been textured Textured yarns, such as elastic yarn and bulked yarn, are all deformed yarns.
01 Elastic yarn
That is, deformed filament, which can be divided into high elastic yarn and low elastic yarn Two kinds of silk. Elastic yarn has good stretchability and fluffiness, and its fabric has good elasticity and fluffiness.Inorganic microparticles are added to the fiber, and after spinning and forming, reduction processing is performed to eliminate the inorganic microparticles and form numerous microscopic pits on the fiber surface. Due to the reduced friction between monofilaments, super-draping fiber products have super-draping properties and a unique feel that is unmatched by natural fibers.
Easily dyeable synthetic fibers
Synthetic fibers, especially polyester Ester fiber has poor dyeability and is difficult to dye into dark colors. Chemical modification can improve its dyeability and dyeing depth. This modified synthetic fiber is called easily dyeable synthetic fiber and mainly includes cationic fibers. Dyeable polyester fiber, cationic deep-dyed polyamide fiber, acid-dyeable polyacrylonitrile fiber and polypropylene fiber, etc. Easily dyeable synthetic fibers not only expand the dyeable range of fibers and reduce the difficulty of dyeing, but also increase the variety of textile designs and colors.
High-performance fiber
High-performance fiber has special physical and chemical properties structure, one or more performance indicators are significantly higher than ordinary fibers, and the acquisition and application of these properties are often related to high and new technologies such as aerospace, aircraft, oceans, medicine, military, optical fiber communications, bioengineering, robots, and large-scale integrated circuits. Field-related, so high-performance fiber is also called high-tech fiber.
High-performance fibers are usually distinguished according to their special properties, such as high strength and high modulus, high adsorption, high elasticity, high temperature resistance and flame retardant, Various fiber materials such as light conduction, electrical conduction, efficient separation, radiation protection, reverse osmosis, corrosion resistance, medical and pharmaceutical fibers. High-performance fibers are mainly used in the manufacture of industrial textiles, but some of them can also be used to develop decorative textiles and clothing textiles, and the performance of these two types of textiles can be significantly improved.
Nanofibers
Fibers with a diameter less than 100nm are usually called nanofibers (1nm equals 10m , that is, 10 μm, which is only the length of 10 hydrogen atoms lined up). Currently, some people also call fibers with nanoscale (i.e. particle size less than 100nm) powder fillers added as nanofibers.
At present, the thinnest nanofiber is a chain of single carbon atoms. This kind of carbon nanotube is known as the king of nanomaterials. The reason is that it is so thin that it is difficult for ordinary instruments to detect it. The observed materials have magical abilities: ultra-strong, ultra-flexible, and strangely magnetic. Because the distance between carbon atoms in carbon nanotubes is short and the diameter of the tube is small, the fiber structure is less likely to have defects. Its strength is 100 times that of steel and 200 times that of ordinary fibers, while its density is only 1/6 of steel. A rope made of it can be pulled from the earth to the moon without being broken by its own weight.
It has strange electrical conductivity, with both metal conductivity and semiconductor properties. Even different parts of a carbon nanotube can show different conductivities due to structural changes. Using it to make rectifiers can replace silicon chips, which will cause major changes in electronics and make computers extremely small.
Nano devices made of carbon nanotubes can be used to assemble nanorobots, such as mosquito planes, ant tanks, etc., which can be used in military and medical applications. Carbon nanotubes can be used to make hydrogen storage materials and develop hydrogen into a clean energy source for human services. In addition, carbon nanotubes can also be used as stealth materials, catalyst carriers and electrode materials. Nanofibers can support the arrangement of “nano machines” and connect the integrated array of “nano machines” into large-scale systems.
When the fineness of most materials reaches the nanometer level, their physical and chemical properties show unconventional properties, such as:
01 Surface effect
The smaller the particle size, the larger the surface area, because the surface particles lack the connection between adjacent atoms. Coordination, so the surface energy increases and is extremely unstable. It easily combines with other atoms and shows strong activity. After the fineness of the fiber reaches the nanometer level, the relationship between its diameter, specific length and specific surface area is shown in the table below.
02 Small size effect
When the size of the particles is small enough to match the wavelength of the light wave, the conduction electrons When the de Broglie wavelength is similar to or smaller than the coherence length or transmission depth of the superconducting state, its periodic boundary conditions will be destroyed, and the acoustic, optical, electromagnetic, thermodynamic and other properties of the particles will change, such as the melting point Reduce, color separation and discoloration, absorb ultraviolet rays, shield electromagnetic waves, etc.
03 Quantum size effect
When the size of the particle is small to a certain value, the Fermi energy The electron energy level near the energy level changes from quasi-continuous to discrete energy level. At this time, the material that was originally a conductor may become an insulator, and the material that was originally an insulator may become a superconductor.
04 Macroscopic quantum tunneling effect
The tunneling effect means that tiny particles can Passing through an object is like having a tunnel inside. The manufacturing of nanofibers can be roughly divided into three categories: molecular technology preparation methods, spinning preparation methods, and biological preparation methods. </p
