Synthetic fibres. Types of synthetic fabrics, their characteristics Chemical properties of synthetic fibers

Modern technologies affected all spheres of human life. Perhaps the textile industry is the most striking example of science put at the service of everyday life. Thanks to chemical synthesis, a person has learned to obtain fibers with desired properties. Distinguish between artificial and synthetic fabrics.

Synthetics are made from polymers obtained by certain chemical reactions. The raw materials for it are oil products, natural gas or coal. Synthetic fabrics with special properties are used to make overalls, protective clothing for extreme conditions, and sports uniforms.

Artificial fibers are produced by physical processing of raw materials. The most famous example of such a fabric is viscose, obtained from cellulose (wood).

Fabrics made from synthetic fibers have a number of advantages and disadvantages compared to natural materials.

General properties of synthetic fibers

Despite all their diversity, most artificial materials have common features. The advantages of synthetic fabrics include the following qualities.

• Durability. Artificial fabrics have increased wear resistance, are not subject to decay, damage by pests and mold fungi. A special technology of bleaching and subsequent dyeing of the fiber ensures color fastness. Some groups of synthetic fabrics are unstable to sunlight.
• Ease. Synthetic clothing weighs much less than its natural counterparts.
• Dry quickly. Most synthetic fibers do not absorb moisture or have water-repellent properties, that is, they have low hygroscopicity.
• Due to large-scale industrial production and low cost of raw materials, most artificial fabrics have low cost. In production, high labor productivity and low cost are obtained, which stimulates the development of the industry. Many manufacturers adjust the technological characteristics of the material in accordance with the wishes of large customers.

The disadvantages are due to the fact that artificial material can have a bad effect on a living organism.

• Synthetics accumulate static electricity (electrify).
• Perhaps the occurrence of allergies, individual intolerance to chemical components.
• Most artificial fabrics do not absorb moisture well - accordingly, they do not absorb sweat and have low hygienic properties.
• They do not let air through - this is also important for the production of clothing and linen.

Some properties of synthetic fabrics can have both positive and negative meanings, depending on how the material is used. For example, if the fabric does not allow air to pass through, it is unhygienic for you. But outerwear made from such a material will be very appropriate for protection from adverse weather conditions.

Manufacture of synthetic fabrics

The first patents for the invention of synthetic fibers date back to the period of the 30s of the last century. In 1932, the production of polyvinyl chloride fiber was mastered in Germany. In 1935, polyamide was synthesized in the laboratory of the American company DuPont. The material is called nylon. Its industrial production began in 1938, and a year later it was widely used in the textile industry.

In the USSR, the course towards the widespread introduction of the achievements of chemical science was taken in the 1960s. Initially, synthetics were perceived as a cheap substitute for natural fabrics, then they began to use them for the manufacture of workwear and protective suits. As the scientific base developed, they began to create fabrics with various properties. The new polymers have undeniable advantages compared to natural fabrics: they are lighter, stronger and more resistant to aggressive environments.

Fabrics, artificial and synthetic, differ in the method of manufacture and indicators of the economics of production. Raw materials for the production of synthetics are much cheaper and more accessible, which is why this particular industry has received priority in development. Fiber macromolecules are synthesized from low molecular weight compounds. Modern technologies provide material with predetermined characteristics.

Threads are formed from melts or solutions. They can be single, complex or in the form of bundles to obtain fibers of a certain length (then yarn is produced from them). In addition to threads, film materials and stamped products (shoe and clothing parts) are formed from the initial synthetic mass.

Varieties of synthetics

Currently, several thousand chemical fibers have been invented, and new materials appear every year. According to the chemical structure, all types of synthetic fabrics are divided into two groups: carbochain and heterochain. Each group is subdivided into subgroups with similar physical and operational properties.

Carbon chain synthetics

The chemical chain of a macromolecule of carbon chain synthetic fabrics consists mainly of carbon atoms (hydrocarbons). The group is divided into the following subgroups:

• polyacrylonitrile;
• polyvinyl chloride;
• polyvinyl alcohol;
• polyethylene;
• polypropylene.

Heterochain synthetics

These are fabrics made of synthetic fibers, the molecular composition of which, in addition to carbon, includes atoms of other elements: oxygen, nitrogen, fluorine, chlorine, sulfur. Such inclusions give the original material additional properties.

Types of synthetic fabrics of the heterochain group:

• polyester;
• polyamide;
• polyurethane.

Lycra: polyurethane synthetic fabrics

Names used by trading corporations: elastane, lycra, spandex, neolan, dorlastan. Polyurethane threads are capable of reversible mechanical deformations (like rubber). Elastane is able to stretch 6-7 times, freely returning to its original state. It has low temperature stability: when the temperature rises to +120 °C, the fiber loses its elasticity.

Polyurethane threads are not used in their pure form - they are used as a frame, winding other fibers around. The material containing such synthetics has elasticity, stretches well, resilient, resistant to abrasion, perfectly breathable. Things made of fabrics with the addition of polyurethane threads do not wrinkle and retain their original shape, are resistant to light, and retain their original color for a long time. The fabric is not recommended to be strongly wrung out, twisted, dried in a stretched form.

Kapron: polyamide synthetics

The material got its name due to the amide group, which is part of the fabric. Kapron and nylon are the most famous representatives of this group. Main properties: increased strength, keeps its shape well, does not rot, light. At one time, kapron replaced the silk used to make parachutes.

Synthetic fibers of the polyamide group have low resistance to elevated temperatures (begins to melt at +215 ° C), they turn yellow in the light and under the influence of sweat. The material does not absorb moisture and dries quickly, accumulates and poorly retains heat. Women's tights and leggings are made from it. Capron and nylon are introduced into the composition of the fabric in an amount of 10-15%, which increases the strength of natural materials without compromising their hygienic properties. Socks are made from such materials and

Other trade names synthetic materials polyamide group: anid, perlon, meryl, taslan, jordan and helanca.

Velsoft - a thick fabric with pile, competes with terry. Children's clothes, bathrobes and pajamas, household items (towels and blankets) are sewn from it. The material is pleasant to the touch, breathable, does not wrinkle, does not shrink, does not shed. Washable, dries quickly. Printed pattern does not fade over time.

Lavsan: polyester fibers

Polyester synthetics have increased elasticity, wear resistance, fabrics from it do not shrink, do not wrinkle and keep their shape well. The main advantage in comparison with other groups of synthetic fabrics is increased heat resistance (withstands over +170 ° C). The material is hard, does not absorb moisture, does not collect dust, does not fade in the sun. In its pure form, it is used for the manufacture of curtains and curtains. In a mixture with used for the manufacture of dress and suit fabrics, as well as material for coats and Polyester fiber provides resistance to abrasion and creasing, and natural threads cause hygiene, which synthetic fabrics do not have. Names of fabrics made of polyester materials: lavsan, polyester, terylene, trevira, tergal, diolen, dacron.

Fleece is a synthetic soft fabric made of polyester, similar in appearance to sheep's wool. Fleece clothing is soft, light, warm, breathable, elastic. The material is easy to wash, dries quickly and does not need ironing. Fleece does not cause allergies, so it is widely used for the manufacture of children's clothing. Over time, the fabric stretches and loses its shape.

Polysatin is made from pure polyester or in combination with cotton. The material is dense, smooth and slightly shiny. Dries quickly, does not shrink, does not wear out, does not shed. It is used for the manufacture of bed linen, household products (curtains, tablecloths, upholstery for furniture), home clothes, ties and scarves. Very popular today bed sheets with a 3D pattern is made from polysatin.

Acrylic: polyacrylonitrile materials

In terms of mechanical properties, it is close to wool fibers, which is why acrylic is sometimes called "artificial wool". Synthetics are resistant to sunlight, it is heat-resistant, perfectly keeps its shape. Does not absorb moisture, hard, electrified, abraded.

It is used in combination with wool for the production of fabric for furniture, children's mattresses, tailoring of outerwear and the manufacture of artificial fur. Acrylic does not pill, making it an indispensable addition to wool knitting yarns. Things made of combined yarn stretch less, they are more durable and lighter.

Trade names of polyacrylonitrile materials: acrylan, nitron, kashmilon, dralon, dolan, orlon.

Spectra and dynema: polyolefin fibers

This group distinguishes between polyethylene and the lightest of all types of synthetics, polyolefin materials do not sink in water, are characterized by low hygroscopicity and good thermal insulation properties, the extensibility of the fiber is almost zero. They have low temperature stability - up to +115 °С. They are used when creating two-layer materials, for sewing sports and fishing clothes, filter and upholstery materials, tarpaulins, carpets. In combination with natural fibers - for the production of underwear and hosiery.

Trade names: spectrum, dynema, tekmilon, herculon, ulstrene, found, meraklon.

PVC synthetic fabrics

The material is characterized by high resistance to chemically aggressive substances, low electrical conductivity and instability to temperature effects (destroyed at 100°C). Shrinks after heat treatment.

In its pure form, protective clothing is made from it. With its help, a dense synthetic fabric is obtained - artificial leather, artificial fur and carpets are also made.

Trade names: teviron, chlorine, vignon.

Polyvinyl alcohol fibers

This group includes vinol, mtilan, vinylon, curalon, vinalon. They have all the advantages of synthetics: durable, wear-resistant, resistant to light and temperature effects. In terms of extensibility and elasticity, they have average indicators. Distinctive feature- they absorb moisture well, products made from synthetic fabrics of this group have a high hygroscopicity, comparable to the properties of cotton products. Under the influence of water, vinol lengthens and shrinks a little, its strength decreases. Compared to other chemical fibers, it is less resistant to chemical attack.

Vinol is used for the manufacture of clothing, underwear, in combination with cotton and viscose - for the production of hosiery. The material does not roll, does not wipe, has a pleasant sheen. The disadvantage of wine products is that they quickly become dirty.

Mtilan is used for the production of surgical sutures.

The combination of different fibers gives interesting technological characteristics. A striking example is microfiber, which is widely known today. It is made from a combination of nylon and polyester fibers. Microfiber does not roll, does not shed, has a high hygroscopicity, and dries quickly. It is used for the production of knitted and non-woven fabrics. Depending on the thickness of the fiber and its modification, the softness and wear resistance of the final product vary. Microfiber is not mixed with other fibers, the care of products is extremely simple - they are not afraid of washing, dry cleaning and temperature effects. Thanks to the many air pores, the fabric helps to maintain optimal body temperature, but at the same time perfectly protects from the wind. Microfiber is used to make sports and outerwear, home textiles, napkins and sponges for cleaning.

As you can see, chemically synthesized fibers are widely used in the production of light industry goods. They are used to make sportswear and overalls, fabrics for furniture and interior decoration, the whole range of everyday clothes: from underwear to materials for coats and faux fur. Modern fabrics have a number of advantages inaccessible to their predecessors: they can be hygroscopic, "breathable" and retain heat well. The combination of different fibers in one thread, as well as the creation of multilayer fabrics, allow manufacturers to fully meet the demands of the modern world.

Synthetic fibers are called fibers, upon receipt of which the synthesis of simple molecules occurs. Synthetic fibers include: lavsan, nitron, capron, chlorin, vinol, polyethylene, polypropylene and other fibers. Depending on the raw materials, the following polymers are obtained: polyamide, polyester, polyacrylonitrile, polyvinyl chloride, polyvinyl alcohol, polyurethane. A feature of the creation of a chemical fiber is that the formation process is at the same time its spinning.

Polyamide fibers. The most widely used polyamide kapron fibers. The initial raw material for the production of kapron fiber is benzene and phenol(products of coal processing). Processed in chemical plants caprolactan. Capron resin is processed from capronolactan. This is a melt that is pressed through the slot from the die and exits in the form of thin streams that solidify when blown with air. One machine can have 60 - 100 dies. Depending on the type of chemical fiber, the spinneret has a different number of holes of various sizes. The fibers are stretched, twisted, processed hot water to fix the structure. Methods have also been developed for producing hollow nylon fiber, which is shaped and highly shrinkable. It is used for the manufacture of fabrics for hosiery, knitwear, sewing threads and technical purposes. Manufacturing processes anida and enanthe similar to the manufacture of kapron fiber.

Properties polyamide fibers: lightness, elasticity, high tensile strength, high chemical resistance, frost resistance, resistance to microorganisms and mold. The fibers dissolve in concentrated acids and phenol.

Are burning fibers with a bluish flame, forming a melted brown ball at the end.

belongs to polyamide silk- which is used for the manufacture of light dress and blouse fabrics and megalope- chemically modified fiber, hygroscopic, durable, resistant to abrasion, gives the fabric an increased shimmering sheen. Polyamide profiled thread - trilobal used for silk-type fabrics similar in appearance to natural silk.

polyester fibers. Lavsan produced from oil refinery products. Does not change its properties when wet.

Properties lavsan fibers: they are light, elastic, moth-resistant, resistant to decay, destroyed by acids and alkalis, hygroscopicity is very low 0.4%. During wet heat treatment, a temperature of 140ºС is maintained. When brought into the flame, lavsan melts, then slowly burns with a yellow smoky flame.

Polyurethane fibers. By their own physical and mechanical properties refers to elanomers, i.e. has a high rate of elastic recovery. Breaking elongation 600% - 800%. When the load is removed, the elasticity is immediately restored by 90%, and after a minute - 95%. These fibers are low hygroscopic - 1 - 1.5%, heat-resistant, abrasion-resistant, well-dyed. They are used for the manufacture of knitwear, tapes in sports corsetry, and medical elastic products.

Polyacrylonitrine fibers(PAN). Nitron It is produced from the products of coal, oil and gas processing. Softer and silkier to the touch than lavsan and kapron. The strength is more than two times less than the strength of nylon and lavsan fiber. Elongation at break 16 - 22%, hygroscopicity 1.5%.

Nitron has a number of valuable properties: resistant to mineral acids, alkalis, organic solvents for dry cleaning, resistant to bacteria, mold, moths. In terms of heat-shielding properties, nitron is superior to wool. At a temperature of 200 - 250 ° C, nitron softens. It burns with a bright, smoky flame with flashes.

Polyvinyl chloride fibers (PVC). Chlorine made from ethylene or acetylene. Possesses resistance to action of water, acids, alkalis, oxidizing agents, does not decay, has no gloss.

According to heat protection properties not inferior to wool. The strength in the wet state does not change, it has a low resistance to light weather. Wet heat treatment - at 70%. The disadvantage is low heat resistance. Chlorine does not burn, does not support combustion; Chlorine is electrified, therefore it is used for medical underwear, as well as for obtaining embossed silk fabrics, faux fur and workwear fabrics (fishermen, foresters, firefighters, etc.).

Resistance to aggressive environments, high mechanical strength, elasticity and other valuable qualities have made synthetic fibers indispensable for modern textile production.

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Some natural cellulose fibers are processed and processed for specific uses. Well-known fibers such as viscose, acetate, etc. are obtained by processing various natural polymers.

The first artificial fibers to be developed and manufactured used polymers of natural origin, more precisely cellulose, which is a raw material available in large quantities in flora.

Cellulose is a natural polymer that makes up the living cells of all vegetation. It is the material at the center of the carbon cycle and the most abundant and renewable biopolymer on the planet.

Cotton sheets and wood pulp, viscose, copper ammonium silk, cellulose acetate (secondary and triacetate), polynose, high wet modulus (HMW) fibre.

• Cellulose is one of the many polymers found in nature.
• Wood, paper and cotton contain cellulose. Cellulose is an excellent fiber.
• Cellulose is made up of repeating units of monomeric glucose.
• The three types of regenerated cellulose fibers are viscose, acetate and triacetate, which are derived from the cell walls of short cotton fibers called linters.
• Paper, for example, is almost pure cellulose.

Viscose

The word "viscose" was originally applied to any fiber made from cellulose and therefore contained cellulose acetate fibers. However, the definition of viscose was described in 1951 and now includes textile fibers and fibers composed of regenerated cellulose, excluding acetate.

• Viscose is a regenerated cellulose fibre.
• It is the first man-made fiber.
• It has a jagged round shape with a smooth surface.
• When wet, viscose loses 30-50% of its strength.
• Viscose is formed from natural polymers and therefore is not a synthetic fiber, but an artificial regenerated cellulose fiber.
• The fiber is sold as rayon.
• There are two main varieties of viscose fiber, namely viscose and copper ammonium.

Acetate

Derivative fiber in which the fiber-forming substance is cellulose acetate. Acetate is obtained from cellulose by refining cellulose from wood pulp with acetic acid and acetic anhydride in the presence of sulfuric acid.

Characteristics of acetate fiber:

• Luxurious to the touch and look
• Wide range of colors and glosses
• Excellent drape and softness
• Relatively fast drying
• Resistant to shrinkage, moths and powdery mildew

Special dyes have been developed for acetate because it does not accept dyes commonly used for cotton and viscose.

Acetate fibers are manufactured fibers in which the fiber-forming substance is cellulose acetate. Cellulose ethers triacetate and acetate are formed by acetylation of cotton linters or wood pulp using acetic anhydride and an acid catalyst in acetic acid.

Acetate and triacetate fibers are very similar in appearance to viscose with consistent strength. Elements and triacetates are moderately stiff fibers and have good flexural and deformation resilience, especially after heat treatment.

The abrasion resistance of acetate and triacetate is poor and these fibers cannot be used in applications requiring high abrasion and wear resistance; however, the abrasion resistance of these fibers is excellent. Although acetate and triacetate are moderately absorbent, their absorption cannot be compared to pure cellulose fibers. To the touch, acetate fabrics are somewhat softer and more flexible than triacetate. The fabrics of both fibers have excellent drape characteristics. Acetate and triacetate fabrics have a pleasant appearance and a high degree of sheen, but the sheen of these fabrics can be modified by adding a matting agent.

Both acetate and triacetate are susceptible to attack by a number of household chemicals. Acetate and triacetate are attacked by strong acids and bases and oxidizing bleaches. Acetate has only a slight resistance to sunlight, while the solar resistance of triacetate is higher. Both fibers have good heat resistance below their melting points.

Acetate and triacetate cannot be dyed with dyes used for cellulose fibers. These fibers can be satisfactorily dyed with disperse dyes at moderate to high temperatures, producing crisp, vibrant hues. Acetate and triacetate dry quickly and can be dry cleaned.

artificial fibres. Among the chemical fibers in terms of output, the first place is occupied by artificial viscose fiber. The main substance for the production of viscose fiber is wood pulp and cheap chemicals available. The advantage of viscose fiber is the high economic efficiency of its production and processing. So, in the production of 1 kg of viscose yarn, labor costs are 2-3 times lower than the costs for the production of the same yarn from cotton and 4.5-5 times lower than the production of 1 kg of wool yarn.

Viscose fiber is produced in various lengths and thicknesses. The thickness of the elementary fiber of viscose silk is from 0.5 to 0.2 tex.

Viscose fibers have sufficient strength, but when wet, their strength drops to 50-60%. Their disadvantage is the ability to shrink, i.e., shrink in length, especially after washing the products.

These fibers have high hygienic properties, as they are characterized by the ability to absorb moisture well. Viscose fibers are heat resistant.

When heated, they do not soften and withstand heating without destruction up to 150 °. At higher temperatures (175-200°) the process of fiber decomposition begins.

Viscose fibers with enhanced properties are called polynose. By their properties, they are close to cotton fiber.

Based on cotton or wood pulp, other artificial fibers are obtained - copper ammonia and acetate.

Copper-ammonia fiber in its properties resembles viscose fiber. It is produced in small quantities, since its production is much more expensive than the production of other man-made fibers. It is mainly used in mixtures with wool.

There are two types of acetate fibers: diacetate and triacetate. Diacetate fibers are commonly referred to as acetate fibers. Acetate fibers have sufficient strength. Their breaking elongation is 18-25%. The tensile strength of acetate fiber in the wet state is reduced by 40-50%, and triacetate - by 10-15%. Acetate fiber absorbs about 6.5% of moisture, and triacetate - no more than 1-1.5%.

Acetate fibers in their properties occupy an intermediate position between artificial and synthetic fibers.

Unlike viscose, acetate fibers are thermoplastic and begin to deform at a temperature of 140-150 °.

The use of acetate fibers mixed with viscose can significantly reduce the wrinkling of products. Acetate fibers are not dyed with dyes used for dyeing viscose fibers, so the use of acetate fibers mixed with viscose fibers allows you to create various color effects, ennoble the front surface of the fabric.

Of other artificial fibers, glass and metal are used in the production of fabrics; metal threads are used to give fabrics various decorative effects; they are called alunit, lurex, metlon, etc.

Synthetic fibres. Of the synthetic fibers, polyamide fibers are most widely used, which include nylon, anide, enanth and other fibers. In our country, among polyamide fibers, nylon fiber occupies the first place. To obtain it, caprolactam resin is used, which is obtained by chemical synthesis from relatively simple organic substances.

Polyamide fibers have a number of valuable properties: high tensile strength, resilience and exceptional abrasion resistance.

The advantage of polyamide fibers is their high resistance to abrasion and repeated deformations.

Synthetic fibers

For thousands of years, mankind has used for its needs natural fibers of plant (linen, cotton, hemp) and animal (wool, silk) origin. In addition, mineral materials, such as asbestos, were also used.

Fabrics made from these fibers were used to make clothes, technical needs, etc.

Due to the growth of the world's population, natural fibers have become scarce. That is why there was a need for their substitutes.

The first attempt to obtain artificial silk was made in 1855 by the Frenchman Audemars on the basis of nitrocellulose. In 1884, the French engineer G. Chardonnay developed a method for obtaining artificial fiber - nitro silk, and since 1890 a wide production of artificial silk was organized using the nitrate method with the formation of threads using spinnerets. Especially effective was the work that began in the 90s of the XIX century. production of silk from viscose. Subsequently, this method was most widely used, and now viscose silk accounts for approximately 85% of the world's production of man-made fibers. In 1900, the world production of viscose silk amounted to 985 tons, in 1930 - about 200 thousand tons, and in 1950 the production of viscose silk reached almost 1600 thousand tons.

In the 1920s, the production of acetate silk (from cellulose acetate) was mastered. In appearance, acetate silk is almost indistinguishable from natural silk. It is slightly hygroscopic and, unlike viscose silk, does not wrinkle. Acetate silk is widely used in electrical engineering as an insulating material. Later, a method was discovered for obtaining acetate fibers of extremely high strength (a cord with a cross section of 1 cm 2 can withstand a load of 10 tons).

Based on the progress of chemistry throughout the 20th century. in the USSR, England, France, Italy, the USA, Japan and other countries, a powerful industry of artificial fiber was created.

On the eve of World War I, only 11 thousand tons of artificial fiber were produced worldwide, and 25 years later, the production of artificial fiber pushed back the production of natural silk. If in 1927 the production of viscose and acetate silk was about 60 thousand tons, then in 1956 the world production of artificial - viscose and acetate - fibers exceeded 2 million tons.

The difference between natural, artificial and synthetic fibers is as follows. Natural (natural) fiber is completely created by nature itself, artificial fiber is made by human hands, and synthetic fiber is created by man in chemical plants. In the synthesis of synthetic fibers from simpler substances, more complex macromolecular compounds are obtained, while artificial materials are formed due to the destruction of much more complex molecules (for example, cellulose molecules in the production of methyl alcohol by dry distillation of wood).

Nylon, the first synthetic fiber, was discovered in 1935 by the American chemist W. Carothers. Carothers first worked as an accountant, but later became interested in chemistry and enrolled at the University of Illinois. Already in the third year he was assigned to lecture on chemistry. In 1926, Harvard University elected him professor of organic chemistry.

In 1928, a sharp turn took place in the fate of Carothers. The largest chemical concern "Dupont de Nemours" invited him to head the laboratory of organic chemistry. Ideal conditions were created for him: a large staff, the most modern equipment, freedom in choosing research topics.

This was due to the fact that a year earlier the concern had adopted a strategy for theoretical research, believing that in the end they would bring significant practical benefits, and therefore profit.

And so it happened. Carothers' laboratory, investigating the polymerization of monomers, after three years of hard work achieves an outstanding success - a polymer of chloroprene is obtained. Based on it, in 1934, the DuPont concern began the industrial production of one of the first types of synthetic rubber - polychloroprene (neoprene), which, in its qualities, can successfully replace the scarce natural rubber.

However, Carothers considered the main goal of his research to be a synthetic substance that could be turned into fiber. Using the method of polycompensation, which he studied at Harvard University, in 1930 Carothers obtained a polyester as a result of the interaction of ethylene glycol and sebacic acid, which, as it turned out later, was easily drawn into fiber. This was already a great achievement. However practical application this substance could not have, as it was easily softened by hot water.

Further numerous attempts to obtain a commercial synthetic fiber were unsuccessful, and Carothers decided to stop working in this direction. The management of the concern agreed to close the program. However, the head of the chemical department opposed this outcome. With great difficulty, he persuaded Carothers to continue his research.

Rethinking the results of his work in search of new ways to continue it, Carothers drew attention to the recently synthesized polymers containing amide groups in the molecule - polyamides. This choice proved to be extremely fruitful. Experiments have shown that certain polyamide resins, squeezed through a spinneret made from a thin medical syringe, form filaments from which fiber can be made. The use of new resins seemed very promising.

After new experiments, Carothers and his assistants on February 28, 1935 received polyamide, from which it was possible to produce a strong, elastic, elastic, waterproof fiber. This resin, isolated as a result of the reaction of hexamethylenediamine with adipic acid, followed by heating the resulting salt (AG) in vacuum, was called "polymer 66", since the initial products contained 6 carbon atoms. Since they worked on the creation of this polymer simultaneously in New York and London, the fiber from it was called "nylon" - after the initial letters of these cities. Textile experts recognized it as suitable for the commercial production of yarn.

Over the next two years, DuPont scientists and engineers developed in the laboratory technological processes production of polymer intermediates and nylon yarn and designed a chemical pilot plant.

On February 16, 1937, nylon was patented. After many experimental cycles, in April 1937 fiber was obtained for an experimental batch of stockings. In July 1938, the construction of an experimental enterprise was completed.

On April 29, 1937, three days after Carothers turned 41, he passed away by taking potassium cyanide. An outstanding researcher was haunted by the obsession that he did not succeed as a scientist.

Nylon cost $6 million to develop, more than any other public use product. (For comparison, the United States spent $2.5 million to develop television.)

Outwardly, nylon resembles natural silk and approaches it in chemical structure. However, in terms of its mechanical strength, nylon fiber is approximately three times superior to viscose silk, and natural - almost two times.

DuPont has long guarded the secret of the nylon manufacturing process. And even she made the necessary equipment for this. Both employees and wholesalers of the goods necessarily signed a non-disclosure agreement regarding "nylon secrets".

The first commercial product to hit the market was nylon bristle toothbrushes. Their release began in 1938. Nylon stockings were demonstrated in October 1939, and from the beginning of 1940, nylon fiber began to be produced in Wilmington, which knitting factories bought for the manufacture of stockings. Thanks to the mutual agreement of trading companies, stockings from competing manufacturers appeared on the market on the same day: May 15, 1940.

Mass production of nylon products began only after World War II, in 1946. And although many other polyamides (kapron, perlon, etc.) have appeared since then, nylon is still widely used in the textile industry.

If in 1939 the world production of nylon was only 180 tons, then in 1953 it reached 110 thousand tons.

Nylon plastic was used in the 1950s to manufacture ship propellers for small and medium-sized ships.

In the 40-50s of the XX century. other synthetic polyamide fibers also appeared. So, in the USSR, capron was the most common. The raw material for its production is cheap phenol, produced from coal tar. About 0.5 tons of resin can be obtained from 1 ton of phenol, and nylon can be made from it in an amount sufficient to make 20–25 thousand pairs of stockings. Kapron is also obtained from oil refining products.

In 1953, for the first time in the world in the USSR, a polymerization reaction between ethylene and carbon tetrachloride was carried out on a pilot scale, and the initial product for the industrial production of enanth fiber was obtained. The scheme of its production was developed by a team of scientists led by A. N. Nesmeyanov.

In terms of basic physical and mechanical properties, enanth not only was not inferior to other known polyamide fibers, but also surpassed nylon and nylon in many respects.

In the 50s and 60s. of the last century, the production of polyester, polyacrylonitrile synthetic fibers began.

Polyester fibers are formed from a polyethylene terephthalate melt. They have excellent heat resistance, retaining 50% strength at 180°C, are flame retardant and weather resistant. Resistant to solvents and pests: moths, molds, etc. Polyester thread is used for the manufacture of conveyor belts, drive belts, ropes, sails, fishing nets, hoses, as the basis for tires. Monofilament is used for the production of mesh for paper machines, racket strings. In the textile industry, a thread made of polyester fibers is used to make knitwear, fabrics, etc. Lavsan belongs to polyester fibers.

Polyacrylonitrile fibers are similar in properties to wool. They are resistant to acids, alkalis, solvents. They are used for the manufacture of outerwear, carpets, fabrics for suits. In a mixture with cotton and viscose fiber, polyacrylonitrile fibers are used to make linen, curtains, and tarpaulins. In the USSR, these fibers were produced under the trade name Nitron.

Many synthetic fibers are made by forcing a polymer melt or solution through spinnerets 50 to 500 micrometers in diameter into a cold air chamber where the filaments solidify and become fibers. A continuously formed thread is wound on a bobbin.

The acetate fibers are cured in hot air to evaporate the solvent, while the viscose fibers are cured in precipitation baths with special liquid reagents. The stretching of the fibers on the reels during formation is used in order for the chain polymer molecules to take on a clearer order.

The properties of the fibers are influenced by various methods: by changing the extrusion speed, the composition and concentration of substances in the bath, by changing the temperature of the spinning solution, bath or air chamber, by varying the size of the die opening.

An important characteristic of the strength properties of the fiber is the breaking length, at which the fiber breaks under its own gravity.

For natural cotton fiber, it varies from 5 to 10 km, for acetate silk - from 12 to 14, for natural - from 30 to 35, for viscose fiber - up to 50 km. Fibers made of polyesters and polyamides have greater strength. So in nylon, the breaking length reaches 80 km.

Synthetic fibers have replaced natural fibers in many areas. The total volume of their production is almost equal.