Post synthetic fibers. Synthetic fibres. History of invention and production. See what "synthetic fiber" is in other dictionaries

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Recent developments in the field of synthetic fiber chemistry.

Recent advances in chemical technology give hope for the production of hollow chemical fibers in the very near future. This technology is already being mastered for the use of new materials in membrane technologies.

The Dutch chemical company "DCM" in the early 80s launched the production of a new polymeric heavy-duty material - polyethylene fiber. When tested, its tensile strength was 10 times higher than that of steel wire of the same thickness.

In 1985, according to the authoritative magazine "Design News", a technology was developed for the production of heavy-duty fiber, called "Spectrum - 900". It is formed from a jelly-like high molecular weight polyethylene using centrifuges. In addition to a high degree of strength, this fiber has a high abrasive resistance, moisture resistance, and lightness. Therefore, rocket hulls, high-pressure vessels, artificial joints, and sails can be made from it ...

A method for producing heavy-duty synthetic fibers of considerable length from silicon carbide was developed by the Japanese chemist Seishi Yajima. These fibers are 1.5 times stronger than the best grades of steel. Moreover, the strength of the material is not lost even with prolonged heating up to +1200˚С.

In 1983, reports appeared in the world press about the creation of a synthetic fabric that remained heat-resistant when heated to + 1400 ° C.

Previously, a synthetic organic material was known that can withstand temperatures up to 10 thousand degrees. It was obtained back in the early 60s and went down in history under the name pluto. Its molecule consisted of carbon, hydrogen, oxygen and nitrogen atoms. At the same time, pluton had low strength, inferior to capron by 9-10 times. The most heat-resistant fiber is produced today in the industry under the trade name Kevlar.

polyester fibers type lavsan have high rates of light, mold and weather resistance. In addition, this synthetic material has an excellent resistance indicator and does not react to organic solvents. Lavsan holds another record. Its electrical resistivity is from 10 to 10 Ohm m, which is higher than all other substances. It is these figures that are "guilty" of the fact that the world production of fibers has exceeded 6 million tons per year.

Polyacrylonitrile fibers have increased weather resistance and the greatest resistance to strong acids. They are widely used in the production of carpets, furs, tarpaulins, upholstery and filter materials.

In terms of mold resistance, there is no equal to polycaproamide fiber. And polyvinyl alcohol and polyvinyl chloride fibers, which have found sufficient distribution in practice, differ from other synthetic materials in that they are absolutely not amenable to any destructive action of microorganisms.

Through the joint efforts of specialists from the Moscow Research Institute of Automotive Materials, the Ivanovo Iskozh Plant and the Ivanovo Research Institute of Film Materials, in the mid-80s, new material"Teza-M". This - synthetic fabric placed between layers of PVC film. The most important thing is that this material is not afraid of fire, water, or severe frosts. They do not sew from it, but weld various products, primarily awnings for KamAZ trucks.

Polyamide fibers have the highest impact resistance and extremely low hygroscopicity. Their value increases due to both high strength, elasticity and wear resistance. And polyundecanamide fiber from this class of polymers has one of the best electrical insulation values.

French researchers led by J.-M. Len in the mid-80s created ultrafine structure electrically conductive materials. The thickness of these thinnest conductors of electric current in diameter is much thinner than a human hair. The length of the molecular chain is sufficient to penetrate the entire double lipid layer of the membrane. Similar electron filaments at the molecular scale can be used as coupling elements in microelectronics.

Of all the common synthetic materials, polyurethane fiber demonstrates the greatest extensibility. Its relative elongation is 500-700%, that is, this fiber is able to stretch like rubber threads, and besides, it has even higher strength, wear resistance, elastic recovery and a smaller thickness. Therefore, it is indispensable in the production sportswear, bathing, corset and other products.

Japanese experts in 1982 created a new synthetic fiber with unusual properties: clothes made from it can protect a person from neutron radiation. This achievement was the answer of progressive scientific thought to the creation of a neutron bomb in the USSR and the USA.

And overalls and technical fabrics made from other synthetic fibers are extremely resistant to gamma radiation. This is polycarbonate fiber.

Poly-m-phenylene isophthalamide, which is produced commercially under the name phenylone, is most resistant to ionizing radiation. In addition, this material is one of the most thermally resistant. Therefore, it finds application in the production of special high-strength plastics and heat-resistant fibers.

Introduction.

Chemical fibers, fibers obtained from organic natural and synthetic polymers. Depending on the type of feedstock, chemical fibers are divided into synthetic (from synthetic polymers) and artificial (from natural polymers). Sometimes chemical fibers also include fibers obtained from inorganic compounds (glass, metal, basalt, quartz). Chemical fibers are produced in industry in the form of: 1) monofilament (single fiber of great length); 2) staple fiber (short lengths of thin fibers); 3) filament threads (a bundle consisting of a large number of thin and very long fibers connected by twisting). Filament threads, depending on the purpose, are divided into textile and technical, or cord threads (thicker threads of increased strength and twist).

History reference.

The possibility of obtaining chemical fibers from various substances (glue, resins) was predicted as early as the 17-18 centuries, but only in 1853 the Englishman Oudemars first suggested forming endless thin threads from a solution of nitrocellulose in a mixture of alcohol and ether, and in 1891 the French engineer I. de Chardonnay was the first to organize the production of such threads on an industrial scale. Since that time, the rapid development of the production of chemical fibers began. In 1893, the production of copper ammonia fiber from cellulose solutions in a mixture of aqueous ammonia and copper hydroxide was mastered. In 1893, the Englishmen Cross, Beaven and Beadle proposed a method for obtaining viscose fibers from aqueous alkaline solutions of cellulose xanthate, carried out on an industrial scale in 1905. In 1918-20, a method was developed for the production of acetate fiber from a solution of partially saponified cellulose acetate in acetone, and in 1935, the production of protein fibers from milk casein was organized. The production of synthetic fibers began with the release of polyvinyl chloride fiber (Germany) in 1932. In 1940, the most famous synthetic fiber, polyamide (USA), was produced on an industrial scale. Production on an industrial scale of polyester, polyacrylonitrile and polyolefin synthetic fibers was carried out in 1954-60.

Properties.

Chemical fibers often have high tensile strength (up to 1200 Mn/sq. m (120 kgf/sq. mm)), significant elongation at break, good dimensional stability, crease resistance, high resistance to repeated and alternating loading, resistance to light, moisture, mold, bacteria, chemo, and heat resistance. Physical-mechanical and physico-chemical properties of chemical fibers can be changed in the processes of forming, stretching, finishing and heat treatment, as well as by modifying both the feedstock (polymer) and the fiber itself. This makes it possible to create, even from one initial fiber-forming polymer, chemical fibers with a variety of textile and other properties (see table No. 1). Man-made fibers can be used in blends with natural fibers in the manufacture of new ranges of textiles, greatly improving the quality and appearance the latter.

Production.

For the production of chemical fibers from a large number of existing polymers, only those are used that consist of flexible and long macromolecules, linear or slightly branched, have a sufficiently high molecular weight and have the ability to melt without decomposition or dissolve in available solvents. Such polymers are commonly referred to as fiber-forming. The process consists of the following operations: 1) preparation of spinning solutions or melts; 2) fiber spinning; 3) finish molded fiber.

Preparation of spinning solutions (melts). This process begins with the transfer of the original polymer into a viscous state (solution or melt). Then the solution (melt) is cleaned of mechanical impurities and air bubbles and various additives are introduced into it for thermal or light stabilization of the fibers, their matting, etc. The solution or melt prepared in this way is fed to the spinning machine for spinning fibers.

Fiber spinning consists in forcing the spinning solution (melt) through the small holes of the spinneret into a medium that causes the polymer to solidify in the form of fine fibers. Depending on the purpose and thickness of the formed fiber, the number of holes in the spinneret and their diameter can be different. When forming chemical fibers from a polymer melt (for example, polyamide fibers), the medium that causes the polymer to harden is cold air. Its formation is carried out from a polymer solution in a volatile solvent (for example, for acetate fibers), such an environment is hot air, in which the thickness and purpose of the fibers, as well as the method of formation. During melt spinning, the solvent evaporates (the so-called "dry" molding process). When spinning a fiber from a polymer solution in a non-volatile solution (for example, viscose fiber), the filaments harden, falling after the spinneret into a special solution containing various reagents, the so-called precipitation bath (“wet” spinning method). The molding speed depends on the speed reaches 600-1200 m/min, from the solution by the "dry" method - 300-600 m/min, by the "wet" method - 30-130 m/min. The spinning solution (melt) in the process of turning streams of viscous liquid into thin fibers is simultaneously drawn out (spunbond drawing). In some cases, the fiber is additionally drawn directly after exiting the spinning machine (astification draw), which leads to an increase in the strength of the man-made fibers and an improvement in their textile properties.

Chemical fiber finishing consists in the treatment of freshly spun fibers with various reagents. The nature of the finishing operations depends on the spinning conditions and the type of fiber. At the same time, low molecular weight compounds (for example, from polyamide fibers), solvents (for example, from polyacrylonitrile fibers) are removed from the fibers, acids, salts and other substances entrained by the fibers from the precipitation bath (for example, viscose fibers) are washed off. To give the fibers such properties as softness, increased slip, surface adhesion of single fibers and others, after washing and cleaning, they are subjected to aviation treatment or oiling. The fibers are then dried on drying rollers, cylinders or drying chambers. After finishing and drying, some chemical fibers are subjected to additional heat treatment - heat fixation (usually in a taut state at 100-180 ° C), as a result of which the shape of the yarn is stabilized, and the subsequent shrinkage of both the fibers themselves and products from them during dry and wet treatments at elevated temperatures.

The world production of chemical fibers is developing rapidly. This is due, first of all, to economic reasons (less labor and capital investments) and the high quality of chemical fibers compared to natural fibers.

In 1968, the world production of chemical fibers reached 36% (7.287 million tons) of the volume of production of all types of fibers. Chemical fibers in various industries are largely replacing natural silk, linen and even wool. By 1980, the production of chemical fibers reached 9 million tons. It is assumed that by the year 2000 it will reach 20 million tons per year and will be equal to the volume of production of natural fibers. In the USSR in 1966, about 467 thousand tons were produced, and in 1970 - 623 thousand tons.

artificial fibres.

Artificial fibers, chemical fibers obtained from natural organic polymers. to artificial fibers

These include viscose fibers, copper-ammonia fibers, acetate fibers, protein artificial fibers. Viscose and copper ammonia fibers, consisting of hydrated cellulose, are also called hydrated cellulose. The raw material for the production of viscose, copper-ammonia and acetate fibers is cellulose isolated from wood; copper ammonia and acetate fibers are often obtained from cotton cellulose (cotton fluff and down). To obtain protein fibers, proteins of plant or animal origin (for example, zein, casein) are used. Artificial fibers are formed from polymer solutions by dry or wet methods and are produced in the form of textile or cord threads, as well as staple fibers. The disadvantages of viscose, copper-ammonia and protein fibers include a significant loss of strength in the wet state and easy creasing. However, due to good hygienic properties, low cost and availability of raw materials, the production of viscose fiber continues to develop. The production of acetate fibers, which have a number of valuable qualities (non-creasing, good appearance), is also growing. Protein fibers are produced in small quantities, and their release gradually decreases.

World production of artificial fibers in 1968 amounted to 3527.2 thousand tons (about 48.4% of the total output of chemical fibers). For the first time, the production of artificial fibers on an industrial scale was organized in 1891 in France.

Synthetic fibres.

Synthetic fibers, chemical fibers obtained from synthetic polymers. Synthetic fibers are formed either from a polymer melt (polyamide, polyester, polyolefin) or from a polymer solution (polyacrylonitrile, polyvinyl chloride, polyvinyl alcohol) using a dry or wet method.

Synthetic fibers are produced in the form of textile and cord threads, monofilament, and staple fiber. The variety of properties of the initial synthetic polymers makes it possible to obtain synthetic fibers with different properties, while the possibilities for varying the properties of artificial fibers are very limited, since they are formed from practically one polymer (cellulose and its derivatives). Synthetic fibers are characterized by high strength, water resistance, wear resistance, elasticity and resistance to chemicals. The production of synthetic fibers is developing at a faster pace than the production of artificial fibers. This is due to the availability of raw materials and the rapid development of the raw material base, less labor intensity production processes and especially the variety of properties and high quality of synthetic fibers. In this regard, synthetic fibers are gradually replacing not only natural, but also artificial fibers in the production of some consumer goods and technical products.

In 1968, the world production of synthetic fibers was 3760.3 thousand tons (about 51.6% of the total output of chemical fibers). For the first time, the production of synthetic fibers on an industrial scale was organized in the mid-30s of the 20th century in the USA and Germany.

Silk and staple fiber.

Artificial fiber can be obtained in the form of twisted threads of infinite length (artificial silk) or in the form of short untwisted fibers cut into bundles (staples) of a certain length (staple fiber). The length of the staple fiber is trimmed to the length of the cotton or wool fiber.

Artificial silk is an independent textile material that can be used for the manufacture of various textile products in weaving and knitwear, as well as for the manufacture of cord.

Staple fiber is mainly used in its pure form, as well as mixed with cotton or wool, and then goes through the entire cycle of operations with these fibers in the spinning mill. The conditions for the preparation of spinning solutions in the formation of silk and staple fibers are basically the same. For spinning staple fibers, spinnerets with a significantly larger number of holes are used than for spinning rayon. If for spinning rayon spinnerets with 24-100 holes are used, then when spinning staple fiber, the number of holes in the spinneret reaches 2000-12000, which leads to a significant increase in the productivity of the spinning machine.

Of the total produced in 1949 artificial fiber 61% was rayon and 39% was staple fiber. The cost of staple fiber is about two times lower than the cost of rayon. The question of the expediency of producing artificial silk or staple fiber is decided by the ratio of the capacity of spinning and weaving mills and the assortment of products produced.

The main indicators of the quality of artificial fiber are its strength and elasticity. The specific strength of a fiber is usually characterized by its breaking length in kilometers. The breaking length of the artificial fiber is 15-20 kilometers. The metric number determines the fineness of the fiber, that is, the number of meters of fiber in 1 gram. The thicker the fiber, the greater its titer, the lower the metric number. The elementary fiber of artificial silk has a metric number of 6000 - 3000, which corresponds to a fiber thickness of 20 - 40 microns. The fineness of rayon fibers is also often expressed in terms of denier titer. Titre is the weight of 9000 meters of fiber, expressed in grams. If 9,000 meters of fiber weighs 1 gram, then the fiber titer is 1 denier. The specific strength of the fiber is also expressed in grams per denier. The normal strength of viscose fiber is 1.8 - 2.2 grams per denier.

By changing individual parameters of the technological process and improving the quality of raw materials, the strength of the fiber can be increased by 2-3 times (obtaining the so-called high-strength artificial fiber), which is especially important when obtaining cord fiber.