Russian culture at the beginning of the 19th century.
First half of the 19th century was marked by significant progress in Russian culture, accompanied by the development of education, science, literature and art. It reflected both the growth of self-awareness of the people and the new democratic principles that were taking hold in Russian life during those years. Cultural influence increasingly penetrated the most diverse strata of society, coming into close contact with reality and meeting the practical requirements of social life.
Education
Socio-economic development of Russian society in the first half of the 19th century. insistently demanded fundamental changes in the field of public education. During the reign of Alexander I, an education system was created that included parish one-class schools and two-class district schools at the initial stage, followed by four-year gymnasiums, and, finally, higher education was based on study at universities and a few technical educational institutions.
The central links of this system were Russian universities (Moscow, Petersburg, Kazan, Dorpat, etc.). Along with them, there were noble class educational institutions - lyceums, the most famous of which was the Tsarskoye Selo Lyceum. Children of nobles received military education in cadet corps.
During these years, education in Russia made a significant step forward. If in the 18th century it remained the privilege of the highest noble circles, then already in the first quarter of the 19th century. became widespread among the nobility, and later among the merchants, petty bourgeoisie, artisans.
The number of libraries in the country has noticeably grown, among which many private ones have appeared. Newspapers and magazines began to arouse increasing interest among the reading public, the publication of which has noticeably expanded ("Northern Bee", "Gubernskie vedomosti", "Vestnik Evropy", "Son of the Fatherland", etc.).
Science and technology
In the first half of the 19th century. Russian science has achieved significant success. Russian history was studied successfully. For the first time, the educated reader received an extensive, written in literary language, 12-volume "History of the Russian State", created in 1816-1829. N.M. Karamzin. A notable contribution to Russian medieval studies was made by T.N. Granovsky, whose lectures at Moscow University had a great public response.
Significant successes were achieved by Russian philologists, A.H. Vostokov became the founder of Russian paleography, Russian and Czech Slavic scholars worked in close collaboration.
In the first half of the 19th century. Russian sailors made about 40 voyages around the world, the beginning of which was laid by the expeditions of IF Kruzenshtern and YF Lisyansky on the sailing ships "Nadezhda" and "Neva" (1803-1806). Undertaken in 1819-1821. FF Bellingshausen and MP Lazarev, an expedition to the South Pole on the sloops "Vostok" and "Mirny" discovered Antarctica. In 1845 ᴦ. the Russian Geographical Society began to work,
In 1839 ᴦ. Thanks to the efforts of V.Ya. Struve, the famous exemplary astronomical observatory was opened in Pulkovo (near St. Petersburg), equipped with the largest telescope.
The works of Russian mathematicians: V.Ya.Bunyakovskiy, M.V. Ostrogradskiy have become world-famous. A significant contribution to the development of mathematics was the creation by N.I. Lobachevsky of the so-called non-Euclidean geometry.
Russian physicists worked successfully in the field of electricity. VV Petrov discovered the electric arc (1802), which was of great practical importance, and studied the problems of electrolysis. The works of E.H. Lenz were devoted to the conversion of thermal energy into electrical energy, P.L. Schilling was the creator of the electromagnetic telegraph (1828-1832). Subsequently, in 1839 ᴦ. another Russian physicist B.S. Jacobi connected the capital with Tsarskoe Selo by an underground cable. Jacobi also worked a lot and successfully on the creation of an electric motor; a boat with such an engine was tested on the Neva. In the workshop of Jacobi, another of his discoveries was used - electroplating, sculpture, copper bas-reliefs were made, which, in particular, was used to decorate St. Isaac's Cathedral in St. Petersburg.
Metallurgist P.P. Anosov worked on the study of the structure of metals, chemist N.N. Zinin managed to obtain aniline dyes from benzene, biologists K.Ber and K.Rulier were world famous. Russian doctors began to use anesthesia during operations (N.I. Pirogov used painkillers and antiseptics in the field), worked in the field of blood transfusion (A.M. Filomafitsky).
Achievements in the field of technology were also significant. Its development contributed to the industrial revolution in Russia. In 1834 ᴦ. at the Vyysky plant (Ural), serf mechanics, father and son E.A. and M.E. Cherepanovs built one of the first railways in the world, and already in 1837 ᴦ. the first trains went along the St. Petersburg - Tsarskoe Selo railroad. The first steamships on the Neva appeared in 1815 ᴦ., And in 1817-1821. they began to swim along the Kama and Volga.
Literature
Russian literature of the first half of the 19th century. - one of the most striking phenomena in the history of world culture. At the turn of the XVIII-XIX centuries. classicism with its rhetoric and "high calmness" was gradually replaced by a new literary trend - sentimentalism. The founder of this trend in Russian literature was N.M. Karamzin. His works, opening up the world of human feelings to contemporaries, enjoyed great success. The creativity of N.M. Karamzin played an important role in the development of the Russian literary language. It was NM Karamzin, in the words of VG Belinsky, who transformed the Russian language, taking it off the stilt of the Latin construction and heavy Slavicism and brought it closer to the living, natural, colloquial Russian speech. "
The Patriotic War of 1812, the rise of national consciousness generated by it, gave rise to such a literary trend as romanticism. V.A. Zhukovsky became one of its most prominent representatives in Russian literature. In his works, V.A. Zhukovsky often turned to plots inspired by folk art, shifting legends and fairy tales with verses. Zhukovsky's active translation activities introduced Russian society to the masterpieces of world literature - the works of Homer, Ferdowsi, Schiller, Byron, and others.
Posted on ref.rf
The revolutionary romanticism of the poets - the Decembrists K.F. Ryleev, V.K. Küchelbecker - was permeated with high civic pathos.
Russian literature of the first half of the 19th century. unusually rich in bright names. The greatest manifestation of folk genius was the poetry and prose of A.S. Pushkin. "... through the era of Derzhavin, and then Zhukovsky," wrote one of the outstanding representatives of Russian philosophical thought, V.V. Zenkovsky, "Pushkin comes, in which Russian creativity took its own path - not alienating the West ... but already linking himself in freedom and inspiration with the very depths of the Russian spirit, with the Russian element. " In the 30s of the XIX century. the talent of the younger contemporary of A.S. Pushkin, M.Yu. Lermontov, flourished in a magnificent color. Having embodied in his poem "On the death of a poet" the nationwide grief over the death of A.S. Pushkin, M.Yu. Lermontov soon shared his tragic fate. The work of A.S. Pushkin and M.Yu. Lermontov is associated with the assertion of a realistic direction in Russian literature.
This trend found its vivid embodiment in the works of Nikolai Gogol. His work has left a huge imprint on the further development of Russian literature. The strong influence of N.V. Gogol was experienced by those who began their literary activity in the 40s of the XIX century. F.M.Dostoevsky, M.E.Saltykov-Shchedrin, N.A.Nekrasov, I.S.Turgenev, I.A.Goncharov, whose names are the pride of national and world culture. A major event in the literary life of the late 30s - early 40s was the short creative activity of A.V. Koltsov, whose poetry went back to folk songs. The philosophical and romantic lyrics of the outstanding poet and thinker F.I. Tyutchev were saturated with a deep sense of the Motherland. The elegies of E.A. Baratynsky became the masterpieces of the Russian national genius.
A significant phenomenon in the cultural life of Russia in the first half of the 19th century. became a theater.
Posted on ref.rf
The popularity of theatrical art grew. The serf theater was replaced by the "free" theater - state and private. However, state theaters appeared in capital cities as early as the 18th century. In particular, in St. Petersburg at the beginning of the XIX century. there were several of them - the palace theater in the Hermitage, the Bolshoi and Maly theaters. In 1827 ᴦ. a circus was opened in the capital, where not only circus performances were staged, but also dramatic performances. In 1832 ᴦ. In St. Petersburg, according to the project of K.I. Rossi, a building of a drama theater was built, equipped with the latest theatrical technology. In honor of the wife of Nicholas I, Alexandra Feodorovna, it became known as the Alexandria Theater (now the A.S. Pushkin Theater). In 1833 ᴦ. the construction of the Mikhailovsky Theater (now the Maly Opera and Ballet Theater) was completed. It received its name in honor of the brother of Nicholas I - Grand Duke Mikhail Pavlovich. In Moscow in 1806 ᴦ. the Maly Theater was opened, and in 1825 ᴦ. the construction of the Bolshoi Theater was completed.
Such dramatic works as "Woe from Wit" by A.S. Griboyedov, "The Inspector General" by N.V. Gogol and others were shown with great success.
Posted on ref.rf
In the early 50s of the XIX century. the first plays by A.N. Ostrovsky appeared. In the 1920s and 1940s, the outstanding Russian actor M.S. Shchepkin, a friend of A.I. Herzen and N.V. Gogol, demonstrated his multifaceted talent in Moscow. Other remarkable artists also enjoyed great success with the public - V.A. Karatygin, the premier of the capital's stage, P.S. Mochalov, who reigned on the stage of the Moscow Drama Theater, and others.
Significant successes in the first half of the 19th century. achieved the ballet theater, whose history at that time was largely associated with the names of the famous French directors Didlot and Perrot. In 1815 ᴦ. A wonderful Russian dancer A.I. Istomina made her debut on the stage of the Bolshoi Theater of St. Petersburg.
First half of the 19th century became the time of the formation of a national music school in Russia. In the same period, a Russian national opera was created. The work of M.I. Glinka made a huge contribution to the development of musical art. The operas A Life for the Tsar created by him (for obvious reasons it was called Ivan Susanin for a long time in our country), Ruslan and Lyudmila put Mikhail Glinka on a par with the world's largest composers. In his opera and symphonic work, M.I. Glinka was the founder of Russian classical music. Among the most talented composers of the first half of the 19th century. included A.A. Alyabyev - the author of more than 200 romances and songs, A.N. Verstovsky. A major phenomenon in the history of Russian musical art was the work of A.S. Dargomyzhsky. His vocal works, especially romances, were very successful. Based on songs and ceremonies, his opera "Mermaid" was created - a lyrical musical drama. The treasury of Russian musical art includes the opera by A.S.Dargomyzhsky "The Stone Guest", written to the text of A.S. Pushkin.
Painting. Trends in Russian painting XIX
Cultural life of Russia in the first half of the 19th century. characterized by the intensive development of the fine arts. Arose in Russian painting back in the 18th century. classicism proclaimed antique art as a role model. In the second quarter of the XIX century. it is expressed in academism, adopted by the Academy of Arts as the only art school. Conserving classical forms, academicism brought them to the level of an immutable law and was a "government direction" in the visual arts. The representatives of academicism were F.A. Bruni, I.P. Martos, F.I. Tolstoy.
Since the beginning of the XIX century. in Russian fine arts such a direction as sentimentalism is developing. However, elements of sentimentalism in the work of Russian masters were usually combined with elements of classicism or romanticism. The features of sentimentalism were most fully embodied in the works of the remarkable artist A.G. Venetsianov, who lovingly painted Central Russian village landscapes and portraits of peasants. The romantic direction of painting was embodied in the work of K.P. Bryullov, perhaps the most famous Russian artist of the first half of the 19th century. His painting "The Last Day of Pompeii" aroused the delight of his contemporaries and brought KP Bryullov European fame. O.A. Kiprensky was a striking representative of the romantic trend. Having lived a short, but exceptionally rich creative life, in his paintings he was able to express such the best human feelings and ideas as patriotism, humanism, love of freedom. 30-40s of the XIX century became the time of the birth of a new direction in Russian painting - realism. P.A. Fedotov became one of its founders. The characters of P.A. Fedotov were not heroes of antiquity, but ordinary people. He became the first artist to raise the theme of the "little man", which later became traditional for Russian art.
A significant phenomenon in the artistic life of Russia in the first half of the 19th century. was the work of A.A. Ivanov, the outstanding marine painter I.K. Aivazovsky. AA Ivanov devoted many years to work on the gigantic canvas "The Appearance of Christ to the People", having put into it a deep philosophical and ethical content. The noble ideas of goodness and justice, intolerance of violence and vices, which inspired Russian artists in the first half of the 19th century, had a strong influence on the development of Russian fine arts in the following decades.
Architecture
The development of Russian urban planning in the first half of the 19th century. stimulated the creative search of Russian architects. The main focus was still on construction in St. Petersburg. It was during this period that the classic look, traditional for him, was formed. A number of monumental ensembles are being created in the city in the style of mature classicism. In the center of the capital, on Palace Square, K.I. Rossi erects the General Staff building (1819-1829), a little later, according to the design of O. Montferrand, the Alexander Column (1830-1834) was installed here, and in 1837-1843. A.P. Bryullov is building the building of the Headquarters of the Guards Corps. The same Rossi in 1829-18E4. creates the buildings of the Senate and Synod, the Mikhailovsky Palace (1819-1825), the Alexandria Theater and builds up an entire street (Teatralnaya, now Zodchego Rossi Street). In the first decade of the 19th century. in St. Petersburg, the Smolny Institute (D. Quarenghi), the building of the Stock Exchange with Rostral columns (Toma de Tomon), the Kazan Cathedral (A.N. Voronikhin) are under construction. In subsequent years, St. Isaac's Cathedral (O. Montferrand), the Main Admiralty (A.D. Zakharov) were erected.
Stone construction was going on in other cities of the empire. After the fire 1812 ᴦ. Moscow was quickly rebuilding. In provincial and district cities, along with stone buildings, private large stone houses began to be built.
Russian culture at the beginning of the 19th century. - concept and types. Classification and features of the category "Russian culture at the beginning of the XIX century." 2017, 2018.
These are fibers obtained from organic natural and synthetic polymers. Depending on the type of raw material, 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) monofilaments (single fiber of long length);
2) staple fiber (short lengths of fine fibers);
3) filament yarns (a bundle consisting of a large number of thin and very long fibers, connected by twisting), filament yarns, depending on the purpose, are divided into textile and technical, or cord yarns (thicker yarns of increased strength and twist).
Man-made fibers - fibers (threads) obtained by industrial methods in a factory.
Chemical fibers, depending on the feedstock, are divided into main groups:
artificial fibers are obtained from natural organic polymers (for example, cellulose, casein, proteins) by extracting polymers from natural substances and chemical action on them
synthetic fibers are produced from synthetic organic polymers obtained by synthesis reactions (polymerization and polycondensation) from low-molecular compounds (monomers), the feedstock for which are products of oil and coal
mineral fibers - fibers obtained from inorganic compounds.
Historical reference.
The possibility of obtaining chemical fibers from various substances (glue, resins) was predicted as early as the 17th and 18th centuries, but it was not until 1853 that the Englishman Oudemars first proposed 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 man-made fibers began. In 1896 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, Beavin and Beadl proposed a method for producing 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 production was organized protein fibers from milk casein.
In the photo on the right below - not chemical fiber, of course, but cotton fabric.
The production of synthetic fibers began with the release in 1932 of polyvinyl chloride fiber (Germany). In 1940, the most famous synthetic fiber, polyamide (USA), was produced on an industrial scale. Industrial production of polyester, polyacrylonitrile and polyolefin synthetic fibers took place in 1954-60. Properties. Chemical fibers often have high tensile strength [up to 1200 MN / m2 (120 kgf / mm2)], significant tensile elongation, good dimensional stability, crease resistance, high resistance to repeated and alternating loads, resistance to light, moisture, mold, bacteria, chemo heat resistance.
The physicomechanical and physicochemical 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 chemical fibers with a variety of textile and other properties even from one initial fiber-forming polymer (table). Chemical fibers can be used in mixtures with natural fibers in the manufacture of new assortments of textiles, significantly improving the quality and appearance of 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 weakly 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 polymers. The process consists of the following operations: 1) preparation of spinning solutions or melts; 2) fiber forming; 3) finishing of the spun fiber. The preparation of spinning solutions (melts) begins with the transfer of the initial 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 fibers, their matting, etc. The solution or melt prepared in this way is fed to the spinning machine to spin the fibers. Fiber spinning involves forcing a dope (melt) through the fine holes of the spinneret into an environment that solidifies the polymer into fine fibers.
Depending on the purpose and thickness of the fiber being formed, the number of holes in the die and their diameter can be different. When chemical fibers are spun from a polymer melt (for example, polyamide fibers), cold air serves as a medium that solidifies the polymer. If spinning is carried out from a solution of the polymer in a volatile solvent (for example, for acetate fibers), this medium is hot air in which the solvent evaporates (the so-called "dry" spinning process). When a fiber is spun from a polymer solution in a non-volatile solvent (for example, rayon fiber), the filaments solidify, falling after the spinneret into a special solution containing various reagents, the so-called precipitation bath ("wet" spinning method). The spinning speed depends on the thickness and purpose of the fibers, as well as on the spinning method.
When molded from a melt, the speed reaches 600-1200 m / min, from a 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 converting streams of viscous liquid into thin fibers is simultaneously drawn (spinneret drawing). In some cases, the fiber is additionally stretched immediately after leaving the spinning machine (plasticizing drawing), which leads to an increase in the strength of V. x. and improving their textile properties. The finishing of chemical fibers consists in the processing of freshly formed 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 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 out. To impart such properties to the fibers as softness, increased slip, surface adhesion of single fibers, etc., after washing and cleaning, they are subjected to avivage treatment or oiling. The fibers are then dried on drying rollers, cylinders or drying chambers. After finishing and drying, some chemical fibers undergo additional heat treatment - heat setting (usually in a taut state at 100-180 ° C), as a result of which the yarn shape is stabilized, and the subsequent shrinkage of both the fibers themselves and products made from them during dry and wet treatments at elevated temperatures.
Lit .:
Characterization of chemical fibers. Directory. M., 1966; Rogovin Z.A., Fundamentals of chemistry and technology for the production of chemical fibers. 3rd ed., Vol. 1-2, M.-L., 1964; Chemical fiber production technology. M., 1965. V.V. Yurkevich.
as well as other sources:
Great Soviet Encyclopedia;
Kalmykova E.A., Lobatskaya O.V. Materials science of sewing production: Textbook. Allowance, Minsk: Vysh. shk., 2001412s.
Maltseva E.P., Materials science of garment production, - 2nd ed., Revised. and additional Moscow: Light and food industry, 1983,232.
Buzov B.A., Modestova T.A., Alymenkova N.D. Materials science of sewing production: Textbook. for universities, 4th ed., revised and enlarged., M., Legprombytizdat, 1986 - 424.
By chemical composition, fibers are subdivided on organic and inorganic fibers.
Organic fibers are formed from polymers containing carbon atoms directly connected to each other, or including atoms of other elements along with carbon.
Inorganic fibers are formed from inorganic compounds (compounds from chemical elements other than carbon compounds).
For the production of chemical fibers from a large number of existing polymers, only fiber-forming polymers are used. Fiber-forming polymers consist of flexible and long macromolecules, linear or weakly branched, have a sufficiently high molecular weight and have the ability to melt without decomposition or dissolve in available solvents.
Natural and man-made fibers ……………………………………… ... …… .3
Scopes of chemical fibers ……………. ……………………… ..5
Classification of chemical fibers ……………………………………… ..… ..7
Managing the quality of chemical fibers ……………………. ………… ...… 9
Technological process for the production of chemical fibers …………… ...… ..10
Production flexibility …………………………………………… ... ………… ..14
List of used literature ………………………………………… ...… 15
Natural and chemical fibers
All types of fibers, depending on their origin, are divided into two groups - natural and chemical. Among the natural, organic (cotton, flax, hemp, wool, natural silk) and inorganic (asbestos) fibers are distinguished.
The development of the chemical fiber industry is in direct proportion to the availability and availability of basic raw materials. Wood, oil, coal, natural gas and refinery gases, which are the feedstock for the production of chemical fibers, are available in our country in sufficient quantities.
Chemical fibers have long ceased to be only substitutes for silk and other natural fibers (cotton, wool). At this time, they form a completely new class of fibers, which has an independent meaning. Chemical fibers can be used to make beautiful, durable and generally available consumer goods, as well as high-quality technical products that are not inferior in quality to products made from natural fibers, and in many cases surpass them in a number of important indicators.
In the textile and knitwear industry, chemical fibers are used both in pure form and in a mixture with other fibers. They are used to produce clothing, dress, lining, linen, decorative and upholstery fabrics; artificial furs, carpets, stockings, underwear, dresses, outerwear, knitwear and other products.
The rapid development of the production of chemical fibers is stimulated by a number of objective reasons:
a) the production of chemical fibers requires less capital investment for the production of a unit of output than the production of any type of natural fiber;
b) labor costs required for the production of chemical fibers are significantly lower than in the production of any kind of natural fibers;
c) chemical fibers have a variety of properties, which ensures high quality products. In addition, the use of man-made fibers makes it possible to expand the range of textiles. No less important is the fact that the properties of natural fibers can be changed only within very narrow limits, while the properties of chemical fibers, by varying the conditions of spinning or subsequent processing, can be purposefully changed over a very wide range.
Applications of chemical fibers
Depending on the purpose, chemical fibers are produced in the form of monofilaments, multifilaments, staple fibers and tows.
Monofilaments are single threads of great length, not dividing in the longitudinal direction and suitable for the direct manufacture of textiles and technical products. Monofilament is most often used in the form of fishing line, as well as for the manufacture of fishing nets and flour sieves. Sometimes monofilaments are also used in various measuring devices.
Complex threads - consist of two or more filaments, connected by twisting, gluing, and suitable for the direct manufacture of products. Complex yarns, in turn, are divided into two groups: textile and technical. Textile yarns include thin yarns intended primarily for the manufacture of consumer goods. Industrial yarns include yarns with a high linear density used for the manufacture of technical and cord products (auto and aircraft tires, conveyor belts, drive belts).
Recently, complex yarns of high tensile strength and with minimal deformation under loading (high modulus) have begun to be widely used for reinforcing plastics, and high-strength yarns with special properties - for the manufacture of road surfaces.
Staple fiber, consisting of filaments of various cut lengths, until recently was used only for the manufacture of yarn on cotton, wool and linen spinning machines. Nowadays, fibers with a round cross-section are widely used for the manufacture of wall and floor carpets and the upper layer of interfloor floors. Fibers 2 - 3 mm long (fibrids) are used for making synthetic paper.
A rope, consisting of a large number of longitudinally folded filaments, is used to make yarn on textile machines.
For products of a certain assortment (outerwear, hosiery, etc.), textured threads are produced, which, by additional processing, are given increased bulk, crimp or extensibility.
All man-made fibers currently being produced can be divided into two groups in terms of production volume - high-tonnage and low-tonnage. Large-tonnage fibers and threads are intended for mass production of consumer goods and technical products. Such fibers are produced in large volumes on the basis of a small number of initial polymers (GC, LC, PA, PET, PAN, PO).
Low-tonnage fibers, or, as they are also called, special-purpose fibers, are produced in small quantities due to their specific properties. They are used in technology, medicine and a number of branches of the national economy. These include heat and heat resistant, bactericidal, fire resistant, chemisorption and other fibers. Depending on the nature of the initial fiber-forming polymer, chemical fibers are subdivided into artificial and synthetic.
Depending on the nature of the initial fiber-forming polymer, chemical fibers are subdivided into artificial and synthetic.
Classification of chemical fibers
Artificial fibers are produced on the basis of natural polymers and are subdivided into hydrated cellulose, acetate and protein. The most large-tonnage are hydrated cellulose fibers obtained by the viscose or copper-ammonia method.
Acetate fibers are obtained on the basis of cellulose acetate esters (acetates) with different contents of acetate groups (BAC and TAC fibers).
Fibers based on proteins of plant and animal origin are produced in very limited quantities due to their low quality and use for their production of food raw materials.
Synthetic fibers are produced from polymers synthesized in industry from simple substances (caprolactam, acrylonitrile, propylene, etc.). Depending on the chemical structure of the macromolecules of the initial fiber-forming polymer, they are divided into two groups: carbo-chain and hetero-chain.
Carbochain fibers include fibers obtained on the basis of a polymer, the main macromolecular chain of which is built only of carbon atoms connected to each other. The greatest application of this group of fibers is obtained by polyacrylonitrile and polyolefin fibers. To a lesser extent, but still in relatively large quantities, fibers are produced based on polyvinyl chloride and polyvinyl alcohol. Fluorinated fibers are produced in limited quantities.
Heterochain fibers include fibers obtained from polymers, the main macromolecular chains of which, in addition to carbon nitrogen, contain atoms of oxygen, nitrogen or other elements. Fibers of this group - polyethylene terephthalate and polyamide - are the most large-tonnage of all chemical fibers. Polyurethane fibers are produced in a relatively small volume.
Of particular note is the group of high-strength high-modulus fibers for technical purposes - carbon fibers obtained from graphitized or carbonized polymers, glass, metal or fibers obtained from metal nitrides or carbides. These fibers are mainly used in the manufacture of reinforced plastics and other structural materials.
Managing the quality of chemical fibers
Chemical fibers often have high breaking strength [up to 1200 MN / m2 (120kgf / mm2)], which means breaking elongation, good dimensional stability, crease resistance, high resistance to repeated and alternating loads, resistance to light, moisture, mold, bacteria, chemo and heat resistance. The physicomechanical and physicochemical 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 chemical fibers with a variety of textile and other properties even from one initial fiber-forming polymer. Man-made fibers can be used in blends with natural fibers to make new assortments of textiles, significantly improving the quality and appearance of the latter.
Technological process for obtaining chemical fibers
The technological process for the production of chemical fibers, as a rule, includes three stages. The only exception is the production of polyamide, polyethylene terephthalate and some other fibers, where the technological process begins with the synthesis of a fiber-forming polymer.
The first stage of the process is to obtain a dope or melt. At this stage, the original polymer is brought into a viscous state by dissolution or melting. In some cases (obtaining PVA fibers), the transition of the polymer to a viscous-flow state also occurs as a result of plasticization. The resulting spinning solution or melt is mixed and purified (filtration, de-aeration). At this stage, in order to impart certain properties to the fibers, various additives (heat stabilizers, dyes, matting agents, etc.) are sometimes introduced into the spinning solution or melt.
Chemical fibers are divided into artificial and synthetic
For the first time, artificial fibers were obtained at the end of the 19th century, although attempts to obtain them were much earlier. For example, glass threads were produced in ancient Egypt, they were used for jewelry, and in the middle of the 18th century. MV Lomonosov tried to find ways of their industrial production.
The group of artificial fibers includes viscose and acetate.
Scheme of obtaining fabric from artificial fibers:
Wood - spruce chips → Cellulose (in the form of sheets of cardboard) → Viscose preparation (liquid) → Forming fibers from solution → Textile processing of fibers (drawing, twisting, rewinding) → Weaving (fabric production) → Finishing production (fabric finishing)
1.Raw materials for viscose fiber production cellulose from spruce chips, waste cotton is used Cellulose sheets of cardboard are dissolved with caustic soda and, by treatment with other chemicals, a viscous viscose liquid is obtained, which is pushed through holes (spinnerets), from where thin continuous threads come out, and then textile processing of the fibers (drawing, twisting, rewind).
Viscose fibers are produced not only in the form of continuous threads, but also in the form of short lengths, i.e., staple fibers, suitable for the manufacture of both homogeneous viscose yarn, and mixed, with the addition of different fibers to impart various properties to fabrics.
Fabrics made of viscose fibers are used for sewing light clothes: linen, blouses, dresses, skirts, kerchiefs - and are used as lining and decorative (for curtains, curtains, bedspreads).
Fabrics made of viscose fibers have a beautiful appearance, they can resemble silk, wool, cotton, be matte or shiny, absorb moisture more than cotton.However, viscose fabrics lose about 50% of their wet strength, have a large shrinkage and wrinkle.
Products made from viscose fabric are washed with special detergents at a water temperature of 30 ... Ironed in a wet state at a temperature of 160 ... 180 0 С through an iron, sometimes dry cleaned.
Viscose fiber burns, like cotton, with a yellow, fast-running flame, having the smell of burnt paper; after combustion, gray ash remains.
2. Acetate fabrics are beautiful, have a slightly shiny surface, resemble silk in appearance and to the touch, light, soft, drape well, slightly wrinkled, retain their shape. The method for producing acetate fibers is the same as the method for producing viscose fiber. The only difference is that the cellulose produced from wood or cotton waste is treated with vinegar essence or sulfuric acid.
The disadvantage of acetate fabrics is the loss of strength when wet, they are poorly breathable and absorb moisture, and are difficult to iron.
Articles made of acetate fabrics are washed by hand in warm water at a temperature of 30 ° C with special detergents, dried in a suspended state on a hanger, ironed slightly damp, from the wrong side, through an iron with a warm iron.
Acetate fabrics dry quickly. Care must be taken with wet heat treatment and do not clean acetate fabrics with acetone, which will dissolve them.
Acetate fiber burns slowly, with a yellow flame, a melted ball and dark ash form at the end, a special sour smell is felt when burning.
3. Synthetic fibers obtained by synthesis - the reaction of combining simple substances (monomers), which are the product of processing of coal, oil and natural gas (phenol, acetylene, methane, etc.).
Synthetic fibers have a number of properties that natural fibers do not have: high mechanical strength, elasticity, resistance to chemicals, low creasing, poor flowability, poor shrinkage. All these properties are positive, therefore synthetic fibers are added to natural ones to obtain fabrics with improved quality.
The negative properties of synthetic fibers are reduced hygroscopicity, low air permeability, high electrification when worn, and therefore it is not recommended to wear clothes made of these fabrics for children and people with hypersensitivity to synthetic fibers.
The most common synthetic fiber fabrics include nylon, lavsan, nitron.
K and pro n - the most durable fiber to tear and abrasion.
Nylon fabrics are distinguished by their shine, high strength, easy to wash, dry quickly, and require careful wet heat treatment. Disadvantages of nylon fabrics - slipping, shedding, spreading of threads. Therefore, fabrics made of nylon threads are difficult to sew.
Lightweight fabrics, knitwear, lace, ribbons, braid are produced from nylon threads. In a mixture with other fibers, nylon fiber is used for the production of dress, costume, coat fabrics.
If the nylon fiber is brought to the flame, then it will begin to melt, and then ignite with a weak bluish-yellow flame with the release of white smoke. When cooled, a hard dark ball forms at the end.
Lavsan is a very strong and resilient fiber. It is blended with various fibers to increase the strength and elasticity of the fabric. In its pure form, lavsan is used for the manufacture of sewing threads, lace, technical fabrics, pile of artificial fur, carpets. From lavsan fibers mixed with wool, cotton, linen, viscose fiber, dress fabrics and knitwear are produced. Fabrics with lavsan are afraid of strong moisture and heat. In the flame, the lavsan threads first melt, then slowly burn with a yellowish flame, emitting black soot. After cooling, a hard black ball forms.
Nitron - the most persistent and "warm" fiber, fluffy, dull, resembles wool in appearance, therefore it is called "artificial wool" Nitron fiber fabrics are more durable and wear less than nylon and lavsan. Nitron fiber is used in the manufacture of knitwear (sweaters, jackets, scarves) and artificial fur with fluffy pile. From nylon fibers mixed with wool, viscose, cotton, dress and costume fabrics are produced. Nitron fibers burn in flashes, emitting black soot; after cooling, a solid ball is formed that can be crushed with your fingers.
2. You need to cook milk porridge for 3 people for breakfast. Using the recipe guide, determine the quantity, composition and approximate cost of products for the preparation of rice porridge, describe the technology of its preparation. Describe the importance of milk and dairy products in human nutrition (see appendix).
Cooking technology of milk rice porridge.
1. Primary processing of cereals: Sort the rice and rinse thoroughly in cold water.
- Introduction
- 1. Chemical fibers
- 1.2 Polyamide fibers
- 1.3 Polyester fibers
- 2.1 Synthesis of caprolactam
- 2.2 Synthesis of polycaproamide
- 3.5.1 Drawing the threads
- 3.5.2 Twisting the threads
- 3.5.3 Finishing the threads
- 3.5.4 Drying and conditioning the yarns
- 3.5.5 Rewinding the threads
- 3.5.6 Sorting threads
- 4. Examples of technological calculations
- Conclusion
- Bibliography
Introduction
For the first time, the idea that a person can create a process similar to the process of obtaining natural silk, in which a viscous liquid is produced in the body of a silkworm caterpillar, which solidifies in air to form a thin strong thread, was expressed by the French scientist R. Réaumur back in 1734. However, it took about a century and a half before this idea found its practical implementation.
Chemical fibers are called fibers, which are obtained using chemical or physicochemical processes for processing natural and synthetic high-molecular compounds (polymers). Depending on the origin of the polymer, chemical fibers are divided into two main groups: artificial fibers (if the polymer used is of natural origin) and synthetic (if the fiber-forming polymer is obtained as a result of chemical synthesis from low-molecular-weight monomer compounds).
In turn, the peculiarities of the chemical structure of fiber-forming polymers make it possible to divide chemical fibers into two main classes, carbon-chain fibers and hetero-chain fibers.
Heterochain fibers. This group includes all types of fibers obtained from various polyamides. Such fibers are polycaproamide, polyhexamethylene adipamide, polyenanthoamide, polyundecanamide, etc.
Heterochain fibers are the most widespread class of synthetic fibers. On an industrial scale, mainly two types of heterochain fibers are produced - polyamide and polyester - and, in small quantities, highly elastic polyurethane fiber.
The greatest distribution of polyamide fibers is explained by their inherent chain properties, a wide raw material base for their production. Also, to a large extent, the methods of obtaining the starting materials, as well as the processes of forming and subsequent processing, were developed for polyamide fibers earlier and in more detail than for other heterochain fibers.
Carbochain fibers. This class of synthetic fibers includes fibers whose macromolecules contain only carbon atoms in the main chain.
The produced carbon chain fibers are subdivided into polyacrylonitrile, polyvinyl chloride, polyvinyl alcohol, polyolefin and fluorine-containing.
Polyacrylonitrile fibers (nitron, orlon, etc.) are obtained from polymer and copolymers of acrylic acid nitrile.
Polyvinyl chloride fibers are produced from BX polymers and copolymers (roville fiber) and vinyldene chloride (soviden fiber, saran, etc.), as well as from chlorinated PVC (chlorin fiber).
Polyvinyl alcohol, polyolefin and fluorine-containing fibers are obtained, respectively, from polyvinyl alcohol (vinol fiber, curalon), polyolefins (polyethylene and polypropylene fibers) and fluorine-containing polymers (teflon fiber, fluorlon).
The important advantages of chemical fibers over natural fibers are a wide raw material base, high profitability of production and its independence from climatic conditions. Many man-made fibers also have better mechanical properties (strength, elasticity, wear resistance) and less wrinkle. The disadvantage of some chemical fibers, for example polyacrylonitrile, polyester, is low hygroscopicity.
1. Chemical fibers
1.2 Polyamide and polyester fibers
The fibers are mainly used for making clothing. In addition, a significant amount of them is spent on the manufacture of all kinds of technical fabrics and products, high-strength cord fabric, filter fabrics, fishing tackle, ropes, ropes, etc. Natural fibers are not enough to meet the ever-increasing needs of the population in textile products, and in many cases natural fibers are unsuitable for technical products, because they do not have the necessary complex of special properties (high heat resistance, strength, chemical resistance, biostability, etc.). Moreover, the production of natural fibers is very labor intensive and expensive. Therefore, it became necessary to develop industrial methods for artificial fiber production.
The production of chemical fibers, due to their high profitability and a huge raw material base, is growing very intensively. The rapid growth in the production of man-made fibers is largely due to their high characteristics.
The fastest growing production of synthetic fibers - polyamide (nylon, anid), polyester (lavsan), which explains their valuable properties (high strength in elasticity, resistance to repeated deformations, etc.), polyamide and polyester fibers are produced in the form of textile and high tenacity cords, fibers and monofilaments of various linear densities. Synthetic fibers are especially important for the production of certain types of technical products. For example, cord for aircraft and heavy duty pneumatic tires, electrical insulation materials, filter cloths for the chemical industry, etc. Also, high-strength threads or fabrics made of nylon and nylon are used to make the carcass of automobile and aviation rubber tires. These tires have increased durability and reliability.
1.2 Polyamide fibers
Polyamide fibers are synthetic fibers obtained from linear polymers, the macromolecules of which contain amide groups. Polyamide fibers made from aliphatic polyamides received wide industrial development. Macromolecules of these polyamides, along with amide groups, contain methylene groups.
Polycaproamide fibers molded from polycaproamide - a polymer, a polymer synthesized from caprolactam. These fibers are produced in different countries under various names, for example "nylon" (USSR), "dederon" (Germany), "nylon 6" (USA).
Polycaproamide is a solid white translucent product with a molecular weight of 15,000 - 25,000. At elevated temperatures in the presence of oxygen, polycaproamide undergoes degradation.
Polyhexamethylene adipamide fibers ("anid" (USSR), "nylon 6.6" (USA), etc.),. This polymer is obtained from the AG salt:
Polyenatoamide fibers ( enant (USSR), "nylon 7" (USA)) is formed from polyenantoamide - a polymer obtained by polycondensation of n - aminoenanthic acid.
Polyundecanamide fibers ( undecane, nylon 11, kiana), produced from polyundecanamide - a polyamide synthesized from
u - aminoundecanoic acid.
1.3 Polyester fibers
The name of this type of synthetic fiber is determined by the chemical nature of the polymer - complex polyester, from which these fibers are obtained. Complex polyesters include high-molecular substances with a general formula, the macromolecules of which consist of elementary units connected by an ester bond. This class includes both natural (amber, silk, etc.) synthetic polyesters. Polyester fibers based on polyethylene terephthalate (PET) are produced under the names Lavsan (USSR), Dacron (USA), Teteron (Japan), Terital (Spain).
PET is a solid, white, opaque substance that melts when heated. Upon rapid cooling of the polymer melt, a solid transparent product is formed, which crystallizes at a temperature above 80єС. The polymer is stable in many organic solvents (acetone, ethyl acetate, xylene, dioxane, etc.), but dissolves in phenols and their chlorine substituted ones. In alkalis and concentrated ammonia solutions, the polymer is destroyed.
Chemical fibers are mainly used for textile purposes and must be characterized by a very large length-to-diameter ratio (> 10,000), as well as peculiar mechanical properties. properties:
1) high strength (up to 1 Gn / m 2 (100 kgf / mm 2));
2) high relative elongation (> 5%);
3) elasticity and rapid disappearance of deformations arising under the influence of external forces;
4) minimal plastic (residual) deformations after removal of the load;
5) maximum resistance to multiple and alternating loads. Therefore, for the production of chemical fibers, only fiber-forming polymers are used as raw materials, which consist of flexible macromolecules of linear or weakly branched form with high molecular cohesion. The molecular weight of these polymers must be more than 15,000, and the molecular weight distribution is rather narrow. In addition, these polymers must melt without decomposition, dissolve in available solvents, or be rendered viscous in some other way.
Table 1. Comparative characteristics of the physical and mechanical properties of chemical and natural fibers
|
Density, kg / m 3 |
Equilibrium humidity,% |
Elongation at break,% |
Resistance to repeated bending, number of cycles |
Abrasion resistance (at a load of 3kPa) |
||||
|
Regular thread |
||||||||
|
Strong thread |
||||||||
|
Regular thread |
||||||||
|
Strong thread |
||||||||
|
Regular thread |
||||||||
|
Reinforced thread |
||||||||
|
Natural silk |
2. Production of nylon threads and fibers
The process of obtaining nylon threads and fibers has been well studied and is constantly being developed. The assortment of threads, designed to meet the needs of various sectors of the national economy, includes threads for textile and technological purposes.
There are three ways to produce nylon threads and fibers:
1) Batch method - batch or continuous synthesis of the polymer, batch processes of extraction and drying of crumbs (granules), the formation of complex filaments.
2) Continuous method with obtaining crumbs - continuous polymer synthesis, extraction and drying of crumbs, forming multifilament threads.
Continuous method with the formation of filaments directly from the melt (continuous polymer synthesis and spinning of filaments directly from the melt).
The first two methods for the production of nylon threads consist of the same technological stages, but the second method compares favorably with the first by using continuous processes of polymer synthesis, extraction and drying of crumb, which significantly improves the production technology and improves the quality of the polymer and threads.
The third method provides for the combination in a single technological process of a continuous method for producing a polymer with spinning of threads from a melt without re-melting of the polymer, while the technology of producing threads is radically changed. The continuous process has been fully implemented in the production of fibers and is increasingly used in the production of textile yarns.
2.1 Synthesis of caprolactam
Caprolactam can be synthesized from phenol, benzene, aniline, as well as from n-butane, furfural, acetylene, ethylene oxide and divinyl.
Consider an example of obtaining caprolactam from phenol:
Caprolactam production from phenol.
When phenol is hydrogenated (135-160 ° C) in the presence of a nickel catalyst, cyclohexanol is formed:
Dehydrogenation of cyclohexanol gives ketone-cyclohexanone:
The dehydrogenation reaction takes place at atmospheric pressure and a temperature of 400-450 ° C in the presence of an iron - zinc catalyst. When cyclohexanone reacts with hydroxylamine, cyclohexanone oxime (cyclohexanoxime) is formed. This process is called oximation. :
Oximation is carried out at 20 ° C. At the end of the process, when the liberated sulfuric acid is neutralized with ammonia, the temperature of the reaction mass spontaneously rises to 90 ° C.
Under the action of concentrated sulfuric acid, cyclohexanone oxime is isomerized in the lactam of aminocaproic acid (cyclohexanone isoxime), a rearrangement of atoms in the cyclohexanone oxime molecule occurs:
The caprolactam obtained in this way is purified from impurities by extraction with organic solvents (for example, trichlorethylene) and repeated distillation under vacuum.
The quality of caprolactam used for the production of nylon fiber is characterized by the following main indicators:
Appearance White crystals
Molecular weight 113.16
Temperature, єС
crystallization 68.8-69.0
boil 262
Permanganate number
3% aqueous solution, from 5000-10000
meq * / kg 0.0-0.6
Coloring a 50% aqueous solution,
units platinum-cobalt scale,
no more than 5.0
Cyclohexanone oxime 0.002
Iron 0.00002
Acidity meq / kg, no more than 0.2
Alkalinity meq / kg, no more than 0.05
Caprolactam arrives at synthetic fiber factories in polyethylene bags or in paper bags placed in rubberized fabric bags. It is also transported in a molten state in special tanks, covered with thermal insulation and equipped with a coil for steam heating. When transporting the caprolactam melt, a significant economic effect is achieved, since the operation of melting caprolactam at the consumer plant is eliminated and product contamination is eliminated. The molten lactam can be stored in heated and insulated containers.
2.2 Synthesis of polycaproamide
The process of polymerizing caprolactam - converting cycles into linear polymers - is called polyamidation. It takes place only at a relatively high temperature and elevated, normal or reduced pressure in the presence of an activator.
Activators can be organic or mineral acids, as well as water, AG salt, aminocaproic acid, or other compounds that, under the conditions of the caprolactam polyamidation process, are capable of undergoing chemical transformations with the release of water.
In addition to the listed compounds, alkalis and metallic sodium are very effective activators, which reduce the duration of the polyamidation reaction by tens and hundreds of times. In industrial conditions, water is most often used as an activator for the polyamidation of caprolactam.
The reaction mechanism for the formation of polycaproamide depends on the nature of the activator used. In the presence of water, the polyamidation reaction of caprolactam proceeds stepwise according to the following scheme:
At the initial stage of the process, when caprolactam interacts with water, aminocaproic acid is formed:
Aminocaproic acid combines with the caprolactam molecule to form a dimer:
The dimer interacts with another caprolactam molecule and a trimer is formed:
The addition of caprolactam molecules occurs before the formation of polycaproamide:
The polyamidation reaction of caprolactam is equilibrium and reversible:
In this regard, caprolactam is not completely converted into polycaproamide and the polymer always contains a certain amount of monomer and other low molecular weight water-soluble compounds (dimer, trimer and caprolactam).
The amount and composition of the low molecular weight fraction contained in the polycaproamide (Fig. 1) depends on the temperature conditions of the process. For example, at 180 ° C the amount of low molecular weight fractions consisting of a dimer and a trimer reaches 2-3%, and at 250-270 ° C it is already 10-12%, with about 2/3 of the monomer and 1/3 of the dimers and caprolactam trimers. Low molecular weight water-soluble compounds can be removed from polycapramide by hot water extraction or vacuum stripping from molten polymer.
Schedule 1 - Addiction the content of low molecular weight compounds in polycaproamide from polyamidation temperature caprolactam.
Certain requirements are imposed on polycaproamide intended for processing into nylon fiber. In particular, it must have a sufficiently high molecular weight (at least 11000) and be monolithic, i.e. do not contain a large number of voids and shells. In addition, the polymer should be free of oxidation products (white polycaproamide).
An important indicator of the fiberizing ability of polycaproamide is the molecular weight or degree of polyamidation.
The specified molecular weight of the polymer can be achieved by adjusting the polyamidation conditions - temperature, process duration and regulator (stabilizer) content. The regulators of the molecular weight of polyamides are substances capable of interacting with one of the end groups of the growing chain of a macromolecule during polymer synthesis, stopping its growth. Most often, acetic, sebacic or adipic acids are used as a regulator. For these purposes, acetic acid is also used. n-butylamine is a double-acting regulator capable of blocking both functional groups of a polyamide macromolecule.
By varying the amount of regulator added, a polymer with the desired molecular weight can be obtained. The more regulator added to the monomer, the lower the molecular weight of the polymer.
The fiber-forming ability of polycaproamide depends on such parameters of the polymer as solidity and the content of oxidation products. The presence of bubbles of gaseous products (most often water vapor) in the molten polymer is the reason for the breakage of the thread during spinning and drawing. Partial (the presence of dark spots) or continuous oxidation of polycaproamide (the polymer has a brown tint) also leads to breakage. In addition, when using such a polymer, sagging and non-elongated areas appear on the threads.
Oxidation of polycaproamide can be prevented by appropriate efforts of polyamidation of caprolactam, ensuring complete isolation of the reaction mass from the action of atmospheric oxygen.
3. Forming of fibers. Theoretical part
Fiber shaping. The process consists in forcing the spinning solution (melt) through the fine holes of the spinneret into an environment causing the polymer to solidify in the form of fine fibers. Depending on the purpose and thickness of the spun fiber, the number of holes in the die is:
1) 1? 4? for monofilament;
2) 10? 60? for textile threads;
3) 800? 1200? for cord threads;
4) 3000? 80000? for staple fiber. When molding man-made fibers from polymer melt of polyamide fibers the medium that causes the polymer to harden is cold air. If spinning is carried out from a solution of a polymer in a volatile solvent (e.g. acetate fibers), such a medium is hot air in which the solvent evaporates ("dry" molding process). When spinning from a solution of a polymer in a non-volatile solvent (eg rayon fibers), a solution containing various reagents, a so-called precipitation bath ("wet" spinning process), is used to precipitate the polymer and spin the fiber.
The spinning speed depends on the thickness and purpose of the fibers, as well as on the spinning method: for melt spinning - 10-20 m / sec, from solution by "dry" method - 5-10 m / sec, by the "wet" method - 0.5-2 m / sec.
The spinning solution (melt) in the process of converting streams of viscous liquid into fibers is simultaneously drawn (spinneret drawing), in some cases, the fiber is additionally drawn in the spinning shaft (settling bath) or immediately after leaving the spinning machine in a plastic state (plasticizing drawing). Pulling the fibers in a plastic state (orientation) increases their strength. After forming, the ropes containing from several to 360,000 fibers are sent for finishing or additionally drawn in a cold or heated (up to 100-160 ° C) form 3 × 10 times. Additional stretching significantly increases the tensile strength of the fibers and reduces their elongation. At the same time, many valuable textile properties of fibers are improved (the modulus of elasticity increases, the proportion of plastic deformation decreases, and resistance to multiple deformations increases). The spinning conditions (the rate of polymer solidification, the uniformity of its release from the solution or melt, the tension and the degree of elongation) determine the quality of the spun fibers and their physical and mechanical properties.
The equations describing the processes of flow of any fluids are the result of applying to the motion of these fluids the basic physical principles formulated in the laws of conservation of angular momentum, energy and mass.
These laws are formulated as follows: a productive element, separated inside a volume occupied by a moving fluid and bounded by an imaginary closed surface, is a thermodynamic closed system (i.e., a system that can only exchange energy with the environment).
It follows from the law of conservation of matter that the mass in a closed system remains constant. Mathematically, this law is expressed as follows:
where t is time, is the divergence of the velocity vector x.
In accordance with Newton's second law, the rate of change in the momentum of a fluid element is equal to the sum of all forces acting on it:
where g is the principal vector of mass forces acting on the fluid at the point under consideration.
However, taking into account that during the flow of polymers, due to their high viscosity, the friction forces are many times higher than the inertial and mass forces, the terms that take into account the influence of these forces are neglected. With this in mind, we simplify the equation and write it in the form:
Stokes equation.
The heat balance equation follows from the law of conservation of energy:
where C x is the specific heat capacity of the liquid at constant volume.
q - vector of heat flux,
k - coefficient of thermal conductivity of the liquid.
Mass conservation equations (continuity equations) in a rectangular coordinate system (x, y, z):
Mass conservation equations in cylindrical coordinates (r,?, Z):
Equations of motion in a rectangular coordinate system:
Equations of motion in a cylindrical coordinate system (r,?, Z):
In the stress tensor components, the first index indicates the direction of the normal to the site on which the given stress acts, the second index indicates the direction of stress action.
Due to the symmetry of the stress tensor, the following equalities are valid (the law of pairing of tangential stresses):
The above equations of motion do not describe the relationship between the magnitude of the shear stress and the corresponding strain rates. In order to fully characterize the behavior of the deforming polymer, it is necessary to supplement this equation with the rheological equation of state, connecting the components of the strain rate tensor with the components of the stress tensor.
From the rheological equation, which refers to the case of a steady one-dimensional flow.
The rheological equation of state, which takes into account the relaxation nature of the development of highly elastic deformation and is valid for small reverse deformations, has the form:
Note that the equations of state should be associated for a certain time interval not with any particular point in space with coordinates NS i, and with the same element of the environment located at the moment of time t at a point in space with coordinates NS i.
Recently, the formula of the rheological state for elastic-viscous medium proposed by White is also popular.
where pI is the isotropy component of the stress tensor.
Functional G can be represented as an integral expansion:
The rheological properties of the medium are determined by the appropriate choice of integral cores Ф and Ш. The first core Ф connects the relaxation modulus of linear viscoelasticity and limits the region of small deformation.
Using some instantaneous state of the environment as a reference point, it is possible to express a specific deformation of the environment using the Taylor series expansion:
where - e (s) = e (t - q) is the tensor of deformations, determined in accordance with the Fingler measure:
The simplest form of the rheological equation, taking into account the viscosity anomaly:
where I 2 is the quadratic invariant of the strain rate tensor,
m 0 - the value of the effective viscosity at I 2 =1.
The value of the quadratic invariant in rectangular coordinates:
The value of the quadratic invariant in cylindrical coordinates:
in the case of a simple shear, the rheological equation will take the form:
The energy balance equation, compiled for the steady state under the assumption that all thermophysical characteristics do not depend on temperature, has the form:
where c is the density of the melt, WITH p - heat capacity of the melt, k m- coefficient of thermal conductivity of the melt.
To build a model that admits an analytical solution, we make the following assumptions:
Axis flow y exists only in the immediate vicinity of the channel walls. In the rest of the channel section, the flow in the direction of the axis y absent.
The dimensions of the channel along the entire length are constant; therefore, the values x x and x z do not depend on z.
The temperature gradient in the transverse direction due to the circulating flow is negligible compared to the longitudinal gradient. Thus,
If the energy balance equation is assumed that the heat transfer due to heat conduction due to along the channel axis is negligible, then the energy balance equation will be reduced to the following form:
3.1 Forming multifilament yarns from the melt
The principle of forming filaments from a melt consists in forcing the polymer melt with a metering pump through the thin openings of the die. A stream of polymer melt leaving each hole of the spinneret, cooling in air, solidifies and turns into a filament. The filaments connected in a bundle form a complex thread, which is wound on a bobbin.
Dies are usually short capillaries with. The die channel has a smooth contour, which makes it possible to give the flow at the inlet a glass shape and minimize the distortion of the extrudate shape due to elastic recovery.
Picture 1 - Melt fiber spinning diagram
With an increase in the drawing speed and orientational stress, the value of the ratio D/ D 0 decreases rapidly. An approximate expression for evaluating the elastic recovery of the jet in the presence of a draft is as follows:
where, B= D/ D 0 - the coefficient of restoring the jet to the axial force,
F = 0, l eff is the relaxation time of macromolecules of the polymer melt,
m - conditionally fixed dynamic coefficient of viscosity,
G is the function describing the dissipation of the internal energy of the flow.
According to Oswald de Ville's power law, the equation for conservation of energy and momentum is as follows:
When considering the energy balance, the intensity of the heat flux due to the work of the forces of viscous friction, referred to the unit of volume (e v), is described by the expression:
Picture 2- Spinning place: 1 - crumb bunker; 2 - crane; 3 - compensator; 4 - branch pipe; 5 - melting grate; c - steam jacket; 7-molten polymer; 8-metering pump; 9 - pressure pump; 10 - pumping unit; 11 - die set; 12 - die; 13 - obtuchnaya mine; 14 - spinning shaft; 15 - preparative washers; 16 - pressure roller; 17 and 18 - spinning (foster) foxes; 19 - non-stacker; 20-spool; 21 - friction cylinder; 22 - thermal insulation.
For spinning filaments from a melt, a vertical pattern is characteristic when the filament moves from top to bottom. The machine for forming nylon threads is completed from a number of spinning positions. Each spinning position (Fig. 2) consists of three main units: a polycaproamide melting unit (crumbs) and a threading unit. Zones of solidification of melt streams and the formation of filaments and complex filaments. Devices for winding the spun yarn.
The unit for polymer melting and molding of melt streams consists of a hopper and a spinning head. A supply of crumbs is stored in the bunker in a nitrogen atmosphere, which is necessary for continuous operation for 2-6 days. Bunker? a vertical cylindrical vessel made of aluminum with a hatch in the upper part for loading crumbs and a conical bottom with a viewing glass for monitoring the consumption of crumbs (Fig. 3). A crane is mounted in the conical part of the hopper, which connects the hopper through an expansion joint and a branch pipe with a spinning head. Utilities for nitrogen supply and evacuation are connected to the upper part of the bunker. After loading the crumb and sealing the hopper, air is removed from it, for which a vacuum is alternately created several times and the hopper is filled with nitrogen.
Figure 3 - Spinning head:
1 - pipe branch; 2 - melting grate; 3 - metering pump; 4 - tepisolation; 5 - pump unit; 6 - head body; 7 - shirt; 8 - fneller set; 9 - sleevethermocouple; 10 - pressure pump.
The spinning head or melting-forming head consists of a heating jacket, a melting grate and a pumping unit. The melting grate (Fig. 4) is a flat, helical, tubular coil, heated from the inside by VOT vapors. Is the pump unit (fig. 5) equipped with two gear pumps? pressure head and metering (Fig. 6) and a spinneret set consisting of a filtering device (metal mesh and quartz sand) and a spinneret? massive plate with holes with a diameter of 0, 20 × 0.25 mm (for monofilament up to 0.5 mm). The melting grate and the pumping unit are located in the spinning head jacket, which is heated by steam or liquid heat exchanger from a common boiler room or by means of a local electric heater.
Drawing 4 - Melting grate: 1 - frame; 2 - coil.
From the hopper the crumbs by gravity through the tap, the compensator and the branch pipe are fed to the melting grate, where at 265-290 ° C the crumbs melt. The molten resin is collected in a conical space under the grate, from where it is taken by the injection pump and transferred to the metering pump. The dosing pump pumps the melt under excess pressure up to 8 MPa, forcing it through a filter and a die, from where it comes out in the form of thin uniform streams (Fig. 7).
Drawing 5 - Pump unit with melting grid.
Drawing 6 - Gear spinning (pressure head and metering) pump.
Drawing 7 - Spinning bottomth head with a blow-off shaft: 1 - spinning head end; 2 - blow-off shaft; 3 - a thread.
All parts of the spinning head (grate, block, pumps) with which the molten polymer comes into contact are made of alloyed heat-resistant steel.
To avoid oxidation of the polymer during melting, nitrogen is continuously blown over the melting grate, containing no more than 0.0005% oxygen. The amount of nitrogen supplied is strictly controlled, since an excess of nitrogen, even at the indicated oxygen content, causes oxidation of the polymer.
Along with those described, other designs of melting grates and spinning heads heated by liquid HOT and electricity are also used.
Figure 8 - Screw melter diagram (extruder):
1 - cylindrical vessel; 2 - boot device; 3 - electric heaters; 4 - screw; 5 - zonemelting; 6 - tempering zone; 7 - unloading area.
Another type of melting device is a screw melter - extruder (Fig. 8), which provides high productivity, minimum residence time of the polymer in the molten state, which leads to a minimal increase in the content of low molecular weight compounds in the polymer during the spinning process, intensive mixing of the melt, which is very important for homogenization its properties and creates sufficient pressure required to transport the melt to the spinning heads. Such a melting head enables the group of spinning heads to operate. A thread formed from crumb melted by means of extruders (containing 0.5 - 0.8% low molecular weight compounds and 0.05% moisture) contains up to 2% low molecular weight compounds that do not need to be extracted.
The zone of solidification of melt streams and the formation of filaments and filaments consists of a blowing and spinning (accompanying) shaft. The polymer melt streams emerging from the die holes solidify in the form of filaments, where they are combined into a bundle, forming a complex thread, which goes to the receiving and winding part of the machine.
The blowing chamber is located directly under the die and serves to create a uniform air flow in the direction perpendicular to the movement of the filaments. Due to this, the moving bundle of filaments (complex filament) is fixed in a certain position and the possibility of their oscillation and the formation of thinned and thickened sections is excluded. For blowing, conditioned air is used. From the blowing shaft, the filament goes into the spinning shaft, which serves to protect the spinning yarn from the influence of random air currents and for additional cooling in the case of spinning industrial yarns. For this purpose, the spinning shaft is jacketed for cooling with cold water.
3.2 Spun-off filament winding device
The yarns leaving the spinning shaft touch the dampening and lubricating devices (washers) and, passing through two spinning discs, enter the take-up reel, which is driven by a friction shaft.
The spinning discs serve for the convenience of threading and, in addition, contribute to a stable mode of spinning the yarn at a constant speed, preventing the vibrations of the filaments in the curing zone caused by the reciprocating movement of the yarn distributor.
The filaments exiting the spinning head are practically free of moisture; on the way from the spinneret to the take-up reel, the filament does not have time to be humidified by moisture in the air. To prevent the yarn on the spinning bobbin from getting wet during the winding process, which would cause the fiber to slip off the spool and damage it, it is moistened before it enters the bobbin. In addition, in the multi-thread winding section, the air is conditioned by temperature and humidity (temperature 18 - 20 ° C, relative humidity 45-55%). Thus, a low humidity is specially created, which prevents the thread from swelling and contributes to the preservation of the winding shape.
Simultaneously with moistening or immediately after it, a lubricant (preparation) is applied to the thread. This operation is necessary to facilitate the drawing process and to reduce the friction of the thread on the machine parts during drawing and twisting operations. Recently, the combined method of moistening and sizing the yarn during spinning has been increasingly used. In this case, a lubricant is used in the form of an aqueous emulsion containing 5-20% of the preparation substances.
3.3 Molding process parameters
The main parameters of the filament spinning process - temperature and speed are determined by the properties of the polymer, the thickness of the filaments and filaments, the purpose and specified properties of the filaments.
The spinning temperature of the filament usually corresponds to the temperature of the melting grate. The latter varies in the range of 265 - 290 ° C, depending on the molecular weight of the polymer. The larger it is, the higher the spinning temperature of the thread. The jacket temperature is usually 2-5 ° C lower than the grate temperature.
The spinning speed varies in the range of 350 - 1500m / min and depends on the productivity of the melting device, the viscosity of the polymer melt (polymer molecular weight and spinning temperature), and the thickness of filaments and filaments.
Multifilament yarns with a thickness of 29, 93.5 and 187 tex are spun at a speed of 350 to 600 m / min, multifilament yarns with a thickness of 15.6; 6.7; 5; 3.3; 1.67 - at a speed of 700 to 1500 m / min.
3.4 Forming nylon threads
Various types of machines are used in production to form nylon threads of various thicknesses. The quality of the formed yarn in the spinning shop is controlled by the following indicators: the full weight of the bobbins. Linear density of the thread, moisture and lubricant content.
After spinning, nylon yarns do not yet possess a set of properties required for further textile processing, due to their high elongation at break and low strength. To achieve the required properties, they must be subjected to the operations of drawing (3 - 6 times) and twisting.
The properties of the finished filaments (elongation strength, etc.) depend on many factors. The requirements for threads are mainly determined by the area of their application. As a rule, threads intended for the manufacture of textiles should have a higher elongation (26 × 34%) than technical threads (12 × 16%). Therefore, the latter are subjected to stronger stretching. The stretch ability of polyamide yarns makes it possible to obtain them with desired properties and meet the requirements of various consumers. Nylon thread of the same thickness can be obtained with different elongation depending on the purpose.
Under these conditions, the threading of the machine for obtaining complex yarns satisfying all the requirements of the consumer (in terms of thickness, strength, elongation, etc.) is rather difficult. In practice, when refueling the machine, proceed as follows. For a thread of a given thickness, the drawing ratio is set, and the required pump feed and its rotation frequency at a given spinning speed are determined by calculation.
Pump feed Q ( in g / min) is found by the formula
where ? forming speed, m / min, M? the degree of pulling the thread, T? linear density of the thread, tex.
In approximate calculations, corrections that take into account the moisture and lubricant content in the finished yarn, the difference in the content of low-molecular compounds in the freshly formed and finished yarn, as well as shrinkage during finishing and twisting can be disregarded.
Pump speed NS ( rpm) is determined using the following ratio:
where from? the density of the molten polymer q ? pump performance per revolution.
After defining the values Q and NS Experimental spinning of the yarn is carried out at several spinning stations of the machine. The formed thread is stretched with increasing multiplicity until a thread with specified strength and elongation parameters is obtained. If this results in a thread with a deviation in linear density, the linear density of the formed thread is corrected by a corresponding change in the pump flow. After that, the experimental spinning and stretching of the yarn is repeated again until a finished yarn with the desired properties is obtained.
3.5 Textile processing of nylon yarns
Bobbins with unstretched threads coming from the spinning shop are kept in a buffer chamber or in a textile shop under air conditioning conditions (temperature 21-23 ° C, relative humidity 55-65%) for at least 12 hours. This is necessary to average the properties of the thread on the bobbin over the layers of the package and to evenly distribute moisture and lubricant. The nature of the textile processing (degree of drawing and twisting) of nylon threads depends on its thickness and purpose.
Operations for processing nylon threads for textile purposes:
a) hood;
b) twisting with rewinding on perforated bobbins;
c) finishing (removal of low molecular weight compounds and fixation of the twist);
e) air conditioning;
f) rewinding to tapered chucks;
g) sorting.
Nylon yarns, intended for the production of various technical products, are produced from the factory on conical bobbins and are subjected to the same further processing operations. Technical (cord) yarns of 93.5 and 187tex are almost completely processed at the factory into cord fabric. In this case, the complex of textile operations includes the operations of twisting the cord threads and weaving the cord fabric.
Previously, the processing of nylon threads (like other polyamide threads) began with a preliminary twisting operation. Before drawing the thread, depending on the thickness, a twist from 50 to 100 turns / m was reported. Pre-twisting makes the yarn compact, which makes it easier to draw, while reducing the breakage of filaments and filaments and increasing the uniformity of the stretched yarns. In recent years, the preliminary twisting operation has been eliminated at all nylon fiber factories as a result of stricter control of the parameters of all technological processes, the use of raw materials of a higher degree of purity and the use of appropriate sizing compositions on machines. At the same time, production areas have been significantly reduced and labor costs have decreased.
3.5.1 Drawing the threads
This operation is carried out on stretching machines. Of all the operations of the technological process of obtaining nylon threads, the drawing of threads is one of the most critical. This operation largely determines the quality and properties of the threads and, as it were, controls all the previous stages of the process. This is due to the fact that the uniformity of stretching and, consequently, the uniformity of the properties of the stretched thread depend on many factors: the molecular weight of the polymer, the content of low molecular weight compounds, the conditions of formation (temperature and speed), the moisture content of the amount of lubricant applied to the thread, etc.
The properties of threads are characterized not only by the absolute values of physical and mechanical indicators, but to a large extent by the uniformity of these indicators. Fluctuations in the temperature and speed of spinning, humidity and air temperature in the workshop, changes in the conditions of moistening and oiling of the thread and other parameters of the technological process lead to the production of a thread, individual sections of which have unequal properties. Naturally, when pulling such a thread, its individual sections will stretch in different ways, and as a result, the finished thread will have uneven physical and mechanical characteristics. Therefore, strict adherence to the parameters of the technological process is so important.
A schematic diagram of the KV-300-I machine torsion and exhaust mechanism is shown in (Fig. 9). It is used for stretching and twisting of textile yarns with linear density from 1.67 to 15.6 tex for a drawing ratio of 2.42 to 4.90 and a drawing speed of the drawn yarn up to 750 m / min. Output package weight is up to 400g.
Figure 9- Diagram of the mechanism of cold and hot drawing of a technical thread of the KV-300-I machine: 1 - packing with unstretched fiber, 2 - tension guides; 3 - yarn feeder; 4 - power supply device; 5 - brake stick; 6 - upper exhaust disc; 7-heaters; 8 - lower exhaust disc; 9 - thread guide; 10 - kopecks; 11 - a ring with a slider; 12 - spindle.
When stretching polyamide yarns, like many other synthetic yarns made from crystallizable polymers, a characteristic necking effect is observed. A round brake stick is installed between the feeder and the biscuit (in the stretching field) to fix the place of neck formation and increase the uniformity of the thread pulling made of solid material (agate, corundum, etc.), around which the thread makes one turn. As a result of continuous friction of the thread, the stick heats up strongly (up to 80 ° C). Thus, the formation of a neck on the thread (when leaving the stick) is due to the slowing down and heating of it with the stick. A brake stick is used, as a rule, to obtain technical threads; fine threads can be pulled without a stick. This process is called cold drawing.
Nylon yarns for technical purposes with a linear density of 93.5 and 187tex are subjected to combined stretching: cold and hot. In this case, a device for heating the threads to 150 - 180 ° C is placed in the pulling zone.
When spinning the fiber from the melt, the cross-sectional area of the fiber in the region from the outlet from the spinneret to the take-up rollers hyperbolically decreases. A typical variation in the cross-sectional area and radius of a polymer fiber is shown in graph 2. The stretch of fiber is approximately 200 cm long. There is still no way to detect when the fiber starts to solidify.
By the nature of dependencies A (z) and R (z), presented in graph 2, it can be seen that the velocity field in the fiber drawing section is described by functions of the form: . Therefore, to describe the flow, it is necessary to jointly solve the r - and z-components of the equation of motion, the energy balance equation, and the equation of state under the corresponding boundary conditions. This is a rather difficult task, especially when it is necessary to use a non-linear equation of rheological state.
Schedule 2 - Curves of changes in the cross-sectional area and radius of the fiber in the melt drawing section (z - distance from exit from spinnerets). Material, temperature and fiber picking speed respectively 1 - nylon; 265 ° C; 300 m / min; 2 - polypropylene; 262 ° C; 350 m / min.
At present, a mathematical apparatus has not yet been developed that allows one to accurately predict the law of decreasing the fiber radius or the distribution of the flow velocity in the area of intensive decreasing of the fiber radius. True, several attempts have already been made to estimate the speed, fiber radius, and temperature as a function of the distance from the die. The first to investigate non-isothermal fiber spinning were Kees and Matsuo. Hahn's paper generalizes the results obtained by the aforementioned authors and proposes two equations describing the distribution of a single velocity component and
T= T (z) for steady state:
where e is the emissivity, is the mass flow rate, is the heat capacity at constant volume, F D is the force of air resistance (per unit area), equal to
where TO- correction factor; index a indicates that the respective specifications apply to ambient air.
Khan supplemented these two transport equations with a power law of tensile flow, taking into account the temperature dependence of viscosity:
where, is the viscosity at zero shear rate, e is the width, is the activation energy of the viscous flow.
The solution to this system of equations can be obtained only by a numerical method. The results obtained have a physical meaning on the axis section z until the beginning of crystallization, when heat release due to the exothermic effect of crystallization reduces the cooling rate of the melt (graph 3). Here are the results of measuring the temperature of the fiber surface during drawing from the melt, depending on the distance z.
As a result of crystallization of the inner layers, the surface temperature of the fiber may even rise as the distance from the die increases.
Schedule 3 - Tempera dependencefiber surface toursfrom the distance from the diez. Fiber sampling speed: 1 - 50 m / min; 1.93 g / min; 2 - 100 ; 1,93 ; 3 - 200 ; 1,93 ; 4 - 200 ; 0,7 .
Currently, the most attention is attracted to themselves two problems associated with the stability of the process of drawing fibers from the melt, namely: resonance during drawing and fiber formability. In the presence of resonance during drawing, a regular and constant periodicity of change in the diameter of the pulled fiber is observed. Fiber formability refers to the ability of a polymer melt to stretch without rupture due to necking or cohesive failure.
Figure 10 ? Linear fiber crystallizationin fiber spinning. Morphologia structure that developsXia during fiber drawing (1 - spherolistructure; 2 - embryoscrystal, folded lamella; 3 - embryo crystal, straightened lamella). Shaded areaswebs are busy with melt. Speed fromboron fiber: a - very little; b - small; v - average; G - high.
Similar documents
Classification of chemical fibers. The properties and qualities of their artificial varieties: viscose and acetate fiber. Polyamide and polyester analogs. Scope of application of nylon, lavsan, polyester and polyacrylonitrile fibers, acrylic yarn.
presentation added 09/14/2014
Stages of production of chemical fibers. Graphite and non-graphitized carbon types. High-strength, heat-resistant and non-combustible fibers and threads (phenylone, vnivlon, oxalon, armide, carbon and graphic): composition, structure, production, properties and application.
test, added 07/06/2015
Comparative characteristics of the chemical and physicochemical properties of heterochain and carbon chain fibers. Dyeing technology for cotton, linen and a mixture of cellulose and polyester fibers. The essence of the final finishing of woolen fabrics.
test, added 09/20/2010
Types of artificial fibers, their properties and practical application. Viscose, copper-ammonia and acetate fibers, cellulose as a starting material for their production. Improving the consumer properties of yarn through the use of chemical fibers.
term paper, added 12/02/2011
Analysis of the development of the production of chemical fibers. The main directions of improving the methods of obtaining viscose fibers. Modern technologies for obtaining hydrated cellulose fibers. Description of the technological process. Environmental expertise of the project.
thesis, added 08/16/2009
Physical and mechanical properties of basalt fibers. Production of aramid fibers, threads, ropes. The main area of application of fiberglass and glass fiber materials. Purpose, classification, scope of carbon fiber and carbon fiber reinforced plastic.
test, added 10/07/2015
Directions of rational use of electricity. Material and energy balances of technological processes. Thermal processing of fuels. Classification of chemical fibers. Characteristics of equipment, machine tool.
manual, added 01/15/2010
Nomenclature of quality indicators of yarns and threads for the textile industry. Properties of yarns made from natural, vegetable and chemical fibers. Consumer properties of knitted fabric, the advantages of its use in the manufacture of garments.
term paper, added 12/10/2011
Comparison of the physical and chemical properties of natural silk and lavsan fibers. Fiber structure, its effect on appearance and properties. Comparison of flax linen wet spinning system and combed dry spinning system. Hygienic properties of fabrics.
test, added 12/01/2010
Chemical devices for conducting one or several chemical, physical or physicochemical processes in them. Apparatus with stirring devices, their use in the chemical industry. Determination of the structural dimensions of the apparatus.
