The structure and properties of natural fibers. The concept of textile fibers Message natural fibers of plant origin

fibers plant origin. Vegetable fibers include cotton and bast.

Cotton is the fibers that cover the seeds of the cotton plant. The main substance (94-96%) that makes up cotton fiber is cellulose. Associated substances (4-6%) include water, pectin (gluing), fat and wax, ash substances, etc.

Cotton fiber of normal maturity under a microscope looks like a flat ribbon with a corkscrew crimp and a channel filled with air inside.

Cotton fiber has many positive properties. First of all, it has a high hygroscopicity (8~12%), so cotton fabrics and cotton products have good hygienic properties.

Cotton has the ability to quickly absorb moisture and quickly evaporate it, that is, it dries quickly. When immersed in water, the fibers swell, and their strength increases by 10-20%. Cotton is resistant to alkalis, but is destroyed even by dilute acids.

The ability of cotton to swell in alkalis and at the same time increase strength, dyeability and acquire silkiness and luster is based on a special finishing operation - mercerization. The fibers are quite strong. Cotton has a relatively high heat resistance - the destruction of the fiber at temperatures up to 130 ° C does not occur. Cotton fiber is more resistant than viscose and natural silk to the action of light, but in terms of light resistance it is inferior to bast and wool fibers. Cotton fibers burn with a yellow flame, forming gray ash, and there is a smell of burnt paper. The negative properties of cotton fiber are high wrinkling (due to low elasticity), high shrinkage, and low resistance to acids.

Linen. Fibers that are obtained from the stems, leaves or shells of the fruits of plants are called bast. Strong coarse fibers are produced from hemp stalks - hemp, which is used for container fabrics and rope and rope products. Coarse technical fibers (jute, kenaf, ramie) are obtained from the stems of plants of the same name. Of all the bast fibers, flax has received the greatest use.

Flax fibers are obtained from the bast part of the stem. Flax is an annual herbaceous plant.

A characteristic feature of bast fibers, unlike others, is that they are bundles of fibers connected by pectin substances. During prolonged boiling soapy soda solutions pectin substances are washed out and flax is divided into individual fibers.

A single flax fiber is one plant cell. Under the microscope, the fiber in longitudinal form is a cylinder with thick walls. The cross section of the fiber is a polygon with 5-6 faces.

The surface of the fiber is more even and smooth, as a result of which linen fabrics are less soiled than cotton fabrics and are easier to wash. These properties of flax are especially valuable for linens.

The fiber contains 80% cellulose and 20% impurities - waxy, fatty, coloring, mineral and lignin (5%). Lignin is a product of lignification of the cell, which gives flax increased rigidity. The content of lignin in flax fiber makes it resistant to light, weather, microorganisms.

The strength of elementary fibers is 3-5 times higher than the strength of cotton, and the extensibility is the same times less, so linen cushioning fabrics better retain the shape of products than cotton ones. The fibers shine because they have a smooth surface. The physical and chemical properties of flax and cotton are close enough. Linen fiber is unique in that, with high hygroscopicity (12%), it absorbs and releases moisture faster than other textile fibers. A feature of flax is its high thermal conductivity, so the fibers are always cool to the touch. Thermal destruction of the fiber does not occur up to a temperature of 160 °C. The chemical properties of flax fiber are similar to cotton fiber, i.e. it is resistant to alkalis, but not resistant to acids. Due to the fact that linen fabrics have their own beautiful silky sheen, they are not subjected to mercerization. A negative property of flax fiber is its strong crease due to low elasticity. Flax fibers are bleached and dyed, as they have a more intense natural color, thick walls.

fibers of animal origin. Animal fibers include wool and natural silk.

Wool is the fibers of the removed hairline of sheep, goats, camels, rabbits and other animals. Wool is obtained mainly from sheep (97-98%), in smaller quantities from goats (up to 2%), camels (up to 1%). Wool fibers are made up of the protein keratin.

Wool fibers under a microscope can be easily distinguished from other fibers - their outer surface is covered with scales. Under the microscope, a peculiar crimp of wool fibers is visible. Their curls are wavy, in contrast to cotton fibers, whose curls are corkscrew. Fine wool has a strong crimp.

Wool can be of the following types: down, transitional hair, awn and dead hair. Down is a thin, highly crimped, silky fiber; transitional hair is uneven in thickness, strength, has less crimp; awn and dead hair are characterized by greater thickness, lack of tortuosity, increased rigidity and brittleness, low strength, dead hair is poorly dyed, breaks easily and falls out of finished products.

Wool can be homogeneous (from fibers of predominantly one type, for example, fluff) and heterogeneous (from fibers different types- fluff, transitional hair, etc.). Depending on the thickness of the fibers and the uniformity of their composition, wool is divided into fine, semi-fine, semi-coarse and coarse. Fine wool consists of fine fibers of down, semi-fine consists of thicker down or transitional hair; semi-coarse can be homogeneous and heterogeneous and consist of fluff, transitional hair and a small amount of awn; coarse - heterogeneous and includes all types of fibers, including awn and dead hair.

Woolen fiber has high elasticity, and consequently, low wrinkling. Wool is a strong enough fiber, elongation at break is high. When wet, the fibers lose 30% of their strength.

The luster of the coat is determined by the shape and size of the scales covering it: large flat scales give the coat maximum luster; small, strongly lagging scales make it matte.

The properties of wool are unique - it has a high felting ability, which is explained by the presence of a scaly layer on the surface of the fiber. This property is taken into account when finishing (rolling) cloth fabrics, felt, felt, blankets, in the production of felted shoes.

Wool has a low thermal conductivity, so the fabrics have high heat-shielding properties.

In terms of hygroscopicity, wool surpasses all fibers. It slowly absorbs and evaporates moisture and therefore does not cool down, remaining dry to the touch. A number of operations are based on the ability of wool to change its extensibility and shrinkage during wet-heat treatment: suture, pulling and decathing. When dry, wool shrinks to the maximum, so products made from it are recommended to be dry-cleaned.

Wool fiber is more resistant to light than cotton and linen. But with prolonged exposure, it is destroyed.

Alkalis have a destructive effect on wool, it is resistant to acids. Therefore, if wool fibers containing vegetable impurities are treated with an acid solution, then these impurities, consisting of cellulose, will dissolve, and the wool fibers will remain pure. This process of cleaning wool is called carbonization.

In the flame, the wool fibers are sintered, but when taken out of the flame they do not burn, forming a sintered black ball at the end of the fibers, which is easily rubbed, and the smell of a burnt feather is felt. The disadvantage of wool is low heat resistance - at a temperature of 100-110 C, the fibers become brittle and stiff, their strength decreases.

Natural silk in terms of its properties and cost is the most valuable textile raw material. It is obtained by unwinding cocoons formed by silkworm caterpillars. Silk has the greatest distribution and value. silkworm, which accounts for 90% of the world's silk production.

When examining a cocoon thread under a microscope, two silk fibers are clearly visible, unevenly glued together with sericin. There are two proteins in the composition of the cocoon thread: fibroin (75%), which makes up silk, and sericin (25%).

Of all natural fibers, natural silk is the lightest fiber and, along with a beautiful appearance, has high hygroscopicity (11%), softness, silkiness, low wrinkling, is an indispensable raw material for the manufacture of summer clothes (dresses, blouses).

Natural silk is highly durable. The breaking load of silk when wet is reduced by about 15%.

The chemical properties of natural silk are similar to wool, that is, it is resistant to acids, but not to alkali.

Natural silk has the lowest light fastness, so at home products are not dried in the light, especially when sunshine. Other disadvantages of natural silk include low heat resistance (same as wool) and high shrinkage, especially for twisted threads.

Chemical fibers. Chemical fibers are obtained by chemical processing of natural (cellulose, proteins, etc.) or synthetic macromolecular substances (polyamides, polyesters, etc.).

The main raw materials for the production of chemical fibers are wood, cotton waste, glass, metals, oil, gases and coal.

Fibers are formed from melts or solutions of macromolecular compounds. The melt or spinning solution of a macromolecular substance (polymer) is filtered and forced through the finest holes in the spinnerets. Spinnerets are the working bodies of spinning machines that carry out the process of spinning fibers. Jets of spinning solutions or melts flowing out of the spinneret solidify to form filaments. Using spinnerets with holes of complex configuration, it is possible to obtain profiled and hollow fibers.

1. Artificial fibers. Artificial fibers include fibers obtained by processing natural high-molecular compounds - cellulose, proteins. More than 99% of these fibers are made from cellulose.

Viscose fiber is one of the first chemical fibers produced on an industrial scale. For its manufacture, usually wood, mainly spruce, cellulose is used, which, by processing with chemical reagents, is converted into a spinning solution - viscose.

Viscose fibers are highly hygroscopic (11 - 12%), so products made from them absorb moisture well and are hygienic; in water, the fibers swell strongly, while the cross-sectional area increases by 2 times. They are sufficiently resistant to abrasion, so it is advisable to use them for the production of products for which high wear resistance and hygienic properties are important characteristics (for example, for lining and shirt fabrics).

Viscose fiber has high heat resistance, medium strength and elongation, in relation to acids and alkalis - similar to cotton and linen.

However, viscose fiber has a number of significant drawbacks, which are manifested in products made from it - this is a strong crease due to low elasticity and high shrinkage (6-8%). Another disadvantage of viscose fiber is big loss wet strength (50-60%). To reduce the disadvantages, viscose fiber is physically or chemically modified, obtaining polynose fibers, mtilon, siblon, etc. Polynose fiber resembles fine-staple cotton and is used in the production of shirts, underwear, and other fabrics. Mtilon is a wool-like viscose fiber that is used for pile carpets. Siblon is a substitute for medium fiber cotton.

Acetate fibers are obtained from cotton fluff or refined wood pulp.

When cellulose is exposed to acetic anhydride, acetic and sulfuric acids, acetyl cellulose is formed, from the solution of which acetate fibers or threads are obtained. Depending on the solvents and other chemicals used, diacetate, called acetate, and triacetate fibers are obtained.

Some of the properties of acetate and triacetate fibers are common, and some have their own characteristics. So, to the general positive properties include low wrinkling and shrinkage (up to 1.5%), as well as the ability to maintain the effects of corrugation, pleats in products even after wet treatments; to the disadvantages that hinder their use in the range of products - low resistance to abrasion, as a result of which it is not advisable to use them in the range of lining, shirt, suit fabrics. It is better to use these fibers in an assortment of tie fabrics, for which wear resistance is not of great importance. Other common disadvantages of fibers include high electrification and the tendency of products to form creases when wet.

The differences in the properties of acetate and triacetate fibers are as follows. The hygroscopicity of acetate fibers is higher (6.2%) than that of triacetate fibers (4.5%), however, the latter are better dyed and have greater light and heat resistance (180 X versus 140-150 * C).

Of the other artificial fibers in the production of fabrics, alunit (Lurex), plasticex, and metanit are used.

2. Synthetic fibers. Synthetic fibers are obtained from natural low molecular weight substances (monomers), which are converted into high molecular weight substances (polymers) by chemical synthesis.

Synthetic fibers, in comparison with artificial ones, have high wear resistance, low creasing and shrinkage, but their hygienic properties are low.

Polyamide fibers (nylon). Capron fiber, which is used most widely, is obtained from coal processing products.

The positive properties of kapron fibers include high strength, as well as the greatest resistance to abrasion along bends of textile fibers. These valuable properties of nylon fiber are used when it is mixed with other fibers to obtain wear-resistant materials, the introduction of 5-10% nylon fiber into a woolen fabric increases its abrasion resistance by 1.5-2 times. Nylon fiber also has low creasing and shrinkage, resistance to the action of microorganisms.

When introduced into the flame, capron melts, ignites with difficulty, burns with a bluish flame. If the molten mass begins to drip, the combustion stops, a melted brown ball forms at the end, and the smell of sealing wax is felt.

However, nylon fiber is slightly hygroscopic (3.5-4%), so the hygienic properties of products made from such fibers are low. In addition, nylon fiber is rigid, highly electrified, unstable to the action of light, alkalis, mineral acids, and has low heat resistance. On the surface of products made from nylon fibers, pills are formed, which, due to the high strength of the fibers, remain in the product and do not disappear during wear.

Polyester fibers, PET polyethylene terephalate (lavsan or polyester). The feedstock for the production of lavsan are oil refining products.

In the global production of synthetic fibers, these fibers come out on top. Lavsan fiber is characterized by excellent crease resistance, superior to all textile fibers, including wool. So products made of lavsan fibers are 2-3 times less wrinkled than woolen ones. In order for products with cellulose fibers to become low-crease, 45-55% of lavsan fibers are added to the mixture to these fibers.

Lavsan fiber has very good light and weather resistance (second only to nitron fiber). For this reason, it is advisable to use it in curtain-tulle, awning, tent products. Lavsan fiber is one of the heat-resistant fibers. It is thermoplastic due to which the products retain the effects of pleated and corrugated well. In terms of resistance to abrasion and bending, lavsan fiber is somewhat inferior to kapron. But the tensile strength and elongation at break are high. The fiber is resistant to dilute acids, alkalis, but is destroyed when exposed to concentrated sulfuric acid and hot alkali. Lavsan burns with a yellow smoky flame, forming a black non-rubbing ball at the end.

However, lavsan fiber has low hygroscopicity (up to 1%), poor dyeability, increased rigidity, electrified and pilling properties. Moreover, the pills remain on the surface of the products for a long time.

Polyacrylonitrile (PAN) fibers (acrylic or nitron). The raw materials for the manufacture of nitron are the products of coal, oil, and gas processing.

Nitron is the softest, silkiest and warmest synthetic fiber. In terms of heat-shielding properties, it surpasses wool, but in terms of abrasion resistance it is inferior even to cotton. The strength of nitron is half that of nylon, the hygroscopicity is low (1.5%). Nitron is acid-resistant, resistant to all organic solvents, but is destroyed by alkalis.

It has low shrinkage and shrinkage. Outperforms all textile fibers in light fastness. Nitron burns with a yellow smoky flame with flashes, forming a solid ball at the end.

The fiber is brittle, poorly dyed, highly electrified and pilled, but pills disappear during wear due to low strength properties.

Polyvinyl chloride fibers are produced from polyvinyl chloride - PVC fiber and from perchlorovinyl - chlorine. The fibers are distinguished by high chemical resistance, low thermal conductivity, very low hygroscopicity (0.1-0.15%), the ability to accumulate electrostatic charges when rubbed against human skin, which have a therapeutic effect in diseases of the joints. The disadvantages are low heat resistance and instability to the action of light.

Polyvinyl alcohol fibers (vinol) are obtained from polyvinyl acetate. Vinol has the highest hygroscopicity (5%), is highly resistant to abrasion, yielding only to polyamide fibers, and is well dyed.

Polyolefin fibers are obtained from melts of polyethylene and polypropylene. These are the lightest textile fibers, products made from them do not sink in water. They are resistant to abrasion, chemical reagents, and have high tensile strength. The disadvantages are low light resistance and low heat resistance.

Polyurethane fibers (spandex and lycra) are elastomers, as they have exceptionally high elasticity (extensibility up to 800%). They are light, soft, resistant to light, washing, sweat. The disadvantages include: low hygroscopicity (1 - 1.5%), low strength, low heat resistance.

natural fiber nature itself creates.

From ancient times until the end of the 19th century, the only raw materials for the production of textile materials were natural fibers, which were obtained from various plants. At first it was the fibers of wild plants, and then the fibers of flax and hemp. With the development of agriculture, cotton began to be cultivated, which gives very good and durable fiber.

Fibers produced from plant stems are widely used, they are called bast. The fibers from the stems are mostly coarse, strong and tough - these are the fibers of kenaf, jute, hemp and other plants. Finer fibers are obtained from flax, from which fabrics for the manufacture of clothing and linen are produced.

Kenaf cultivated mainly in India, China, Iran, Uzbekistan and other countries. Kenaf fiber is highly hygroscopic and durable. Burlap, tarpaulin, twine, etc. are made from it.

Hemp- very ancient culture, is grown to obtain fiber mainly in our country, India, China, etc. It grows in the wild in Russia, Mongolia, India, China. Fiber (hemp) is obtained from hemp stalks, from which marine ropes, ropes, and canvas are made.

Jute cultivated in tropical regions of Asia, Africa, America and Australia. Jute is grown in small areas in Central Asia. Jute fibers are used for the manufacture of technical, packaging, furniture fabrics and carpets.

Of the fibers of plant origin, the most famous cotton and linen.

Cotton is a very ancient crop. It began to be cultivated in India over 4000 years ago. Remains of cotton fabrics were found in the graves of ancient Peruvians excavated in the deserts of Peru and Mexico. This means that even earlier than in India, the Peruvians knew cotton and knew how to make fabrics from it.

Cotton called the fibers that cover the surface of the seeds of an annual cotton plant that grows in warm southern countries. The development of cotton fibers begins after the flowering of cotton during the formation of fruits (bolls). The length of cotton fibers ranges from 5 to 50 mm. Cotton collected and pressed into bales is called raw cotton.

During the primary processing of cotton, the fibers are separated from the seeds and cleaned of various impurities. First, the longest fibers (20-50 mm) are separated, then short or fluff (6-20 mm) and finally the down (less than 6 mm). The long fibers are used to make yarn, the down is used to make wadding and, when mixed with long cotton fibers, to make thick yarns. Fibers less than 12 mm long are chemically processed into cellulose to produce man-made fibres.

Wheat and flax are the most ancient cultivated plants. Flax began to be cultivated nine thousand years ago. AT mountainous areas In India, for the first time, they began to make fabrics from it, beautiful and thin.

Seven thousand years ago, flax was already known in Assyria, Babylonia. From there he entered Egypt.

Linen fabrics have become a luxury item there, replacing the previously common woolen ones. Only Egyptian pharaohs, priests and nobles could afford clothes made from linen fabrics.

Later, the Phoenicians, and then the Greeks and Romans, began to make sails for their ships from linen.

Our ancestors, the Slavs, loved snow-white heavy linen fabrics. They knew how to cultivate flax, allocating the best land for crops. Among the Slavs, linen fabrics served as clothing for the common people.

Linen fibers make a heavy, durable white fabric. It is great for tablecloths, wearables and bed linen.

And flax, sown thickly and removed from the field during flowering, gives a very delicate fiber, which goes to thin and light cambric.

Linen is an annual herbaceous plant that will give the fiber of the same name. Flax fiber is located in the stem of the plant and can reach 1 meter. Flax is harvested during the period of early yellow ripeness. The resulting raw material for the production of yarn (threads) is subjected to further processing.

The primary processing of flax consists of soaking the flax straw, drying the straw, washing and scutching to separate the impurities.

Yarn is obtained from cleaned and sorted fibers.

Positive properties of cotton fabrics: good hygienic and heat-shielding properties, strength, light fastness. Under the action of water, cotton fibers even swell and increase strength, that is, they are not afraid of any washing. The fabrics are good appearance, it is easy to look after products from them.

Due to the fact that cotton fabrics have good hygroscopicity and high air permeability, and linen fabrics have higher hygroscopicity and medium air permeability, they are used for the manufacture of bed linen and household clothing.

Disadvantages of cotton fabrics: strong wrinkling (fabrics lose their beautiful appearance when worn), low abrasion resistance, therefore low wear.

Disadvantages of linen fabrics: Strong wrinkling, low drape, stiffness, high shrinkage.

Natural fibers of animal origin

natural fibers animal origin- woolen and silk. Fabrics made from such fibers are environmentally friendly and therefore represent a certain value for a person and have a positive effect on his health.

Since time immemorial, people have used wool to make fabrics. Since the very time they began to engage in cattle breeding. The wool of sheep and goats was used, and in South America and lam.

During the Mongol-Tibetan expedition of 1923-1926, the well-known Russian geographer-researcher P.K. Kozlov unearthed mound burials, in which he discovered ancient woolen fabrics. Even after lying underground for several thousand years, some of them surpassed modern threads in terms of strength.

The bulk of the wool is obtained from sheep, with fine-fleeced merino sheep producing the best wool. Fine-fleeced sheep have been known since the 2nd century BC, when the Romans crossed Colchian rams with Italian sheep and bred the Tarentine breed of sheep with brown or black wool. In the 1st century, by crossing the Tarentine sheep with African rams in Spain, the first merinos were obtained. From this first herd, all other Merino breeds eventually descended: French, Saxon, etc.

Sheep are sheared once or in some cases twice a year. From one sheep they get from 2 to 10 kilograms of wool. From 100 kilograms of raw wool, 40-60 kilograms of pure wool are obtained, which is sent for further processing.

From the wool of other animals, goat mohair wool is widely used, obtained from Angora goats, originating from the Turkish town of Angora.

For the manufacture of outerwear and blankets, camel hair is used, obtained by shearing or combing during camel molting.

High resilient cushioning materials are obtained from horsehair.

To the inexperienced eye, almost all wool looks the same. But a highly qualified specialist is able to distinguish over seven thousand varieties!

In the XIV-XV centuries, wool intended for spinning was combed with a wooden comb, which had several rows of steel teeth. As a result, the fibers in the bundle were arranged in parallel, which is very important for their uniform stretching and twisting during spinning.

From the combed fiber, strong, beautiful threads were obtained, from which a good-quality fabric was produced that did not wear out for a long time.

Wool- this is the hairline of animals: sheep, goats, camels. The main mass of wool (95-97%) is given by sheep. The wool cover is removed from the sheep with special scissors or machines. The length of wool fibers is from 20 to 450 mm. They cut off an almost whole inseparable mass, which is called a rune.

Types of wool fibers- this is hair and wool, they are long and straight, and fluff - it is softer and more crimped.

Before being sent to textile factories, wool is subjected to primary processing: sorted, that is, fibers are selected according to quality; shake - loosen and remove clogging impurities; washed with hot water, soap and soda; dried in dryers. Then yarn is made, and fabrics are made from it.

In the finishing industry, fabrics are dyed in various colors or apply various patterns to fabrics. Wool fabrics are produced in plain dyed, multicolored and printed.

Wool fibers have the following properties: have high hygroscopicity, that is, they absorb moisture well, elastic (products wrinkle a little), resistant to sun exposure (higher than that of cotton and linen).

To check the wool fiber, you need to set fire to a piece of fabric. During combustion, the wool fiber is sintered, the resulting sintered ball is easily rubbed with fingers. In the process of burning, the smell of burnt feather is felt. In this way, you can determine the fabric: it is pure wool or artificial.

Woolen fibers are used to make dresses, suits and coats. Woolen fabrics go on sale under the following names: drape, cloth, tights, gabardine, cashmere, etc.

There are several species of butterflies whose caterpillars weave cocoons before turning into pupae, using secretions from special glands. These butterflies are called silkworms. The silkworm is mainly bred.

Silkworms develop in several stages: egg (grain), caterpillar (larva), chrysalis and butterfly. The caterpillar develops in 25-30 days and goes through five instars separated by molts. Its length by the end of development reaches 8, and the thickness is 1 centimeter. At the end of the fifth instar, the silk glands of caterpillars are filled with silk mass. Silk - a thin paired thread of the protein substance of fibroin - is squeezed out in a liquid state, and then hardens in air.

The formation of a cocoon lasts 3 days, after which the fifth molt occurs, and the caterpillar turns into a chrysalis, and after 2-3 weeks into a butterfly that lives 10-15 days. The female butterfly lays grena, and a new cycle of development begins.

From one box of grena weighing 29 grams, up to 30 thousand caterpillars are obtained, eating about a ton of foliage and giving four kilograms of natural silk.

To get silk natural course silkworm development is interrupted. At harvesting stations, the collected cocoons are dried, then treated with hot air or steam to prevent the process of turning pupae into butterflies.

At silk factories, cocoons are unwound by joining together several cocoon threads.

Natural silk- These are thin threads that are obtained by unwinding the cocoons of the silkworm caterpillar. A cocoon is a dense, tiny egg-like shell that the caterpillar twists tightly around itself before turning into a chrysalis. Four stages of silkworm development - egg, caterpillar, chrysalis, butterfly.

Collect cocoons in 8-9 days from the beginning of curling and send for primary processing. The purpose of the primary processing is to unwind the cocoon thread and connect the threads of several cocoons. The length of the cocoon thread is from 600 to 900 m. Such a thread is called raw silk. The primary processing of silk includes the following operations: treatment of cocoons with hot steam to soften the silk glue; winding threads from several cocoons at the same time. In textile factories, raw silk is used to produce fabric. Silk fabrics are produced by plain-dyed, multi-colored, printed.

Silk fibers have the following properties: they have good hygroscopicity and air permeability, less resistant to sunlight than other natural fibers. Silk burns just like wool. Products made of natural silk are very pleasant to wear due to their good hygienic properties.

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Fibers are the main starting material for the production of textile products. They can be divided into several groups. Natural fibers or natural fibers are divided into textile fibers of vegetable (for example, cotton, linen, hemp), animal (wool, natural silk) and mineral (asbestos) origin, suitable for making yarn. Chemical fibers are obtained from the products of chemical processing of natural polymers (artificial fibers) or from synthetic polymers (synthetic fibers). Manufacture of man-made fibers usually consists of forcing a solution or melt of a polymer through the orifices of a spinneret into a medium that causes the resulting fine fibers to solidify. Cold air serves as such a medium for molding from melts, hot air from solutions (“dry” method) or a special solution - a precipitation bath (“wet” method). They are produced in the form of monofilament, staple fiber or a bundle of many thin threads connected by twisting.

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Natural fibers of plant origin can be divided into two groups: cotton or cotton and bast fibers. Cotton is commonly referred to as the fibers that cover the seeds of the cotton plant. Bast fibers are called fibers contained in the stems, leaves and shells of the fruits of various plants. The following types of bast fibers are most common: flax, hemp (hemp fiber), jute, etc.

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COTTON - fibers that cover cotton seeds. When it ripens, the fruits (boxes) open, and raw cotton (fiber with unseparated seeds) is harvested from them. The box contains seeds covered with cellulose fibers, which can be long or short. Therefore, cotton is called long-staple or short-staple. The quality of materials produced from cotton depends on this. During processing, cotton fiber (fibers longer than 20 mm), fluff (less than 20 mm) and downs (less than 5 mm) are separated from the seeds. Cotton is used to produce fabrics, knitwear, threads, cotton wool, etc. Cotton down and downs are used in the chemical industry as a raw material for the manufacture of artificial fibers and threads, films, varnishes, etc. Cotton is resistant to alkalis, but decomposes under the action of acids .

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WOOL are fibers obtained by shearing sheep, goats, camels and other animals. The quality of wool depends on the thickness of the cross section and the length of the wool fibers. The bulk of the wool processed in the industry is sheep. Types of wool fibers: down - the most valuable thin, soft crimped fiber; transitional hair, that is, thicker, stiffer and less crimped than down; "dead hair" low-strength and hard fiber. Wool is used to produce yarn, fabrics, knitwear, felt products, etc. Wool is sensitive to the action of alkalis, which make it brittle, and in relation to acids, on the contrary, it is stable. By chemical composition wool is a protein substance. When wool is burned, the characteristic smell of burnt feathers is released.

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Flax is a genus of annual and perennial herbs and shrubs of the flax family, a spinning and oilseed crop. Cultivated mainly fiber flax in stems 20-28% fiber, and oil flax, or curly flax, in seeds 35-52% linseed oil. Flax fibers are obtained from the bast stem of flax. This is the first fiber that a person learned to receive already in the Stone Age. Long flax fibers are made up of cellulose. Linen is the strongest natural fiber. Therefore, it is used in the production of strong threads, fabrics for sails, and due to good hygienic properties linen fabrics are used to make linen.

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SILK - natural textile thread of animal origin; a product secreted by the glands of silkworm caterpillars. With the joint unwinding of several cocoons, raw silk is obtained, from which twisted silk is produced, used for the manufacture of fabrics, knitwear, and sewing threads. Waste is processed into yarn for technical and other fabrics. According to the chemical composition, silk is a protein substance. Soft, shiny, beautiful-looking products made of silk, however, have low wear resistance and high cost.

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Chemical fibers are obtained from the products of chemical processing of natural polymers (artificial fibers) or from synthetic polymers (synthetic fibers). Polymers (from poly... and Greek meros share, part), substances whose molecules (macromolecules) consist of a large number of repeating units; the molecular weight of polymers can vary from a few thousand to many millions. By origin, polymers are divided into natural, or biopolymers (for example, proteins, nucleic acids, natural rubber), and synthetic (for example, polyethylene, polyamides, epoxy resins), obtained by polymerization and polycondensation methods. According to the shape of the molecules, linear, branched and network polymers are distinguished, organic, element-organic, inorganic polymers by nature. Linear and branched polymers are characterized by a set of specific properties, for example, the ability to form anisotropic fibers and films, as well as to exist in a highly elastic state. Polymers are the basis of plastics, chemical fibers, rubber, paintwork materials, adhesives, ion exchangers. The cells of all living organisms are built from biopolymers.

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Over the years, natural fibers have ceased to fully satisfy a person, so scientists around the world have been working to find a replacement for them. More than three hundred years ago (in 1655), the outstanding English physicist Robert Hooke published a treatise in which there was such a statement: “It is possible, apparently, to find ways to artificially obtain a sticky mass, similar to how it is formed in a silkworm ... If such a mass is found, then, apparently, an easier task will be to find a way to stretch this mass into thin threads ... ”But only in 1884, the student of Louis Pasteur, the French inventor Hilaire de Chardonnay, managed to obtain artificial fibers. The most common types of artificial fibers are obtained by processing cellulose. Chardonnay was the first to decide to use a solvent to dissolve cellulose into a solution and from this solution to obtain a new fiber. To do this, he forced the resulting liquid mass through thin holes. To obtain fibers, a polymer solution or melt is forced through the finest holes in a spinning die. From the obtained fibers, threads are spun, which are used for the manufacture of textile products.

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When processing waste wood and sawdust, cellulose is released. In the process of obtaining viscose fiber, cellulose is treated with reagents (NaOH and CS2). Viscose fiber - an artificial fiber molded from viscose; consists of hydrated cellulose. Easily colored, hygroscopic; Disadvantages: large loss of strength in the wet state, easy wrinkling, low wear resistance are eliminated by modifying the viscose fiber. Due to the availability of raw materials and the low cost of reagents, the production of viscose fiber is highly economical. It is used (sometimes mixed with other fibers) for the production of clothing fabrics, knitwear, cord. In the process of obtaining acetate fibers, cellulose is treated with acetic anhydride, the resulting cellulose acetate is dissolved in acetone and forced through spinnerets.

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Acetate fibers are artificial fibers formed from solutions of cellulose triacetate (triacetate fiber) and its partial saponification product (acetate fibers proper). Soft, elastic, little wrinkled, let in ultraviolet rays; disadvantages: low strength, low thermal and wear resistance, significant electrification. They are mainly used in the production of consumer goods, such as underwear. World production is about 610 thousand tons.

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Polyamide fiber is a synthetic fiber formed from melts or solutions of polyamides. Strong, elastic, resistant to abrasion, repeated bending and the action of many chemicals; disadvantages: low hygroscopicity, increased electrification, low thermal and light resistance. It is used in the production of fabrics, knitwear, tire cord, filter materials, etc. The main trade names: from polycaproamide capron, nylon-6, perlon, dederon, amylan, stilon; from polyhexamethylene adipamide anide, nylon-6,6, rhodianylon, niplon.

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Polyester fiber is a synthetic fiber formed from a melt of polyethylene terephthalate or its derivatives. Advantages insignificant creasing, excellent light and weather resistance, high strength, good resistance to abrasion and organic solvents; Disadvantages: Difficulty in dyeing, strong electrification, rigidity is eliminated by chemical modification. It is used, for example, in the production of various fabrics, artificial fur, ropes, for reinforcing tires. Main trade names: lavsan, terylene, dacron, teteron, elana, tergal, tesil.

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Polyacrylonitrile fiber (acrylic fiber) is a synthetic fiber formed from solutions of polyacrylonitrile or its derivatives. In many properties it is close to wool, resistant to light and other atmospheric agents, acids, weak alkalis, organic solvents. Polyacrylonitrile fiber is used to make upper and underwear knitwear, carpets, and fabrics. Main trade names: nitron, orlon, acrylan, kashmilon, kurtel, dralon, volprula.

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The structure and properties of natural fibers.

1.Vegetable fibers.

The main polymer that makes up natural fibers of plant origin is cellulose belonging to the class of polysaccharides.

A characteristic feature of cellulose is the presence of three hydroxyl groups in each elementary unit; this feature determines the basic physical and mathematical properties of cellulose fibers.

From existing species The most common cellulose fibers are cotton and linen fibers.

Cotton fibre. Cotton is the name given to the fibers that cover the surface of the seeds of the annual cotton plant, which grows in warm climates. southern regions countries (in Central Asia, Transcaucasia, Kazakhstan). The development of cotton fibers begins after the flowering of cotton during the formation of fruits (bolls). At this time, on the surface of the seeds, individual cells of the shell begin to grow intensively in length, forming thin-walled tubes with protoplasm, consisting of simple carbohydrate compounds (Fig. 1.3). During the ripening period, when the cotton bolls open, the growth of fibers in length stops and, as a result of the process of photosynthesis, a-cellulose is released from the protoplasm.

Based on cotton, satin, batiste, gauze, chintz, denim, flannel, canine, teak, calico, voile, percale, nansuk, organdy, pique, poplin, veil and other fabrics are produced.

The advantages of cotton fabric: strength, high wear resistance, alkali resistance and elasticity. The fabric is warm, soft and pleasant to the touch, absorbs moisture well, does not electrify.

Disadvantages: high creasing.

Linen fibre. To obtain this fiber, a special type of flax is grown - fiber flax, which is an annual herbaceous plant with a straight non-branching stem.

The main substance of which the fibers are composed is cellulose (about 75%). Associated substances include: lignin, pectin, fat and wax, nitrogenous, coloring, ash substances, water.

Linen fiber has four to six faces with pointed ends and characteristic strokes (shifts) in separate areas, resulting from mechanical effects on the fiber during its production.

Unlike cotton, flax fiber has relatively thick walls, a narrow channel closed at both ends; the surface of the fiber is more even and smooth, in connection with this, linen fabrics are less polluted than cotton ones and are easier to wash.

These properties of flax are especially valuable for linens. Linen fiber uniquely absorbs and releases moisture faster than other textile fibers; it is stronger than cotton. The content of lignin in flax fiber makes it resistant to light, weather and microorganisms. The chemical properties of flax fiber are similar to cotton fiber, i.e. it is resistant to alkalis, but not resistant to acids. Linen fiber is heavily wrinkled due to low elasticity, it is difficult to bleach and dye.

Due to the high hygienic and strength properties, linen fabrics (for underwear, table, bed linen), summer costume and dress fabrics are obtained from flax fibers. Canvas, fire hoses, cords, shoe threads are also made from flax fibers, and coarser fabrics are made from flax tow: bag, canvas, tarpaulins, canvas, etc.

2. Animal fibers.

The main substances that make up natural fibers of animal origin (wool and silk) are proteins - keratin and fibroin. The difference in the molecular structure of these proteins determines the differences in the properties of wool and silk fibers. This may explain the higher strength of silk and its lower ability to deform when stretched.

Compared to cellulose, proteins are more resistant to weakly concentrated acids. Proteins are not resistant to the action of alkalis, which explains the low mechanical properties of wool and silk.

The light fastness of silk is higher than that of cellulose fibers, while wool is lower.

Wool. Wool is usually called the hair fiber of various animals: sheep, goats, camels, etc.
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The industry mainly processes natural sheep wool (fleece).

The main substance of wool fiber is keratin, which belongs to protein compounds.

The fiber has three layers: scaly, cortical and core.

The scaly layer is the outer layer of fibers and plays a protective role. It consists of individual scales, which are plates that fit tightly to each other and are attached at one end to the fiber rod. Each scale has a protective layer;

The cortical layer is the main layer of the fiber and includes a number of longitudinally arranged spindle-shaped cells that form the body of the hair;

In the middle of the fiber there is a core layer, which consists of loose thin-walled cells filled with air bubbles. The core layer, without increasing strength, only contributes to an increase in the thickness of the fiber, ᴛ.ᴇ. deterioration in its quality.

Given the dependence on the thickness and structure, the following main types of wool fibers are distinguished: fluff, transitional hair, awn, dead hair.

Down is a thin crimped fiber that has two layers: scaly, consisting of ring-shaped scales, and cortical.

The transitional hair is somewhat thicker than down. It consists of three layers: squamous, cortical and discontinuous core.

The awn is a coarse straight fiber that has three layers: scaly, consisting of lamellar scales, cortical and solid core.

Dead hair is the thickest, coarsest, but most fragile fiber. It is covered with large lamellar scales, has a narrow cortical ring and a very wide core. The cross-sectional shape is most often flattened, irregular. Dead hair is a tough, brittle fiber with little strength and poor dyeability.

Wool, consisting mainly of fibers of one type (down or transitional hair), is usually called homogeneous, and containing fibers of all of the listed types - heterogeneous. The more fluff in heterogeneous wool and the less dead hair, the higher its quality.

In terms of hygroscopicity, wool surpasses all fibers. It slowly absorbs and evaporates moisture. Under the influence of moisture and heat, the keratin softens and the elongation of the coat increases to 60% or more.

When drying, wool gives maximum shrinkage, in connection with this, products made from it are recommended to be dry-cleaned.

Wool is resistant to all organic solvents.

Concentrated acids destroy wool fibers: nitric acid causes yellowing, sulfuric acid charring.

In terms of light fastness, wool surpasses all natural fibers.

In the flame, the wool fibers are sintered, forming a black ball at the end, which is easily rubbed, emitting the smell of a burnt feather. When taken out of the flame, they do not burn.

The group of woolen fabrics includes: twill, broadcloth, tweed, boston, carpet coat, cheviot, duvetin, etc.

Silk. Silk threads are obtained from the cocoons of silkworm caterpillars. The silk group includes such fabrics as veil, chiffon, crepe de chine, satin chesucha, crepe, crepe georgette, toile, fai, taffeta, brocade, foulard, etc.

Traditionally, silk is considered one of the most expensive types of fabric. Products made of silk fabric are very light, durable, beautiful. They have a pleasant shine, well regulate body temperature. The disadvantages of silk include the fact that the fabric is very wrinkled and sensitive to ultraviolet rays. Often, another kind of fiber is added to natural silk fiber to obtain new interesting textures and various spectacular weaves.

Natural silk is called thin continuous threads secreted by the glands of silkworm caterpillars when curling a cocoon before pupation. Main Of industrial importance is the silk of the domesticated silkworm, whose caterpillars are fed with the leaves of the mulberry tree (mulberry).

The length of the cocoon thread is up to 1,500 m, and the unwound thread is 600-900 m. The relative breaking load of the cocoon thread is somewhat less than that of cotton, the breaking elongation is 2-2.5 times greater. The strength of natural silk in the wet state is reduced by 5-15%.

In terms of light fastness, natural silk is inferior to all other natural fibers. The combustion of the fiber occurs similarly to the combustion of wool.

The structure and properties of natural fibers. - concept and types. Classification and features of the category "Structure and properties of natural fibers." 2017, 2018.

Fibers are composed of substances that belong to high-molecular compounds - polymers. Of the substances found in nature, polymers include, for example, cellulose - the main part of plant fibers, keratin and fibroin - the main protein substances that make up wool and silk.

The most important natural textile fiber is cotton. These are the hairs on cotton seeds. At ginneries, raw cotton, which is a large number of cotton seeds covered with cotton fiber, is cleaned from plant impurities (parts of bolls, leaves, etc.) that have fallen during the cotton harvest, and then the fibers are separated from the seeds on special machines - fiber separators. Then the fiber is pressed into bales.

The length of cotton fibers is different - from 10.3 to 60 mm. Cotton fiber is thin (average thickness - 20-22 microns), but very durable. It's cheap and paints well.

From cotton, a fine, uniform and durable yarn is obtained and a wide variety of fabrics are made from it - from the finest batiste and voile to thick upholstery fabrics.

Textile fibers are also obtained from the stems and leaves of plants. Such fibers are called bast and leaf. They are thin (linen, ramie) and coarse (hemp, jute, etc.). Various fabrics are made from fine fibers, ropes and ropes are made from coarse fibers.

Wool has long been known to people. The main mass of wool (up to 95%) is given by sheep. In terms of its significance for National economy wool is second only to cotton. It has many very valuable properties: it is light, conducts heat poorly and absorbs moisture well.

Sheep are sheared either once a year - in the spring (while the wool is removed in a continuous layer - a fleece), or twice - in spring and autumn. When sheared in autumn, the wool is obtained in the form of shreds.

At primary processing factories - wool washers - wool is freed from dirt and impurities. Fleece, identical in its properties, is combined into common batches. Wool is used to make smooth yarn, as well as fluffy, thick yarn. On the surface of a smooth fabric, a pattern of interlacing of threads is clearly visible. Such fabrics are strong, light, wrinkle a little. Various clothes are sewn from them - dresses, suits, coats. From fluffy and thick yarn, heavier fabrics (cloth) are produced, having a greater thickness and a fleecy surface.

Wool is the only natural fiber from which various felts and other elastic and dense materials can be obtained by felting it.

Natural silk is obtained in this way. When the time comes for the silkworm caterpillar to turn into a chrysalis in order to become a butterfly, it releases a thin thread from itself, attaches it to a dry branch and weaves a shell-nest from this thread - a cocoon. Silk is made from these finest cocoon threads.

Silk cocoon threads consist of 2 silk filaments glued together with a special substance - sericin, their length reaches 400-1200 m. If you let the chrysalis turn into a butterfly and leave the cocoon, holes will appear in the silk shells. Such cocoons are very difficult to unwind. Therefore, the pupa is killed by treating the cocoons with hot air, and then, so that they do not rot, they are dried. Since the silk thread is very thin (its average thickness is 25-30 microns), when unwinding, the threads of several cocoons (from 3 to 10) are connected. In this case, the threads are firmly glued together with sericin. This thread is called raw silk.