How does polyester burn? How to determine the composition of yarn by burning

The appearance, elasticity of fabrics, cutting resistance, frayability, extensibility, ability to iron and pull, and choice of WTO mode depend on the fibrous composition.

Depending on the fibrous composition, fabrics are divided into homogeneous, heterogeneous, mixed and mixed-heterogeneous.

HOMOGENEOUS fabrics consist of the same fibers, for example wool, cotton, silk, etc.

HETEROGENEOUS fabrics consist of thread systems of different types of fiber, for example, warp - cotton, weft-wool; warp - viscose, weft - acetate.

MIXED fabrics are fabrics that contain different fibers in the warp and weft, mixed during the spinning process. For example, the warp and weft are wool with lavsan. Mixed fabrics include fabrics made from twisted non-uniform threads.

MIXED-HONOGENEOUS - these are fabrics that have one system of threads that is uniform, and the second from a mixture of fibers. For example, the warp is cotton, and the weft is a mixture of wool with staple viscose fiber. Based on the presence of more valuable fiber, heterogeneous, mixed and mixed-heterogeneous fabrics are usually called half-wool, half-linen, half-silk. Half-silk fabrics usually have a silk warp and a cotton weft. Pure wool fabrics can contain up to 10% chemical fibers.

DETERMINATION OF FIBROUS COMPOSITION OF TISSUE

You can determine the composition of the tissue using the senses: touch, vision, smell in the following sequence:

By appearance
Touch and wrinkleability
By type of warp and weft threads
According to the nature of fiber combustion

When determining the fiber composition, first of all, you need to pay attention to the color, gloss, thickness, and density of the fabric. Then work on creasing: gather the fabric into folds and squeeze it tightly in your fist, after 30 seconds release it and smooth it with your hand. Next, consider the warp and weft threads. Each thread must be examined separately. Then trace the combustion pattern of the fibers. Burning tissue with an “angle” leads to erroneous results.

Signs of determining the composition by appearance:

Cotton fabrics are usually thinner than linen; cotton gives them a special matte finish, while linen fabrics have a shine. Linen fabrics are often natural color: Gray linen fabrics have a grayish or greenish tint. Raw cotton fabrics have a yellowish tint.

Wool fabrics recognized by the woolly surface, piled in cloth fabrics and with an open weaving pattern in combed fabrics; The surface of fine cloth fabrics is smooth, while coarse hairs are visible on coarse cloth fabrics. Wool-blend fabrics mixed with cotton are characterized by some fading.

Fabrics made from natural silk are easily recognized by their thin thickness, smooth surface and soft, deep shine.

Based on the nature of creasing and the feel of fabrics, they are determined as follows:

Linen always gives the impression of coldness and rigidity to the touch, cotton - softness and warmth; Linen fabrics, as a rule, are heavier than cotton and have almost no stretch either along the warp or weft.

Pure wool fabrics, when crumpled, either do not form wrinkles, or wrinkles easily disappear; on fabrics mixed with viscose or staple fiber, angular folds remain that do not disappear or disappear slowly.

Fabrics made from natural silk are light, soft to the touch and wrinkle relatively little; artificial silk fabrics are heavier, harsh to the touch and, when crumpled, leave folds that are difficult to straighten out.

To determine the composition of the fabric by the type of warp and weft threads, you need to remove 2-3 threads from each system, put them side by side and compare the appearance. If the yarn is twisted, you need to unwind it into separate threads and look through each thread.

Wool is recognized by its peculiar crimp and slight sheen; cotton by its matte, thin, short fibers; staple fiber by its thin, longer, non-crimped fibers with increased shine.

Determination of the fibrous composition by the nature of the rupture of the warp and weft threads:

When a cotton thread breaks, a fluff of short, very thin fibers forms at its end; at the end of a torn linen thread, a tassel is formed from straight, longer, coarser fibers of unequal thickness.

The wool fibers at the broken end of the yarn are recognized by the presence of crimp; if the yarn is mixed (with a mixture of cotton or staple), the cotton differs in its short, thin matte fibers, the staple fibers are long, shiny, as if flaccid.

When a natural silk thread breaks, the individual fibers remain connected, while in threads made from artificial and synthetic fibers, especially with a slight twist, the fibers at the end scatter, forming a fluffy tassel that “sticks to the fingers.”

The strength of natural silk does not change after soaking, the strength of viscose and copper-ammonium fibers after soaking decreases by 50%, and the strength of acetate decreases by 30%.

By the nature of the burning of fibers, the fibrous composition of fabrics can be determined quite accurately:

Black yarn sinteres in the flame, but does not burn when removed from the flame. A black cake forms at the end of the thread. The smell of burnt feathers or horn. If wool yarn contains 10% plant impurities, then a luminous ember is formed behind the sintered ball, which quickly goes out, leaving a layer of gray ash. If the yarn contains 15-20% impurities, then 1.5-2 cm of thread burns, then the flame goes out. If the yarn contains more than 25% plant impurities, then the entire thread burns out and loose gray ash remains. If wool yarn contains nitron or lavsan, then it burns with a yellow, smoky flame, forming a hard skeleton of the thread, the smell of a feather. If the yarn contains up to 10% nylon, it burns like pure wool, but a ball remains at the end, which does not rub well.
Cotton fibers burn with a yellow flame and burn completely, forming gray ash. The smell of burnt paper.
Linen burns just like cotton.
Natural silk burns similarly to wool.
Rayon fibers burn faster than cotton.
The acetate fiber burns quickly with a yellow flame, leaving a melted ball at the end.
Nylon fibers burn with a bluish flame, forming a brown melted ball.
Lavsan melts, then slowly burns with a yellow, smoky flame.
Nitron, acrylic (polyacrylonitrile fibers) melt and burn with a yellow flame with flashes.

In the laboratory method of determining the fibrous composition of tissues, microscopes and chemical reagents are used. To determine the composition using this method, you need to have a good knowledge of the structure of the fibers and their chemical properties. The laboratory method gives a more accurate result than the organoleptic one, but in practice it is more often used last method as more accessible.

Loose with protruding fibers. The fibers are crimped.
Actions of the reagents: From vegetable oil It's getting dark.
Character of combustion, melting: Burns with a fast, even flame. The ash is light gray, crumbling.
Burnt paper.

Linen fabric

Physical properties and appearance: More dense than cotton. The fibers are longer and smoother.
Actions of the reagents: Vegetable oil makes it transparent.
Character of combustion, melting: Same as for cotton.
Odor when burning, melting: Same as for cotton.

Wool

Physical properties and appearance: Rough, elastic fibers.
Actions of the reagents: Dissolves in alkalis.
Character of combustion, melting: It burns poorly, forming a dense sintered ball.
Odor when burning, melting: Burnt feather.

Natural silk

Physical properties and appearance: Smooth, shiny fiber that crunches when crushed.
Actions of the reagents: Dissolves in alkalis.
Character of combustion, melting: Same as for wool.
Odor when burning, melting: Same as for wool.

Viscose

Physical properties and appearance: Smooth shiny fiber.
Actions of the reagents: When wetted with sulfuric acid it turns red.
Character of combustion, melting: Same as for cotton.
Odor when burning, melting: Same as for cotton.

Acetate wool or silk

Physical properties and appearance: Smooth shiny fiber.
Actions of the reagents: When moistened with acetone, it dissolves and becomes similar to glue.
Character of combustion, melting: First it melts and then burns, forming a brittle balloon.
Odor when burning, melting: Sour.

Lavsan

Physical properties and appearance: Very similar to wool.
Actions of the reagents: Not wetted by water.
Character of combustion, melting: Melts without flame, forming a solid ball.
Odor when burning, melting: Without smell.

Capron

Physical properties and appearance: Very similar to silk, but crunchy.
Actions of the reagents: Dissolves in acid.
Character of combustion, melting: Melts without flame, forming a soft ball.
Odor when burning, melting: Without smell.

The article is based on material from the book "Housekeeping Secrets. A Universal Reference Book", authors B.V. Berkov, G.I. Berkova, PUBLISHING HOUSE “Ural LTD”, MOSCOW 1972.

There are a number of ways. Of course, the most reliable method is the laboratory method. It includes microscopic and chemical analyses. However, most often we have to resort to the organic method - determining the fabric by eye, touch, crumpling, stretching, tearing, burning.

By appearance linen fabric more shiny, cotton - matte.

The threads of the cotton fabric are even, while the threads of the linen fabric are thickened in places.

To the touch: linen fabric is more rigid, and when applied to naked body gives a feeling of cold.

For crumpling: linen fabric produces stiff folds that are difficult to straighten out. Linen fabric has almost no stretch either in the warp or in the weft, while cotton fabric stretches in the weft.

For thread break: Linen will have pointed ends, while cotton fabric will have fluffy and smooth ends.

For combustion: Linen fabric gives off almost no odor, and when cotton fabric burns, a sharp fire and acrid smoke are released.

In the same way, one can unmistakably distinguish natural silk from artificial And wool from wool mixture and mixed fabrics.

Approximately: artificial silk has a sharp metallic sheen, while natural silk has a soft matte finish.

To the touch: artificial silk is hard, while natural silk is soft. Woolen fabrics, depending on the nature of the fiber and its structure, can be very soft, semi-coarse and coarse.

For crumpling: artificial silk produces a stiff fold that does not straighten out easily. Wool fabrics are the most resilient and elastic. Pure wool fabrics are soft and, once wrinkled, straighten out slowly and completely. Semi-coarse and coarse pure wool fabrics - after crumpling, they give quick and sharp straightening.

To break: natural silk breaks with difficulty, but artificial silk breaks easily, especially when moistened, when it loses up to 70% of its strength. When a thread of artificial silk breaks, it crumbles into separate fibers, while threads of natural silk break off evenly, without crumbling. Wool thread It does not tear immediately, but first stretches significantly.

For combustion: natural silk is sintered into a ball and goes out, while artificial silk burns out completely. When the wool burns, it sticks together into a ball, goes out, and smells like burnt horn. If the light runs along the thread with the same smell of horn, this is a clear sign of the presence plant fibers or artificial silk. If the thread burns down to 1-2 cm and then goes out, also emitting a characteristic odor, then the presence of plant fibers or artificial silk makes up a significant percentage.

Wool blends for crushing and stretching do not give the same indicators as those inherent in fabrics made from pure wool.

Nylon is a polyamide fiber.

Nylon is a strong fiber (45 – 70 CH/tex).

· In terms of strength it is second only to glass. When wet, the strength does not decrease (10 - 15%).

· Elongation is 20-25%, when wet it increases by 3-5%.

· Elasticity is a distinctive feature of p/a fibers: with small tensile forces, the reverse deformation of nylon is 90-95% of the total elongation.

· Nylon is characterized by very high resistance to abrasion and repeated deformation. The abrasion resistance of nylon is taken as 100%.

· The heat resistance of nylon is low t=65 0 C, t 100-110 0 C.

· The light resistance of nylon is also insufficient; to increase heat and light resistance, stabilizers are added to the composition of polyamides.

· Chemoresistant. Withstands acids and alkalis up to medium concentrations.

· Resistant to microorganisms.

The disadvantages of nylon include low hygroscopicity (4-5%), reduced adhesion, poor colorability, increased rigidity and electrification.

Combustion . When brought to the flame, it melts, then lights up with a weak bluish-yellow flame, spreading white smoke and the smell of sealing wax. When removed from the flame, the combustion stops and a solid gray ball solidifies at the end.

MODIFICATIONS OF P/A FIBERS

SHELON-1– is a profiled thread with a complex cross-sectional shape, which makes it possible to create open channels (capillaries) and porosity in the thread. This thread structure significantly improves its hygroscopic properties. Fabrics made from shelon-1 threads are similar in properties to fabrics made from natural silk. Products made from them are pleasant to wear and do not cause skin irritation, because... porous fiber provides good ventilation.

TRILOBAL– physically modified complex-profile polyamide thread. Gives products softness, silkiness, increased porosity, which increases the breathability and moisture conductivity of materials.

CAPRYLON AND MEGALON– chemically modified polya fibers, which are obtained by side grafting of a copolymer containing hydroxylone groups. Such fibers are close to cotton in hygroscopicity (5-7%) and surpass it in strength and abrasion resistance. The susceptibility of fibers to dyes is increased.

LAVSAN

Lavsan – polyester fiber

The starting material for its production, polyethylene terephthalate, is a product of the interaction of dimethyl terephthalate and ethylene glycol.

Lavsan is a strong fiber. The breaking load of conventional fibers reaches 40-50 CH/tex. When wet, the strength remains virtually unchanged.
The elongation is 20-25%.
The fibers are highly elastic: when stretched up to 5-6%, the elongation is completely reversible, so lavsan fabrics do not wrinkle after washing and cleaning. Lavsan is the most elastic fiber.
Lavsan is highly resistant to abrasion (second only to polyamide fibers).
The fiber is resistant to light. It is also positive that when exposed to light, products made from polyethylene fibers do not change their color to the same extent as others.
The fiber is heat-resistant, t=180 0 C, tto=140-160 0 C.
Resistance to acids and oxidizing agents is higher for polyester fibers than for polyamide fibers. However, the fibers are not sufficiently resistant to alkalis, especially when heated.
Lavsan has a slight shrinkage, so the products have a stable shape.
Has high dielectric properties.
Resistant to microorganisms.

DISADVANTAGES: low hygroscopicity (0.5%), high electrification, poor paintability, pilling.

Combustion : When brought to a flame, it shrinks, melts, then ignites. Burns with a calm yellowish flame with the release of black soot. A hard black ball hardens at the end.

MODIFICATIONS: complex-profile polyethylene thread shelon-2.

NITRON

Nitron – polyacrylonitrile fiber (PAN). It is obtained mainly in the form of staple fiber.

Nitron is a very light, soft, wool-like fiber that has low thermal conductivity, the indicators of which are close to the thermal conductivity of wool. Nitron is inert to pollutants, so products are easy to clean.

· Nitron – strong fiber (32-39 CH/tex). Due to low hygroscopicity in the wet state, strength almost does not lose (2-5%).

· Elongation depends on the degree of drawing and ranges from 16 to 35%.

· Good elastic properties.

· Nitron is the most light-resistant fiber. After a year of aging in the open air, nitron retains 80% of its strength, and cotton - 5%.

· Heat resistance 180 0 C, t WTO = 140-160 0 C.

· The fiber is resistant to microorganisms and is not damaged by moths.

· Nitron is resistant to oxidizing agents and organic acids, but unstable to concentrated solutions of alkalis and inorganic acids.

Disadvantages include:

· Low hygroscopicity (2%).

· Poor colorability.

· Low abrasion resistance.

· Significant electrification and pillability.

Combustion : When brought to the flame, it first shrinks, melts, then burns intensely, with flashes, highlighting a large number of black soot. After the combustion stops, an irregularly shaped influx remains.

Compared to other synthetic fibers, nitron has the advantage of being easy to modify, which makes it possible to give them specific properties over a wide range: dyeability with dyes of various classes, antistatic, non-flammable, porous, transparent, increased strength, stable crimp, adhesion (scaly fibers), etc. d.

CHLORINE

Chlorine refers to polyvinyl chloride fibers. The raw material is vinyl chloride, obtained from ethylene or acetylene by saturating them with chlorine.

Chlorine differs from other chemical fibers in its lack of shine.

· Has less strength than other synthetic fibers. When wet, the strength does not decrease.

· Elasticity is lower than other synthetic fibers.

· Low heat resistance (t=70 0 C), when heated to t=90-100 0 C, the fiber begins to deform.

· Low light fastness.

· Non-hygroscopic fiber (0.1%).

· High chemical resistance. Chlorine is the most chemical-resistant fiber (dissolves in chloroform and perchlorethylene).

Combustion The fiber is non-flammable. When brought to the flame, it shrinks greatly, chars, but does not burn, and emits the smell of chlorine.

Application

1. Therapeutic underwear for patients with rheumatism and radiculitis (since chlorine is capable of accumulating electrical charges on its surface).

2. Overalls for workers in the chemical industry (since the fiber is very chemical resistant).

3. Overalls for fishermen and foresters (since chlorine is resistant to microorganisms and does not absorb water).

VINOL

Vinol belongs to the class of polyvinyl alcohol fibers.

Polyvinyl alcohol fibers are produced in small quantities. They are produced in the form of staples (for household products), high-strength threads for technical purposes and special-purpose fibers - water-soluble, ion-exchange, bactericidal.

· A special feature of vinol is its high hygroscopicity (8%), due to the large number of hydroxyl groups, and good colorability.

· Vinol is a strong fiber (30-40 CH/tex).

· Elongation of regular staple fiber is 30-35%.

· Satisfactory elastic properties.

· High abrasion resistance (vinol is second only to polyamide fibers in this indicator).

· Heat-resistant fiber (t=180 0 C). Withstands boiling washing, hot ironing, and dries quickly.

· Thermal conductivity is close to wool.

· Light fastness is good.

· Under the influence of water, strength decreases by 15-25%.

· Resistant to alkalis, but strength decreases when heated.

· Dissolves in concentrated acid solutions in the cold.

When introduced into the flame, it shrinks, then burns with a yellowish flame. After the combustion stops, a solid influx of light brown color remains.

SPANDEX (LYCRA)

Spandex is a polyurethane fiber.

Distinctive feature polyurethane threads – their high elasticity (elongation at break can be 800%). When elongated by 300%, the proportion of elastic elongation is 92-98%. Polyurethane threads give textile materials high elasticity, resilience, dimensional stability, and wrinkle resistance. They are highly resistant to abrasion, mold and sweat, are easy to paint, and are resistant to chemicals and light weather.

However, spandex fibers have a low breaking load, are not hygroscopic (0.8-0.9%), and have low heat resistance (80-100 0 C). When heated to 150 0 C, thermal destruction begins, the threads turn yellow, and their rigidity increases.

They burn like lavsan.

Application. Polyurethane threads are used to make elastic fabrics and knitwear. They act as frame rods around which threads from other fibers are wound.

Although we ourselves sometimes do not mind being deceived. In pursuit of a low price, instead of quality materials, we often give preference to cheaper fabrics. At best, such savings result in discomfort when wearing, at worst - allergies and other health problems.

What fabrics should you buy from when building your wardrobe? How to avoid falling for the bait of unscrupulous sellers? Is it possible to determine the composition of a thing without laboratory tests? We talked about this and much more with Galina Skripko, Candidate of Technical Sciences in the specialty “Technology of Textile Materials, Garment and Knitted Products” on AiF.ru.

It's not cold in winter, it's not hot in summer

Natalya Kozhina, AiF.ru: Galina Alekseevna, what is “healthy clothing”, which in fact should make up our wardrobe?

Galina Skripko: Clothing is considered healthy if the textile material is made from natural raw materials (cotton, wool, flax, natural silk, etc.) or from material with a high content of it.

It is always comfortable to wear such clothes: it is not cold in winter, and not hot in summer, because the material containing natural fibers, has unique property- keep warm for a long time, slowly cooling, and vice versa, keep cool, slowly warming up. Such material does not have a negative effect on the human biofield, since natural fibers are not capable of accumulating static tension. Due to the high breathability and ability of the material to absorb moisture, the clothing becomes hygienic.

N.K. “AiF.ru”: Is it possible to determine good and high-quality fabric only by its price?

G.S.: No. The initial price for the product is determined by the manufacturer, the final price is determined by the distributor. Both focus on consumer demand when determining prices. In this case, less fashion clothes, although of high quality, can be offered to the buyer at a lower price than a branded one made from lower quality raw materials.

Sometimes, in order to increase sales, manufacturers and distributors of textile products directly deceive the buyer by indicating deliberately false information about the fiber composition of the material on the product label or price tag.

N.K. “AiF.ru”: If price is not an indicator, then what factors can help determine the quality of the fabric?

G.S.: Subjectively, the quality of a material can be determined by appearance and touch. Some natural fibers have a characteristic odor. For example, wool has its own smell, it is difficult to describe it, but when we smell it, we remember it. Why does wool smell? Because she has fatliquoring agents, these products have such a specific smell. Cotton smells fresh.

The naturalness of modified fabrics can be determined by external signs difficult even for a professional. Thus, fabric or knitwear made from mercerized cotton (Mercerized cotton is cotton that undergoes alkali treatment. The fiber becomes thinner, shrinks less and is more even) in appearance differs little from material made from polyester cotton-like fiber.

In everyday conditions, to determine the type of clothing fibers, we can recommend a method based on the characteristics of combustion and the characteristic odor of the combustion residues of the fibers. For example, cotton yarn burns quickly, leaving a burnt paper smell; the burnt residue is easily crushed between your fingers. Yarn made from polyester fibers is characterized by rapid attenuation, the burnt residue has the appearance of a solid black ball, and there is no smell. The presence of wool or natural silk in the yarn is determined by the characteristic smell - burnt horn. If the combustion residue does not crumble when rubbed between your fingers, then the yarn contains synthetics.

N.K. “AiF.ru”: Often in a store you can see things made of 100 percent cotton (i.e., identical in composition), but at the same time they will feel completely different to the touch, why? In this case, what fabric should you choose?

G.S.: Everything is correct. Same in fibrous composition textile materials can have different textures. Texture is determined by the density of the fabric and its thickness. The density of the fabric depends on the density and type of weave of the yarn, and the thickness depends on the thickness of the yarn. If speak about cotton fabrics, then their range is very wide: calico, chintz, satin, crepe, cashmere, flannel, flannel, cambric, etc. The thinnest and most expensive fabric is cambric. It is made from fine, tightly spun cotton yarn, which is obtained from high-quality long-staple cotton. When assessing the quality of the fabric or material of the product, you should carefully examine its surface for defects: thickening of the yarn in limited areas, fluffiness (the presence of small lumps of tangled fibers on the surface of the fabric), knots, violations in limited areas of the density of the fabric due to vacuum or compaction between the interweaving of threads , the presence of distortions in the direction of the threads, uneven coloring, displacement of the pattern, etc.

Fabric and knitwear, the yarn of which is made from high-grade fiber, has a smooth surface. The denser the material, the less it deforms during product operation. However, dense material does not mean thick.

W, CO, CVI - designations that are important to know

N.K. "AiF.ru": What fabric should be used when creating a children's wardrobe?

G.S.: The production of children's clothing requires its compliance with sanitary and hygienic rules and regulations (SanPin), according to which children's underwear up to size 32 and hosiery up to size 16 should not contain synthetic fibers. It is allowed to replace part of the cotton with artificial fiber - viscose:
- up to 10%, for toddler underwear (up to size 28) and hosiery up to size 16;
- up to 30%, for children's underwear up to size 32.

N.K. “AiF.ru”: What fabric composition is ideal for underwear and swimwear?

G.S.: Underwear made from 100% cotton jersey is considered ideal. To increase the elasticity of knitwear, it is permissible to add elastic thread (elastane, spandex) to the yarn, the content of which should not exceed 2-1%. Underwear made from such knitwear is not only hygienic, but also more comfortable, as it fits tightly to the body.

N.K. “AiF.ru”: Galina Alekseevna, please tell us about the symbols that are often used on labels, what do they mean?

G.S.: The designation of raw materials must contain the full name of the types of fibers or their abbreviated designation. The abbreviated designation is mainly used by foreign manufacturers. For example, cotton (cotton) - CO, ALG; flax (flax) - Li; wool (wool) - W or WP, WL, WA (alpaca, llama, angora wool): silk (silk) - SE. For artificial chemical fibers the following designations are used: viscose (viskose) - Vis, VI; high-modulus fiber (Siblon, Modal) - CVI, MD; acetate - AC. Synthetic fibers designate: polyester (polyester) - PE, PE, PES, PL; polyacrylonitrile (acrylic) - PAN, PAC, RS; polyamide (polyamide) - PA, RA; polyurethane (polyurethane, elastane) - PU, PU, EA.

In duplicated canvases, the composition of the raw material is indicated separately for each layer.

When secondary raw materials are included in the material, the words “recycled raw materials” and its type must be indicated.