Wool fiber. How to determine the composition of yarn by burning How lavsan burns

How to distinguish natural fabric from synthetics? This problem especially often arises when purchasing bed linen. People out of habit believe that if it is calico, it must be pure cotton. But, whether it is calico or poplin, this definition does not refer to the quality of the thread from which the fabric is woven, it is the name of the weaving technology. And, as you understand, you can weave it from any thread, even from wire.
Therefore, in order not to feel deceived, you need to know how to check what fiber a product is made of.

The first test is tactile sensation. Even if the fabric is natural, you don't have to like it. And this factor plays an important role when choosing. For example, for many, pure flax fiber seems coarse; they also often talk about thick and high-quality calico.

Satin seems thin to many, although it is completely opaque, like calico, comfortable, and a pleasure to sleep on. Therefore, relying only on tactile sensations, you can just buy soft, pleasant, velvety, but synthetic underwear.

There is a simple home way to check the naturalness of the thread - you need to set it on fire.

If you buy clothes, then, as a rule, there is a spare piece of fabric, you can conduct an experiment on it.

WITH bed linen more complicated, it does not come with a fabric sample, so you will have to be smart about how to check whether the fabric is actually natural, as stated by the manufacturer.

So, if you have a piece of fabric or at least a thread, let's start doing research. To do this, we need a safe place, matches, and the ability to ventilate the room.

How to distinguish natural fabric from synthetic

Cotton fiber burns with a light flame, burns very quickly and does not leave a strong odor, to some it slightly resembles the smell of burnt paper. There is very little ash left, and it is completely weightless.
Flax also burns quickly, leaving very little bright gray ash, but leaves no odor.
Pure wool thread burns very slowly and reluctantly, eventually shrinking into a ball, filling the space unpleasant smell resembling burnt hair or feathers.
Artificial wool burns very quickly and beautifully - the flame is blue, and the smell will be as if paper was set on fire.
Viscose obtained artificially from wood, i.e. cellulose is considered a natural fabric. Viscose burns very quickly, but smolders for a long time, actively smoking and emitting the smell of burnt cotton wool. The remaining gray ash crumbles well.

How to distinguish natural silk from artificial silk

Natural silk does not want to burn at all, no matter how hard you try. The thread will shrink into a black knot, and the flame will immediately go out. The smell is vaguely reminiscent of burnt keratinizations (nails, claws, horns), if you have ever heard such a smell.

It is very easy to distinguish artificial silk from natural silk. It burns well and quickly, without crackling or odor.

When buying a silk item, you will not start a fire in the store, so just squeeze the fabric in your hand, unclench your fist after a while and see if the fabric is wrinkled. Artificial silk will have noticeable creases, while natural silk will wrinkle quite a bit.

A characteristic feature of all burnt natural samples is the ability to easily crumble combustion residues. Artificial thread does not provide such an opportunity, in addition, artificial material When burning, it emits a slightly sour smell.

Acetate silk can melt in acetone, which cannot be said about natural silk.

IN lately A lot of mixed fabrics have appeared, containing natural thread in combination with artificial thread. The manufacturer is required to indicate the percentage of all types of threads - these can be acrylic, acetate fiber, lavsan and other artificial additives. If you set fire to such fabric, the flame will be similar to the thread that contains the most of it. The smell will also determine the composition, but the remains of combustion cannot be easily crushed.

Mixed fabrics used in the production of bed linen are, as a rule, very pleasant to the touch, have a durable color, practically do not wrinkle and last a long time if used correctly.

Be able to distinguish natural fabric from artificial It is also necessary to properly care for the product.

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 distinguishing feature 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 their 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 large number 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, 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.

The chemical industry produces large quantities of chemical fibers used to make clothing and other goods. When degreasing with chlorinated hydrocarbons, some of the fibers may be completely or partially dissolved, such as fibers obtained from vinyl chloride. Some types of products undergo such shrinkage during the degreasing process that they completely lose their consumer properties: for example, a size 48 knitted sweater becomes size 30. Products made from silk acetate may be destroyed during the process by the use of acetone, acetic acid and other reagents. All this caused the need to recognize the fibrous composition of products.

Fibers can be recognized by the nature of their combustion, by their solubility in various solvents, by their dyeability, as well as by their melting point, fluorescence and luminescence.

When examining fibers using a microscope, they are examined both in the longitudinal and transverse directions (transverse sections), comparing those studied with standards.

Despite the fact that there are many fiber recognition methods, most of them are unsuitable for work in factories, as they require a significant investment of time, large samples of the materials being studied, or the use of special equipment.

Express fiber recognition methods applicable to collection points and dry cleaning factories

Recognition of fabric fibers by combustion pattern

The method of recognizing fibers by burning them is the simplest. Using it, you can determine a whole series fibers quite accurately. When burning fibers in the flame of an alcohol lamp or burner, they take into account the nature of combustion (quiet flame or combustion accompanied by melting), the type of flame (smoking or not), the smell, the type of residue after combustion, and then make a conclusion about whether the fibers belong to one class or another.

	Sunbathing	Character	Behavior outside the flame	Smell when burning	Character
Cotton, viscose fiber		Burn quickly without soot or melting			Gray ash
Natural silk, wool		Burn moderately without soot or melting			Fragile black ball
Acetate		Burns moderately, without soot, melts		Vinegar	Dark brown ball
Nylon, nylon		Burn moderately without soot, melt			Hard, dark, shiny ball
		Burns quickly with soot and melting
		doesn't melt			Dark, matte, loose ball
Polypropylene		Burns quickly, without soot, melts			Non-fragile black ball
		with soot and melting			Fragile black ball

Recognition of fabric fibers by solubility

Fibers can also be recognized by their solubility in different solvents.

Processing sequence	Solvent
Processing sequence	Solvent	dissolve	Do not dissolve
	Doorman's Reagent	Viscose, copper-ammonia	Acetate, polyester, polyamide, polyvinyl chloride, polyacrylonitrile
	Acetic acid, glacial, cold	Acetate	Polyester, polyamide, polyvinyl chloride, polyacrylonitrile
	Hydrochloric acid cold	Nylon, anide (when the solution is diluted with water, a precipitate forms)	Polyamide (undecane), polyester, polyvinyl chloride, polyacrylonitrile
	Nitric acid, concentrated cold	Polyacrylonitrile (nitron)	Polyamide (undecane), polyester, polyvinyl chloride
	Concentrated cold sulfuric acid	Polyamide (undecane), polyester (lavsan)	Polyvinyl chloride (chlorine)

Recognition of fabric fibers by dyeability

For undyed fibers, it is possible to recognize fibers by their dyeability in a dye mixture. The mixture is prepared by dissolving the following dyes in 1 liter of water, g:

Chloramine orange 1.0

Chloramine yellow 2.0

Diamond blue FFR extra 1.0

Eosin extra 1.0

Cellitone pink R 0.5

Dispersant 1.0

Celliton pink R is dissolved in water at 50-60° C. The remaining dyes are dissolved at boiling. The fiber sample to be analyzed is placed in a boiling dye solution for 3 minutes. The samples are then selected, washed cold water and boil in a bath containing 1 g/l of dispersant for 1 minute. As a result of dyeing, the fibers obtain the following color:


Natural silk
Woolen	Dark purple
Cotton	Gray-yellow
Casein	Red-violet
Mercerized cotton	Bright yellow
Copper-ammonia	Orange-brown
Acetate
Polyamide
Polyvinyl chloride	Colorless

There are also methods from NITHIB and MIT.

The easiest way to determine what fiber a purchased fabric is made from is to use a combustion test. Natural fibers burn and char, turning into ash. Synthetic ones melt, leaving a hard lump. Cotton and linen fabrics (from plant fibers), as well as wool and silk (from animal fibers) burn equally.

Acetate and acrylic fabrics

They burn and melt in the flame and outside it, when they have already been removed from the flame. After burning, a solid lump remains. Acetate fabric can be easily identified by placing a piece of it in nail polish remover: the acetate will dissolve in it.

Polyester, nylon and other synthetic materials

They do not burn, but only melt in the flame or short time after removing it with a chemical smell, leaving a hard lump.

Wool and silk

They burn slowly, charring and curling into rings. Sometimes they only burn while in the flame. They smell strongly and not very pleasantly, like burnt hair or feathers, and leave brittle ash.

Cotton and linen

They burn quickly followed by a glow. When burned, they smell like burnt paper, forming soft gray ash.

It is usually not difficult to distinguish synthetic fabric from natural fabric in a store. Just read the composition of the material on the price tag, or ask the seller. In addition, natural fabrics are often much more expensive than synthetics. However, there are quite a lot of situations where the composition of the tissue is unknown. How can you find out what the fabric is made of? Read under the cut.

Serious doubts regarding the composition of the fabric may arise if you buy a piece secondhand, or if you discover large deposits of fabric of unknown origin at home. :) Sometimes I doubt the composition of the fabric even in the store. For example, if the cotton feels too silky or stretchy. Or if it doesn't wrinkle at all.

But why is it so scrupulous to find out the true composition of the material? Firstly, to understand the fabric you have chosen. And secondly, . I am one of them. I feel hot in synthetics, but the worst thing is allergic reactions. Of course, there must be an integrated approach, and nutrition, as well as cosmetics, should also be as natural as possible. But clothing can be a big factor in combating unpleasant skin reactions.

In my opinion, with experience, many fabrics can be identified by touch. For example, natural wool has a very recognizable smell and is easy to recognize by touch. But, of course, you can always run into a very well-made synthetic fabric. How to determine the composition of the fabric? For this we need... Matches or a lighter. Yes, yes, we will check the composition of the fabric this old-fashioned way.

For my experiment I selected:

Viscose lining fabric.

Unnamed fabric, synthetic in my opinion.

Unnamed chiffon, similar to synthetics.

Let's start the experiment. General rule for all natural fabrics: the ashes should be ground into powder. The ashes of mixed fabrics cannot be ground into powder; lumps will still remain between your fingers.

How should wool behave?

The wool curls up into a ball and emits a burnt lint smell.

Result: I admit that wool was the most difficult for me. Since almost all wool was added, this slightly changed the reaction of the fabric to ignition. And, as you can see, the ashes were not ground into powder.

Cotton should burn like paper.