Types of fibers and introduction of their categories

Fibers are thin and long strands like hair that have enough strength and flexibility to produce yarn and fabric. Fibers are made of polymer materials. Polymer materials are very large molecules that are made by connecting smaller molecules called monomers. Therefore, a polymer is a large chain of identical molecules connected to each other. There are natural polymer materials suitable for fibers, but they can also be produced artificially. Cellulose is a natural polymer and polyester is a synthetic polymer.Knowing the properties of fibers is very important to carry out operations in the textile industry. One of these important characteristics of fibers is its length. The length of fibers is very important in choosing the type of spinning. For this reason, fibers are divided into two categories based on their length.
– Discontinuous fibers: Fibers such as cotton and wool that exist in the form of short strands and pieces are called discontinuous fibers. Because these fibers are natural, they are not all the same. The type of yarn production machines depends on the length of the fibers.
– Solid fibers: fibers that are long and reach hundreds of meters are called fibers or filaments. Silk is the only single natural fiber. Man-made fibers are made in the form of filaments, but by cutting and shortening, they become the desired length.

The fibers used in the textile industry can be generally divided into two categories: natural and man-made.
Natural fibers
Natural fibers exist in nature in the form of fibers and humans collect and use them. This category of fibers is divided into three groups: vegetable fibers, animal fibers and mineral fibers. Here we describe each of them briefly.

Plant fibers:

Plant fibers are one of the most important fibers used in the textile industry and are obtained from plants. The ingredient of this type of fiber is cellulose. Plant fibers are divided into the following categories according to which part of the plant they are obtained from
Seed fibers: These are fibers that grow on plant seeds, such as cotton fibers
Stem fibers: These fibers are obtained from the stems of plants, such as flax, hemp, and hemp fibers
Leaf fibers: These fibers are made from plant leaves, such as sisal and manila fibers
Fruit fibers: these fibers are extracted from the fruit of some plants. Like coconut fiber
Plant fibers are divided into two groups according to which part of the plant they grow in and how they are obtained. These two groups are: separate fibers and bundle fibers.

Separate fibers: they are fibers that grow in the form of fluff on the seed or fruit of the plant, such as coir, which is a grain fiber and coconut is a fruit fiber.
Bundle fibers: fibers that are found in bundles in the stem or leaves of some plants. The extraction of stem fibers is difficult because the stems of the plant must be soaked in water and then the fibers must be extracted from the inside of the stem with special devices. Flax, chetai, ramie, and hemp fibers are a group of fibers that are obtained from the stems of some plants. Sisal is a type of fiber made from plant leaves.

Cotton fibers

One of the most important plant fibers is cotton. Currently, the most important part of the textile industry is devoted to the weaving of cotton fabrics. The use of cotton as a fiber in textiles dates back to hundreds of years before Christ.Cotton fabrics were woven for the first time by the ancient Egyptians and the Chinese. Cotton cultivation is also common in Iran. And they are cultivated in Khorasan, Kerman, Fars and Central provinces. In recent years, cotton cultivation research centers have taken measures to improve cotton cultivation in Iran and have improved different breeds that are better in terms of quality, color and quantity. The production is better than the previous breeds. Cotton is grown in hot and humid areas and grows as a bush. Cotton fibers grow on small seeds called Cotton Seed. A number of cotton seeds grow inside the boll. After ripening and blooming, the cotton fibers come out of the boll. In this case, if it rains, it causes the cotton to turn yellow.Cotton harvesting is done manually and by machine. Manual harvesting has a slower speed, but less thorns and debris are collected along with the fibers.

After collection, these fibers are taken to the denim factory. In this step, the fiber is separated from the cotton seed. In order to be able to transport the fibers to the place of the spinning factory. Cotton fibers are packed by compressing and shrinking. This package is called a cotton bale.

Characteristics of cotton fibers

The side surface of cotton fibers is twisted and its cross section is similar to a bean seed. There is an empty channel in the middle of the cotton fibers that delivers nutrients and water to the fibers during growth. This channel is called lumen. The length of cotton fibers varies from 6 mm to about 25 mm. The longer the length of the fiber, the better the cotton.Currently, the best cotton is from Iceland, the length of these fibers varies between 83 and 25 mm. The thinner the fibers are, the finer they are, and the finer the cotton fibers are, the more valuable they are. Because finer fibers produce higher quality yarn and fabric. The color of cotton fibers varies from light brown to white, but the whiter the cotton fibers are, the better. Cotton fibers have very high moisture absorption and as a result they absorb body sweat well. On the other hand, due to high humidity absorption without us feeling it, they are always a little wet and as a result, they are cooler than other clothes in the summer. They do not cause sensitivity to human skin. They have high strength and their strength increases when wet.Cotton fibers wrinkle very quickly, so they are not suitable for formal clothes.
Cotton fiber has a good resistance against alkaline substances, so it can be resistant against caustic soda, but it has little resistance against acids, even if the acid concentration is low, it can damage the fibers. Cotton has good resistance to bleaching agents such as sodium hypochlorite and hydrogen peroxide, which is why these materials are used to bleach cotton fibers. Cotton fibers have a very good resistance to sunlight. Cotton fibers show high quality and even against heat, factors such as weather, soil, type of seed and breed of cotton fibers and choosing the right time depend. Fibers that have not matured well are weak and often leave the production line as waste.

Uses of cotton fibers

The use of cotton is very high, so that it is said that cotton is the most used fiber in the world. Cotton fibers are consumed in pure or mixed form. Adult clothes, children’s clothes, underwear and clothes that come in contact with the body, all kinds of towels, all kinds of sheets and covers for quilts and mattresses, all kinds of thick ropes, thread for sewing clothes, Zilo, baby diapers and all kinds of sterile bandages and Wound dressing cloths are cotton products.

Linen fibers

Flax fibers are taken from the stem of a one-year-old plant. This plant grows in areas with moderate climate. The more the secondary stems of the plant are higher than the main stem, the better the type of flax is. To prepare flax fibers, it must be harvested before the seeds of the plant reach. Harvesting time is very effective in fiber quality. If the crop is harvested early, the obtained fibers will be very fine and with low strength, but if harvested later, the fibers will be thick and fragile. After harvesting, the flax stalks are placed dry on top of each other so that air flows between them and they become whole.Then, through mechanical operations and hitting, the leaves and seeds of the plant are separated from its stems, then the stems are placed in stagnant or running water so that the stems get wet enough and the pectin substance that causes them to stick together The fibers have been destroyed. This action is called rating. After the stems are dried again, they are passed through steel rollers to break the stem and release its fibers. Figure 6 shows linen fibers and thread. The transverse section of the plant stem consists of four parts.
A) The outer shell, which is thick and protects the fibers and the plant.
b) The set of fibers that is under the main shell.
c) The wood area that makes the stem strong.
t) The core of the stem, which is soft and cork-shaped.

If we look at the cross-section of linen fibers under a microscope, we can see irregular hexagonal shapes with a channel in the middle. This channel is like cotton fibers for feeding the fibers. Flax fibers are different depending on which part of the plant they are placed in. The length of the flax fibers varies from 40 to 60 cm. The color of the flax fibers is related to the way the fibers are processed in the retting stage and is white, yellow, green. And brown is seen, the better the retting process is done, its color is twice that of cotton fibers and its strength increases when it gets wet. The strength of linen fibers is almost twice that of cotton fibers.But these fibers are rougher and harsher than cotton. The surface of linen fibers contains a waxy substance that makes it more shiny than cotton. This substance is lost due to bleaching and washing a lot. Like cotton, linen fibers tolerate heat well and are insulating, and although they tolerate sunlight well, their strength decreases in the long term.

Chatay fibers

Chetai fibers are obtained from the stem of a one-year-old crocus plant, and because it is a stem fiber, its preparation method is similar to linen. The fibers have a hard and rough appearance. Chettai fibers are abundant and cheap, and are relatively used for preparing rice sacks and bags of barley and wheat.Other uses of these fibers are covering the back of flooring and all kinds of ropes and tar cloth and sacks.

ramie fibers

Rami fibers are also obtained from the stem of a plant and it is known as Chinese grass. Its fibers are separated from the stem like flax by retting. But in the rating stage, warm water, detergents and caustic soda should be used in the solution so that the fibers can be separated from the stems more easily. Rami fibers are white and shiny, their strength is good, and they absorb water easily, and as a result, they are easily dyed. Rombli, curtains and clothes are also used.

hemp fibers

This fiber is very similar to Chetai, and the way it is prepared is similar to Chetai. The color of this fiber is from light yellow to thick, and it can be used to make sacks or milky. Its surface is dry and rough. These fibers are used as ropes.

Sisal fibers

Sisal fibers are obtained from the leaves of a plant. The sisal plant is 7 years old and the length of its fibers reaches about one meter. This fiber is fragile and thick and has a white to milky color. Its most use is making motion transmission belts because it has very high strength. Fabric cannot be made from these fibers.

Animal fibers

These fibers are of animal origin. There are two types of animal fibers, hair fibers and silk fibers. Hair fibers are prepared by separating the hair grown on the skin of some animals. Among the hair fibers are sheep’s wool and camel hair, goat hair and rabbit hair. Among hair fibers, wool has the highest consumption. Silk is an animal fiber that has a protein origin and is produced by silkworms. Wool fibers Centuries before Christ, Egyptians, Babylonians and Greeks spun wool by hand and made beautiful fabrics with it. In the first centuries AD, the best woolen fabrics were woven in Baghdad and Damascus, as well as in Turkey.In the Middle Ages, the wool industry reached its peak in Italian cities such as Venice and Florence, and then spread to other European countries such as Belgium, Holland and England. However, since herding for the purpose of meat production is prevalent in most parts of the world, it can be said that most of the countries in the world are wool producers. In some countries, such as Australia, New Zealand and South Africa, more attention is paid to animal wool than meat. Therefore, these countries are among the first-class exporters of wool in the world. Therefore, one of the oldest and most important textile fibers is wool. Wool is a group of animal fibers. This type of fiber is obtained from different animals, but the most important of them is sheep’s wool.The component of these fibers is a type of protein. Sheep wool is the most widely used animal fiber and is made from different breeds of sheep. Camel wool and goat and rabbit hair are also used in the textile industry to a limited extent. The growth of wool fibers starts from hair follicles under the skin of the animal. Then it comes out of the pores on the skin and grows. Wool fibers do not grow directly, but rather twist and twist. This twist is one of the most important characteristics of wool fibers that makes wool unique. Usually, every year after winter, wool fibers are harvested. Special electric tools have also been made for picking wool.Breed is the most important factor in wool breeding. Because the wool of each type of sheep has a different quality. The best wool comes from Merino sheep. Also, warm weather is more suitable for growing fine fibers, in addition to that, the land where sheep are raised and the type of feed and fodder consumed affects the quality of wool. After picking the wool fibers, they place it on a table, separate the different parts of the sheep’s wool and put them in separate containers. This work is called sorting. In general, the value of graded fibers is higher than the fibers that are not graded.

Properties of wool fibers

Wool fibers have high moisture absorption and absorb moisture up to 25% of their weight. These fibers have warm properties and are very suitable in winter. The strength of wool fibers is not very good and when wet they lose 2% of their strength. Woolen fibers have a very low resistance to alkali, but their resistance to acids is good. Wool is vulnerable to sodium hypochlorite (Vitex) and for this reason hydrogen peroxide or similar substances are used to whiten wool. Washing woolen clothes is done with water at about 53 degrees Celsius and with the least mechanical actions because hot water along with stretching changes the dimensions of woolen clothes. The stability of wool against heat and sunlight is much less than cotton.

Silk

Silk entered Iran about 38,000 years ago, while it was popular in China 6,000 years before that. Silk is also a group of animal fibers and has a protein structure. Silk has 75% protein called fibroin and 23% sericin gum, and the rest of its ingredients are fat, wax and minerals. Silk fibers are produced by silkworms. After it matures, the silkworm turns into a butterfly and tears the cocoon around itself and emerges as a butterfly. The food of the silkworm is the leaves of the mulberry tree.

Life stages of the silkworm The silkworm feeds on the leaves of the mulberry tree or a type of oak. After the silkworm has grown enough, it begins to spin the cocoon. To make a cocoon, a slimy liquid is secreted from two glands near the mouth of this worm, which hardens in the vicinity of air. The worm stays in the cocoon during the day. After this period, it turns into a butterfly for 20 days and comes out of the cocoon. The butterfly has to pierce the cocoon to get out. Because the value of a punctured silk cocoon is much lower than that of a healthy cocoon, to prevent the cocoon from being punctured, it should be placed at 8°C to 0 after the cocoon is complete, at the temperature of the propeller, or it is destroyed by steam. . The weight of each cocoon is from 1 to 4 grams.

Silk fibers are variable. The only natural fiber is single or 400 to 1200 meters long. There are also wild silkworms, but their fibers are short due to the perforation of their cocoons. As a result, their fibers are used as short fibers.
To make thread from healthy cocoons, they are placed in a container of boiling water and a little soap, and then they find the head of each cocoon and turn it into a silk filament thread. Silk has a smooth surface and does not have high resistance to heat and sunlight. Silk fibers are used in decorative products and expensive fabrics and the texture of exquisite carpets due to their high luster.

Mineral fibers: Fireproof cotton is the only natural mineral fiber and it is made of aluminum and magnesium silicates. Its other name is asbestos. To produce asbestos, first of all, fireproof cotton veins are identified in the rocks, and they get it long and white. . These fibers, and then through the crushing of mineral stones, fibers have relatively many industrial uses and are also used in fireproof fabrics, considering that these fibers have been proven to be carcinogenic, working with these materials requires great precision and Compliance with safety precautions.

Manmade Fiber

Man-made fibers are fibers that do not exist in nature and are made by humans in factories. These fibers are divided into two distinct subgroups, i.e. recycled fibers and synthetic fibers, according to the material required to make them. It should be converted into fibers. Threading or turning pulp materials into fibers is done in a way that is related to the type of fiber pulp material. When the polymerization material is prepared, it should be converted into fibers. This process is called threading. In general, there are three methods for this work.Melt spinning method In this method, the main material is heated until it melts completely, and after several stages of smoothing under pressure, it is passed through very small holes so that it becomes thin strands. After this stage, the fibers are stretched. To increase its strength, Christian’s dry method. In this method, the fiber material is dissolved in a solvent and the supervisor prepares it by smoothing. and become fibers, these fibers usually do not have a round cross-section, triacetate fibers are of this type.Tracey method In this method, materials suitable for fibers are mixed with a special material. In this case, if acid reaches this material, it immediately hardens and so-called coagulates. then the materials are removed from the filament maker, as soon as these materials are removed, they combine with acid and produce fibers. The coagulation operation is very important because many of the good properties of the desired fibers are obtained through proper coagulation of acetate and viscose fibers. They are of this example. and viscose are examples of this.

Regenerated Fiber
The primary material of loosely woven fibers exists in the form of polymer in nature, and by making changes in this polymer, humans give these materials the ability to dissolve in a suitable solvent and then be spun. Viscose, diacetate, triacetate and casein are among these fibers.

Viscose rayon

Viscose is an open fiber because the primary material, which is cellulose, is taken from nature. Viscose is a fiber, cellulose fiber, and therefore has the properties of cellulose fibers. To prepare this fiber, the raw materials must first be converted into smaller parts. In order to produce fibers, it is necessary to chain the cellulose molecules so that the material chains are made into a paste and passed through very small openings to form fibers.Finally, after a lot of research, the materials and technology needed for this work were obtained and viscose fibers were produced. But this fiber had little strength, and especially when it absorbed moisture, it became less strong, but with extensive research, the amount of polymer chain shortening reached the right size. Currently, viscose fibers are produced with good quality. Viscose fibers are made from these materials. They have a percentage of cellulose.
– Short cotton fibers (linters) of these materials have 99% cellulose.
– The wood of trees such as fir, pine, cypress and other trees were suitable. These trees have between 84 and 94% cellulose. Sugarcane pomace that has 50% cellulose.
-Rice straw, wheat straw and barley

Viscose fibers are very shiny, but their strength is low, especially in the wet state, which has less strength. Fabrics made of viscose fibers can be used as curtains, bedspreads, covers for train and bus seats, tablecloths and all kinds of women’s clothes, men’s shirts, underwear and sportswear. These fibers can be mixed with other fibers. If we mix viscose with polyester, the strength of the product increases, for example, because polyester is strong and compensates for the weakness of viscose.

Polynosic fibers

Polynosic fiber is also considered a cellulosic fiber and was the result of research to increase the strength of cellulose. This fiber has much better properties than viscose. The higher strength of this fiber in dry and wet state has made this fiber to be called reinforced viscose. These fibers are used in knitted fabrics such as blouses, jackets, sofa covers and curtains.

Copper ammonium fibers

These fibers are cellulose fibers and look very similar to silk, and for this reason, these fibers are also called artificial silk. These fibers are very soft and it is possible to produce fine fibers from them. The production of these fibers, like viscose, starts with cellulosic raw materials. But short fibers (linters) have a more important place. Because there is more cellulose in these materials. These fibers are used in sports clothes, curtain fabrics, tablecloths and rugs.

Acetate fibers

Continued research on cellulose fibers led to a completely different method for fiber production.In this method, cellulose materials are reacted with acetic anhydride. In this case, there are changes in the cellulose chain and the raw material of acetate fibers is created. Then, by passing the material through very fine holes, the desired fibers are obtained. Acetate fibers are made as diacetate and triacetate. The properties of diacetate fibers are somewhat similar to cellulose fibers, but triacetate fibers are not similar to cellulose fibers. Triacetate is brilliant. It has good strength, absorbs little moisture, has a high melting point and does not wrinkle easily. Triacetate fibers do not absorb natural colors, and as a result, they are resistant to staining and are easy to clean. Because of this, they are very suitable for roomy fabrics, curtains and flooring.

Casein fibers

Casein is one of the recycled fibers, which is a protein and is obtained from milk. To prepare casein, skimmed milk is first precipitated with the help of acetic anhydride, and after performing additional actions and creating a suitable paste, they are rejected from the string maker. to become fibers. These fibers have properties similar to wool. But it is weaker than wool. Casein fibers are cheaper than wool and mixed with wool are also used. The mixture of these two is used in machine carpet weaving.

Glass fibers

Glass fiber is one of the recycled mineral fibers. This fiber, which is known as fiberglass, is obtained from a mixture of silicate rock, limestone, sodium carbonate and borax. After heating, melting, and stringing, thin and fragile fiberglass fibers are produced. Glass wool is another name for these fibers. These fibers are used for building insulation and steam transmission pipes.

Synthetic fibers

These fibers are made from materials found in nature such as some gases and some chemicals that are often of petroleum origin.The primary wad of synthetic fibers does not exist in the form of fiber and has no plant or animal origin. First, they choose a raw material that has the ability to join together and polymerize, as mentioned before, this material is called a monomer, and with the help of polymerization, thousands of monomers are connected in the form of chain beads and in order. become If the number of chain molecules reaches the appropriate level, this material will have the ability to be spun and become fibers in the string maker. Many fibers are made in this way, but not all of them are used in the textile industry. The most widely used synthetic fibers in the textile industry are nylon fibers, polyester fibers, and acrylic fibers.

Polyester fibers

Polyester fibers are prepared from the combination of two substances called ethylene glycol and terephthalic acid under favorable conditions and in the vicinity of a suitable catalyst in a vacuum. This material comes in the form of plastic pieces and after cutting and shredding it becomes called chips, after that these materials are melted at 280 degrees Celsius and then polyester fibers are prepared with the help of melting spinning method. to be.In order for the polyester fibers to find a suitable state and sufficient strength, they are passed through tension rollers. Polyester fibers are shiny, but the amount of shine can be controlled during production. Polyester fibers absorb little moisture and have high strength. Polyester fibers are very strong even when wet. These fibers are resistant to chemicals. but they tend to absorb particles and dust and as a result they get dirty quickly. These fibers dry quickly and for this reason they are known as wash and wear fibers. Thin, strong and light fabrics, curtain fabrics and fabrics suitable for ordinary umbrellas and parachutes are also used in polyester.

Nylon fibers

After much research, nylon fibers were made from the polymerization of two substances called adipic acid and hexamethylenediamine. Later, with changes in the raw materials and the type of operation, nylons with different properties are made of nylon garbage bags and the plastic materials used in many plastic kitchen utensils are made of nylon. The names of some of these fibers are: Nylon 66, Nylon 11. Nylon fibers are made by melt spinning method and it needs stretching operation to convert the production thread into fibers. It has good strength, but it does not have good heat resistance.Therefore, you should be very careful when ironing, because if the temperature of the iron is about 180 degrees Celsius, it will melt a little and stick to the ironing devices. Usually, necessary settings and warnings are installed on the ironing devices. Nylon fabrics are easily washed and quick drying is one of the characteristics of nylon. When it burns, it first melts and the contact of its molten material with the body produces blisters. Nylon creates static electricity and therefore, if you are wearing nylon clothes, you will feel electrocuted if you touch anything. This property also becomes a problem during spinning.

The uses of nylon fibers are sports clothes, socks, car airbags, threads around car tires and even airplane tires, all kinds of belts, fishing equipment and ropes and wefts of car carpets. Acrylic fibers, these fibers are made from a material called acrylonitrile. Acrylonitrile monomers are connected through chemical bonds. After this molecule becomes big enough, it becomes a suitable material for fiber production. After washing, these materials are passed through a strainer and dried. Acrylic fiber polymer is dissolved in a solvent called dimethylformamide and these fibers are produced by dry spinning method.Although this fiber is not similar to wool in terms of structure, it is heat insulating in terms of properties like wool fibers, and therefore it is also known as synthetic wool. In general, being warm and soft is one of the main characteristics of acrylic fibers, and one of the uses of these fibers is winter clothes, thick knitwear, and carpet weft. Like nylon and polyester, acrylic fibers can be made in both filament and cut forms. Acrylic fibers are also made with the help of bulky methods, which makes the produced yarn softer and the product produced from this yarn is warmer. Factories producing acrylic fibers put their own names on these fibers. Erlon, Cortel, Akrilan, Krislan, Zafaran are some of these products.

Mixed fibers

By studying the fibers, we saw that their properties are different. It is not a good feature, for example, cotton wrinkle quickly, which is not a good feature, but instead it has a comfortable cover. Therefore, the purpose of mixing fibers is to obtain good and appropriate properties in the fabric obtained from the mixture. The amount of each fiber in the mixture is determined by the following factors.
– Obtain the desired property in the mixture.
– According to the price of different fibers, the price obtained should be appropriate.
In terms of spinning technology, it is possible to mix them.
– There is a possibility of dyeing, printing and finishing for the mixture.