Rayon and Flush: It is the name given to regenerated cellulose fiber in filament form. It is the most important representative of natural origin man-made fiber production. Since there are very few companies producing rayon in our country, it is generally imported and used.
Cellulose-based regenerated fiber types are:
HWM (High Wet Modulus Rayon),
kızıpine, Kayın, cellulose ratio such as spruce, popları the high ağtake advantage of the hungryıcellulose obtained by chemicalşnot subject toıIt is a staple fiber type produced artificially with
In viscose production,ğthey are hungry; shell kısıDo you haveı çısnowıldıafter talaş adı break it up into small pieces givenılmtadır.Tala n, high sıtemperatureıct and bassıAs a result of treatment with chemicals such as NaOH (Sodium hydroxide) or Ca(HS03)2 (Calcium hydrogen sulfide)ıcellulose dheatfound in diğremove all substances (such as lignin, hemicellulose, pectin)ştırılması sağplannedır. The pure cellulose obtained is melted in a 17,5%-18% NaOH solution at 18–20°C and a homogeneous snow is formed.heatbe mı split into smaller pieces forılmtadır. Then with CS2 (carbon sulfide)şAfter seeing the viscous namegiven in orange and dark reda solution is obtained. This solution is eitherIt is converted into filament by spinning (spinning) method, the resulting filament is called viscose silk. are given.
Viscose fiber is also used by mixing with other fiber types such as cotton, linen and wool.It is produced from eucalyptus, willow and poplar wood. It consists of cellulose like cotton. There is almost no chemical change in the structure of cellulose, which becomes fluid during the viscose production process. Its feature is higher than that of cotton. It is very suitable for dyeing and printing due to this moisture absorption feature, which is much higher than cotton. It makes colors appear brighter. Dry durability is lower than cotton. Its elongation is 15-30%, twice as high as cotton.
Yaş production of viscose by drawing method
viscose fiberı usually two şis obtained in the crop.
>>> Viscose rayon (in filament form)
>>> viscose (Şin tape)
Obtained from wood and linter for the production of viscose. cellulose raw material caustic soda and sodium bisulfiteşforeign by seeingı free of substancesındırılır.
cellulose pulp with caustic soda solution (NaOH)şby seeing alkali cellulose get back to beingşproduct
to alkali cellulose, pre matureştıRMA işby adding carbon sulfide (CS2) after the cellulose xanthate obtained.
With the addition of dilute sodium hydroxide raw viscose back to solutionşis formed.
Filtering and mature backştıRMA işafter the realm viscous solution from the nozzles to an acidic bath fbusinesskırtıas, orş floor by shooting methodı viscose filaments are obtained.
Catılaşmoment filaments, stretching yıwedge and dryerşwind it on the bobbinıto viscose rayon yarn obtained.
filaments tow (cable) şare brought together. cutting işalso with lem şbecome taperedşis formed. Yıwedge and dryerşbale after lemmingsır and viscose fiberı obtained in bales işshipped to businesses.
Viscose, staple regenerated cellulose fiberıSee r and general featuresımıcotton fromğIt resembles a.
Physical Structure and Properties of Viscose Rayon Fiber
Microscopic view: There are lines running along the fiber. Its cross section is indented.
Length: It is generally in filament form. Viscose fiber is obtained by cutting it to the desired length according to the place of use.
Fineness: 50-900 denier fine yarn can be produced. Monofilament fineness is 1-1,5 denier.
Color: If it is not specially mattified, it is transparent when produced.
Brightness: They are shiny when produced.
Strength (dry): Dry strength is good in viscose rayon and excellent in modal. Strength in viscose rayon is around 2-3 gr/denier.
Strength (age): There is a 30-50% decrease in strength when wet.
Elongation Strength: Viscose fibers; dry % They grow by 10-11, 25-35% in age.
Resilience (spread): The viscose rayon has low modal resilience. The handle characteristics of the modal are similar to high-quality cotton.
Dehumidification: It is more hydrophilic than natural cellulosic fibers with a moisture uptake of 10-16%. Since they absorb more water, they dry more slowly. Their slow drying is also due to the fact that they absorb moisture quickly.
Temperature: They are affected by sunlight and lose their strength. They lose power above 150 °C. The ironing temperature is around 135 °C.
Flammability: They burn easily and quickly.
Static Electricity: They don't have too many static electricity problems.
Pilling: It does not have pilling problems because it is mostly used in filaments.
Intensity: With a density of 1,50 g/cm³, it is lower than cotton, polyesterhas a higher density than
Usage Features: It does not have thermoplastic properties. Viscose rayon is a good conductor. In terms of general properties of viscose rayon, Although it is similar to cotton, its reaction against various effects applied in fiber production, dyeing and printing, and finishing processes is different. Cotton Although its main structure is 100% cellulose, since the degree of polymerization is lower; It is weaker than cotton and has less resistance to chemicals.
Chemical Properties of Viscose Rayon Fiber
Acids: It is affected by strong acids. Hot diluted mineral acids or cold concentrated acids degrade the fiber.
Bases (alkalis): Their resistance to bases is lower than cotton. Strong bases reduce its durability.
Organic Solvents: Dry cleanable. It is resistant to dry cleaning agents.
Bleaching items: The effect of oxidizing and reducing substances is the same as in cotton. It is affected by bleaches such as sodium hypochlorite (NaCIO).
Mold and fungus: When clean and dry, it is resistant to mold and fungus growth. Their strength depends on humidity and temperature. In the appropriate environment, mold and fungi cause discoloration.
Moths, insects: It is moth resistant. Some insects can cause indirect damage.
Light, atmospheric conditions: It will be damaged if it stays in the sunlight for a long time.
Water: It will swell. Its strength decreases when wet.
Painting: Its affinity for dyestuffs is higher than cotton material. DirectlyIt can be dyed with cube and sulfur dyestuffs.
Since it resembles natural silk, it is used instead of natural silk in places that do not require durability. Dress, shirt, nightgown, jacket, curtain and upholstery fabric, medical product, non woven fabric production, home textile products, etc. used in the fields.
VISCOSE RAYON FIBER AND FABRIC PROPERTIES
Rayon is the general name given to regenerated cellulosic fibers. Among all fibers, rayon continues to be the fiber that most confuses and attracts consumers, as it can be used in a wide variety of fields and has the characteristics of both natural fibers and synthetic fibers. Rayon can be used as a substitute for cotton fiber in many places, and it is used in the clothing industry, home textiles and industry in a wide range from absorbent hygiene products to baby pads and high-strength cord fabrics.
Rayon is the first fiber ever produced. It was developed in France during a research covering the general properties of cellulose in the 1890s and was called "artificial silk" (artificial silk) in those years because it resembles silk.. In 1924, this fiber was given the name "rayon" meaning "rays of light" by the textile industry. The most important feature is that it is not synthetic like other man-made fibers. It is produced from cellulosic-based cotton linters or wood pulp obtained from spruce wood. As a result of this, The properties of rayon fiber resemble natural cellulosic fibers such as cotton and linen rather than synthetic fibers such as nylon and polyester. The wide variety of uses of rayon as a fiber, its lower cost compared to cotton and its superior comfort properties have made its usage area quite widespread.
Classification of rayon
Due to the structure of rayon fiber, it has the characteristics of natural and synthetic fibers, making it a widely used fiber recently. Rayon can be used as a mixture with finely drawn synthetic filaments, as well as in the form of staple fiber, which is folded and cut into 6 - 20 cm lengths.
When evaluated in terms of product performance, rayon can be classified under four headings. Among them, normal rayon (viscose) and high strength rayon constitute two important groups.
1. Normal rayon (viscose): Viscose to cut rayon fibers used in mixture with staple fibers (cotton, wool) is named. It is the rayon type with the highest market share. It is used in ready-made clothing and home textiles and is referred to as "viscose" in the washing instructions. Its distinguishing feature is its very low wet strength. As a result, it becomes unstable and shrinks or releases when wet. Dry cleaning or very delicate hand washing is generally recommended to preserve the appearance and functional properties of fabrics made from this fiber. Untreated rayon can shrink by 10% when washing in the washing machine.
2. High wet strength (polynosic) rayon (high wet modulus rayon)): Various researches have been made to improve the above-mentioned negative properties of rayon fiber and rayon fiber has been modified by different processes. These are called high strength viscose rayons and because of their high durability, especially when wet. high wet modulus abbreviated form of HWM are symbolized by HWM rayon In addition to its high wet strength, it has other properties of viscose. It can be washed in washing machines, dried in dryers and can perform as well as cotton products during these processes. In order to increase its brightness, it can be subjected to mercerization process like cotton. In the clothing industry, it is called polynosic rayon or modal with its trade name. It differs from viscose in the degree of polymerization, degree of crystallization, size of the crystalline regions, degree of orientation and uniformity in the filament. For this reason, the durability, breaking strength, flexibility and friction resistance of the fabrics produced from these fibers are higher than the normal rayon fiber. Its strength is 3,0 – 4.0 g/denier when dry and 1.9 – 2.5 g/denier when wet. It does not swell as much as viscose fiber with water.
3. High tenacity rayon: It is a modified form of viscose, twice the strength of HWM rayon. It is used in cord fabrics and in the industrial field.
4. Cupramonium rayon: Although it is similar to other rayons in terms of properties, it has not been produced recently because environmentally harmful substances are used during its production.
Characteristics of viscose fiber
Viscose fiber can be obtained in different finenesses depending on the nozzle used during production. Its cross-section is not circular, but curved. Since viscose fiber is a regenerated cellulosic fiber, it has many properties of cotton.
Compared to viscose cotton, although both are 100% cellulose, they have many different properties due to their different degrees of polymerization.
The degree of polymerization is between 2000 – 10000 in cotton and 200 – 250 in viscose.
The proportion of crystalline regions is 70% in cotton and 40% in viscose.
These differences in chemical structure create differences in the mechanical, comfort and aesthetic properties of viscose.
Viscose fiber is weaker than cotton and less resistant to chemical reagents. On the other hand, due to its absorbent feature, the textiles produced from this fiber have a very comfortable, skin-compatible, breathable, soft and draped structure.
Positive and negative properties of viscose fiber:
• Strength: The most striking feature of viscose fiber is that its strength drops a lot when wet.
Strength dry 2.0 – 2.6 g/denier; It is 0.95 – 1.5 g/denier in wet condition.
It can elongate at a rate of 17-25% without breaking.
• Absorbency: Another important feature of viscose is that it is the most absorbent of all cellulosic fibers.
It absorbs sweat very well, so it is preferred in summer clothes.
It can be easily dyed thanks to its absorbency feature.
It swells more than cotton in water and basic solutions.
At 60% relative humidity, it absorbs 11-13% moisture.
• Use: The most obvious problem in viscose from the user's point of view is that its wet strength is low and its dimensional stability is very low due to the fact that it absorbs too much moisture.
It is shorter in length and width than similar cotton fabrics.
It releases when hang-drying.
In knitted viscose fabrics, the problem of turning may occur.
During frequent use, pilling problem may occur.
Since it is not flexible like other cellulosic fibers, it has poor abrasion resistance and can be easily damaged.
It is less resistant to heat during ironing than cotton.
Durability decreases at temperatures above 150ºC.
It burns at temperatures of 185 – 205ºC.
• Appearance: Viscose fiber has a smooth surface and is very shiny. Because of this feature, it can be used instead of silk in places where durability is not important.
Viscose has become popular due to its high variety as a result of using it in a mixture with other fibers. It is mixed with fibers such as cotton, wool, silk, acrylic and lycra to reduce cost, increase comfort and increase brightness.
While viscose has some of the properties of cotton and polyester, it has superior properties to both fibers in many respects.
Although the comfort and aesthetic properties of viscose fiber are good, its “washability” feature is poor.
The fact that viscose, as an artificial fiber, has superior aesthetic properties and comfort properties of natural fibers, and its low cost have enabled it to appear in all types of products in daily life. Viscose is used in ready-made clothing, home textiles and industrial areas, alone or in a mixture. Places of use are related to comfort and aesthetics rather than durability.
Usage areas of viscose fiber
• Clothes: Dresses, blouses, jackets, pants, underwear, t-shirts, sports shirts, sportswear, suits, ties, work clothes, hats, accessories.
• Home textiles: Bedspread, blanket, curtain, sheet, tablecloth, upholstery fabric.
• Industrial use: Industrial products, medical surgical products, nonwoven materials, cord fabrics.
• Other: Feminine hygiene products, diapers.
More specifically, it is used in the following products as a mixture with different fibers:
• Viscose – cotton blend: Towel, bed linen, handkerchief, knitted clothes, denim, dress.
• Viscose – wool blend: Fine woolen clothes, sweater.
• Viscose – silk blend: Slim fancy dress.
• Viscose – acrylic mixture: Knitted clothes, towels, bed linen, furnishings.
• Viscose – lycra mixture: Underwear, stretch top knit wear, swimwear, sportswear.