
[Perhaps from French rayon, ray of light (from its sheen), from rai, from Old French. See ray1.]
A textile made from cellulose. There are two types, both made from wood pulp. In the viscose process, the pulp is dissolved in carbon disulphide and sodium hydroxide to give a thick brown liquid containing cellulose xanthate. The liquid is then forced through fine nozzles into acid, where the xanthate is decomposed and a cellulose filament is produced. The product is viscose rayon. In the acetate process cellulose acetate is made and dissolved in a solvent. The solution is forced through nozzles into air, where the solvent quickly evaporates leaving a filament of acetate rayon.
Background
For centuries humankind has relied upon various plants and animals to provide the raw materials for fabrics and clothing. Silkworms, sheep, beaver, buffalo deer, and even palm leaves are just some of the natural resources that have been used to meet these needs. However, in the last century scientists have turned to chemistry and technology to create and enhance many of the fabrics we now take for granted.
There are two main categories of man-made fibers: those that are made from natural products (cellulosic fibers) and those that are synthesized solely from chemical compounds (noncellulosic polymer fibers). Rayon is a natural-based material that is made from the cellulose of wood pulp or cotton. This natural base gives it many of the characteristics—low cost, diversity, and comfort—that have led to its popularity and success. Today, rayon is considered to be one of the most versatile and economical man-made fibers available. It has been called "the laboratory's first gift to the loom."
In the 1860s the French silk industry was being threatened by a disease affecting the silkworm. Louis Pasteur and Count Hilaire de Chardonnet were studying this problem with the hope of saving this vital industry. During this crisis, Chardonnet became interested in finding a way to produce artificial silk. In 1885 he patented the first successful process to make a useable fiber from cellulose. Even though other scientists have subsequently developed more cost-effective ways of making artificial silk, Chardonnet is still considered to be the father of rayon.
For the next forty years this material was called artificial or imitation silk. By 1925 it had developed into an industry unto itself and was given the name rayon by the Federal Trade Commission (FTC). The term rayon at this time included any man-made fiber made from cellulose. In 1952, however, the FTC divided rayons into two categories: those fibers consisting of pure cellulose (rayon) and those consisting of a cellulose compound (acetate).
By the 1950s, most of the rayon produced was being used in industrial and home furnishing products rather than in apparel, because regular rayon (also called viscose rayon) fibers were too weak compared to other fibers to be used in apparel. Then, in 1955, manufacturers began to produce a new type of rayon—high-wet-modulus (HWM) rayon—which was somewhat stronger and which could be used successfully in sheets, towels, and apparel. The advent of HWM rayon (also called modified rayon) is considered the most important development in rayon production since its invention in the 1880s.
Today rayon is one of the most widely used fabrics in our society. It is made in countries around the world. It can be blended with natural or man-made fabrics, treated with enhancements, and even engineered to perform a variety of functions.
Raw Materials
Regardless of the design or manufacturing process, the basic raw material for making rayon is cellulose. The major sources for natural cellulose are wood pulp—usually from pine, spruce, or hemlock trees—and cotton linters. Cotton linters are residue fibers which cling to cotton seed after the ginning process.
Strictly defined, rayon is a manufactured fiber composed of regenerated cellulose. The legal definition also includes manufactured fibers in which substitutes have not replaced more than 15 percent of the hydrogens.
While the basic manufacturing process for all rayon is similar, this fabric can be engineered to perform a wide range of functions. Various factors in the manufacturing process can be altered to produce an array of designs. Differences in the raw material, the processing chemicals, fiber diameter, post treatments and blend ratios can be manipulated to produce a fiber that is customized for a specific application.
Regular or viscose rayon is the most prevalent, versatile and successful type of rayon. It can be blended with man-made or natural fibers and made into fabrics of varying weight and texture. It is also highly absorbent, economical and comfortable to wear.
Regular viscose rayon does have some disadvantages. It's not as strong as many of the newer fabrics, nor is it as strong as natural cotton or flax. This inherent weakness is exacerbated when it becomes wet or overexposed to light. Also, regular rayon has a tendency to shrink when washed. Mildew, acid and high temperatures such as ironing can also result in damage. Fortunately, these disadvantages can be countered by chemical treatments and the blending of rayon with other fibers of offsetting characteristics.
High-wet-modulus rayon is a stronger fiber than regular rayon, and in fact is more similar in performance to cotton than to regular rayon. It has better elastic recovery than regular rayon, and fabrics containing it are easier to care for—they can be machine-washed, whereas fabrics containing regular rayon generally have to be dry-cleaned.
The Manufacturing
Process
While there are many variations in the manufacturing process that exploit the versatility of the fiber, the following is a description of the procedure that is used in making regular or viscose rayon.
Regardless of whether wood pulp or cotton linters are used, the basic raw material for making rayon must be processed in order to extract and purify the cellulose. The resulting sheets of white, purified cellulose are then treated to form regenerated cellulose filaments. In turn, these filaments are spun into yarns and eventually made into the desired fabric.
Processing purified cellulose
Producing filaments
Spinning
Spool Spinning is very similar to Pot Spinning. The filaments are passed through rollers and wound on spools, where they are washed, bleached, rinsed, dried, and wound again on spools or cones.
In Continuous Spinning, the filaments are washed, bleached, dried, twisted, and wound at the same time that they are stretched over godet wheels.
High-Wet-Modulus Rayon
Manufacture
The process for manufacturing high-wet-modulus rayon is similar to that used for making regular rayon, with a few exceptions. First, in step #1 above, when the purified cellulose sheets are bathed in a caustic soda solution, a weaker caustic soda is used when making HWM rayon. Second, neither the alkali crumbs (#1 above) nor the viscose solution (step #2) is aged in the HWM process. Third, when making HWM rayon, the filaments are stretched to a greater degree than when making regular rayon.
Quality Control
As with most chemically oriented processes, quality control is crucial to the successful manufacture of rayon. Chemical make-up, timing and temperature are essential factors that must be monitored and controlled in order to produce the desired result.
The percentages of the various fibers used in a blended fabric must be controlled to stay within in the legal bounds of the Textile Fiber Identification Act. This act legally defines seventeen groups of man-made fibers. Six of these seventeen groups are made from natural material. They include rayon, acetate, glass fiber, metallics, rubber, and azion. The remaining eleven fabrics are synthesized solely from chemical compounds. They are nylon, polyester, acrylic, modacrylic, olefin, spandex, anidex, saran, vinal, vinyon, and nytril.
Within each generic group there are brand names for fibers which are produced by different manufacturers. Private companies often seek patents on unique features and, as could be expected, attempt to maintain legal control over their competition.
Byproducts
As one of the industry's major problems, the chemical by-products of rayon have received much attention in these environmentally conscious times. The most popular method of production, the viscose method, generates undesirable water and air emissions. Of particular concern is the emission of zinc and hydrogen sulfide.
At present, producers are trying a number of techniques to reduce pollution. Some of the techniques being used are the recovery of zinc by ion-exchange, crystallization, and the use of a more purified cellulose. Also, the use of absorption and chemical scrubbing is proving to be helpful in reducing undesirable emissions of gas.
The Future
The future of rayon is bright. Not only is there a growing demand for rayon worldwide, but there are many new technologies that promise to make rayon even better and cheaper.
For a while in the 1970s there was a trend in the clothing industry toward purely synthetic materials like polyester. However, since purely synthetic material does not "breath" like natural material, these products were not well received by the consumer. Today there is a strong trend toward blended fabrics. Blends offer the best of both worlds.
With the present body of knowledge about the structure and chemical reactivity of cellulose, some scientist believe it may soon be possible to produce the cellulose molecule directly from sunlight, water and carbon dioxide. If this technique proves to be cost effective, such hydroponic factories could represent a giant step forward in the quest to provide the raw materials necessary to meet the world wide demand for man-made fabric.
Where To Learn More
Books
Corbman, Bernard P. Textiles: Fiber to Fabric, 6th ed. McGraw-Hill, 1983.
Hollen, Norma, Jane Saddler, Anna Langford, and Sara Kadolph. Textiles, 6th ed. Macmillan, 1988.
Periodicals
Foley, Theresa M. "Rayon Fiber Manufacturer Shuts Down, Threatening U.S. Booster Production." Aviation Week & Space Technology. November 7, 1988, p. 29.
Smith, Emily T. "A Safe Shortcut around the Toxic Road to Rayon." Business Week. February 11, 1991, p. 80.
Templeton, Fleur. "From Log to Lingerie in a Few Easy Steps." Business Week. April 6, 1992, p. 95.
"Turning Corn and Paper into Rayon." USA Today. June, 1991, p. 7.
[Article by: Dan Pepper]
Continuous-filament yarn composed of regenerated cellulose; similar in chemical structure to natural cellulose fiber but contains shorter polymer units; usually made by the viscose process.
Rayon is a popular fabric used for making shirts, skirts and dresses.
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Rayon is a manufactured regenerated cellulose fiber. Because it is produced from naturally occurring polymers, it is neither a truly synthetic fiber nor a natural fiber; it is a semi-synthetic[1] or artificial[2] fiber. Rayon is known by the names viscose rayon and art silk in the textile industry. It usually has a high luster quality giving it a bright sheen.
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Some major rayon fiber uses include apparel (e.g. Aloha shirts, blouses, dresses, jackets, lingerie, linings, scarves, suits, neckties, hats, socks), the filling in Zippo lighters, furnishings (e.g. bedspreads, bedsheets, blankets, window treatments, upholstery, slipcovers), industrial uses (e.g. medical surgery products, non-woven products, tire cord), and other uses (e.g. yarn, feminine hygiene products, diapers, towels).[3] Rayon is a major feedstock in the production of carbon fiber.[citation needed]
The fact that nitrocellulose is soluble in organic solvents such as ether and acetone made it possible for Georges Audemars to develop the first "artificial silk" in about 1855, but his method was impractical for commercial use. Commercial production started in 1891, but the result was flammable and more expensive than acetate or cuprammonium rayon. Because of this, production was stopped before World War I. It was briefly known as "mother-in-law silk."[4] Nathan Rosenstein invented the spunize process by which he turned rayon from a hard fiber to a fabric. This allowed rayon to become a popular raw material in textiles.
Paul Schützenberger discovered that cellulose could be reacted with acetic anhydride to form cellulose acetate. The triacetate is only[citation needed] soluble in chloroform making the method expensive. The discovery that hydrolyzed cellulose acetate is soluble in more polar solvents, like acetone, made production of cellulose acetate fibers cheap and efficient.
The Swiss chemist Matthias Eduard Schweizer (1818-1860) discovered that tetraaminecopper dihydroxide could dissolve cellulose. Max Fremery and Johann Urban developed a method to produce carbon fibers for use in light bulbs in 1897.[5] Production of rayon for textiles started in 1899 in the Vereinigte Glanzstoff Fabriken AG in Oberbruch. Improvement[citation needed] by the J. P. Bemberg AG in 1904 made the artificial silk a product comparable to real silk.
Finally, in 1894, English chemist Charles Frederick Cross, and his collaborators Edward John Bevan, and Clayton Beadle patented their artificial silk, which they named "viscose", because the reaction product of carbon disulfide and cellulose in basic conditions gave a highly viscous solution of xanthate. The first commercial viscose rayon was produced by the UK company Courtaulds Fibers in 1905. Avtex Fibers Incorporated began selling their formulation in the United States in 1910. The name "rayon" was adopted in 1924, with "viscose" being used for the viscous organic liquid used to make both rayon and cellophane. In Europe, though, the fabric itself became known as "viscose," which has been ruled an acceptable alternative term for rayon by the U.S. Federal Trade Commission.
The method is able to use wood (cellulose and lignin) as a source of cellulose while the other methods need lignin-free cellulose as starting material. This makes it cheaper and therefore it was used on a larger scale than the other methods. Contamination of the waste water by carbon disulfide, lignin and the xanthates made this process detrimental to the environment. Rayon was only produced as a filament fiber until the 1930s when it was discovered that broken waste rayon could be used in staple fiber.
The physical properties of rayon were unchanged until the development of high-tenacity rayon in the 1940s. Further research and development led to the creation of high-wet-modulus rayon (HWM rayon) in the 1950s.[6] Research in the UK was centred on the government-funded British Rayon Research Association.
Rayon is a versatile fiber and has the same comfort properties as natural fibers. It can imitate the feel and texture of silk, wool, cotton and linen. The fibers are easily dyed in a wide range of colors. Rayon fabrics are soft, smooth, cool, comfortable, and highly absorbent, but they do not insulate body heat, making them ideal for use in hot and humid climates.[7]
The durability and appearance retention of regular rayon are low, especially when wet; also, rayon has the lowest elastic recovery of any fiber. However, HWM rayon is much stronger and exhibits higher durability and appearance retention. Recommended care for regular rayon is dry-cleaning only. HWM rayon can be machine washed.[6]
A sample of rayon from a skirt, photographed with a macro lens.
Regular rayon has lengthwise lines called striations and its cross-section is an indented circular shape. The cross-sections of HWM and cupra rayon are rounder. Filament rayon yarns vary from 80 to 980 filaments per yarn and vary in size from 40 to 5000 denier. Staple fibers range from 1.5 to 15 denier and are mechanically or chemically crimped. Rayon fibers are naturally very bright, but the addition of delustering pigments cuts down on this natural brightness.[6]
Regular rayon (or viscose) is the most widely produced form of rayon. This method of rayon production has been utilized since the early 1900s and it has the ability to produce either filament or staple fibers. The process is as follows:
High wet modulus rayon (HWM) is a modified version of viscose that has a greater strength when wet. It also has the ability to be mercerized like cotton. HWM rayons are also known as "polynosic"[clarification needed] or can be identified by the trade name Modal.[8]
High-tenacity rayon is another modified version of viscose that has almost twice the strength of HWM. This type of rayon is typically used for industrial purposes such as tire cord.[8]
Cupramonium rayon has properties similar to viscose but during production, the cellulose is combined with copper and ammonia (Schweizer's reagent). Due to the environmental effects of this production method, cupramonium rayon is no longer produced in the United States.[8]
The biodegradability of fibers in soil burial and sewage sludge was evaluated by Korean researchers who found that biodegradability decreased in the following order: rayon, cotton, acetate (meaning rayon decays more readily than cotton). The ability of individual rayon-based fabrics to repel water was negatively correlated with their speed of degradation (meaning the greater the water-repelling ability of the fibre, the slower it will decompose).[9]
Rising cotton prices in 2010 led clothing makers to begin replacing cotton with rayon in their fabrics. Designers such as Isaac Mizrahi have incorporated rayon into their newest designs. As demand for rayon increases, companies such as Fortress Paper have been investing in pulp mills to increase production. Rayon now sells for as much as $2.70 per pound, which has led to an increase in the retail price of clothing made with rayon, despite rayon's price advantage over cotton.[10]
Rayon has been accused by some as contributing to the destruction of rain forests[11] although rayon production can come from a wide variety of trees and most of its yearly production comes from renewable trees.[12][13]
In early 2010, the U.S. Federal Trade Commission warned several retailers that six major manufacturers were falsely labeling rayon products as "bamboo", in order to appeal to environmentally conscious consumers. While rayon may be produced with bamboo as a raw material, and the two may be used for similar fabrics (though natural bamboo is not as smooth), rayon is so far removed from bamboo by chemical processing that the two are entirely separate.[14]
Trade names are used within the rayon industry to determine the type of rayon used.
Bemberg, for example, is a trade name for cupramonium rayon developed by J. P. Bemberg that is now only produced in Italy due to United States Environmental Protection Agency regulations in the US.
Modal and Tencel are widely used forms of rayon produced by Lenzing AG which is based in northern Austria. Tencel, generic name lyocell, is made by a slightly different solvent recovery process, and is considered a different fiber by the US FTC.
Galaxy, Danufil, and Viloft are rayon brands produced by Kelheim Fibres, a German manufacturer.
Acordis is a major manufacturer of cellulose based fibers and yarns. Production facilities can be found throughout Europe, the U.S. and Brazil.[citation needed]
Visil rayon is a flame retardant form of viscose which has silica embedded in the fiber during manufacturing.
North American Rayon Corporation of Tennessee produced viscose rayon until its closure in the year 2000.[15]
Grasim of India is the largest producer of rayon in the world (claiming 24% market share). It has plants in Nagda, Kharach and Harihar – all in India, as well as joint ventures in Canada, Laos and China.[16]
For a description of the production method at a factory in Germany in World War II, see pages 152–155 of
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Nederlands (Dutch)
rayon, kunstzijde
Français (French)
n. - rayonne
Ελληνική (Greek)
n. - (ύφασμα) ρεγιόν, τεχνητό μετάξι
Português (Portuguese)
n. - raiom (m)
Русский (Russian)
искусственный шелк, вискоза
中文(简体)(Chinese (Simplified))
人造丝, 嫘萦, 人造纤维
中文(繁體)(Chinese (Traditional))
n. - 人造絲, 嫘縈, 人造纖維
العربيه (Arabic)
(الاسم) حرير يصنع من السليولوز
עברית (Hebrew)
n. - זהורית, משי מלאכותי
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