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Rayon, also called viscose, is a semi-synthetic fiber made from natural sources of regenerated cellulose fiber, such as wood and related agricultural products. It has the same molecular structure as cellulose. Many types and grades of viscose fibers and films exist. Some imitate the feel and texture of such as silk, wool, cotton, and linen. The types that resemble silk are often called artificial silk. It can be woven or knit to make textiles for clothing and other purposes.
Rayon production involves solubilizing cellulose fibers. Three common methods are:
Swiss chemist Matthias Eduard Schweizer (1818–1860) discovered that cellulose dissolved in tetraamminecopper dihydroxide. Max Fremery and Johann Urban developed a method to produce carbon fibers for use in in 1897. Improvement of cuprammonium rayon for textiles by J. P. Bemberg in 1904 made the artificial silk a product comparable to real silk.
English chemist Charles Frederick Cross and his collaborators, Edward John Bevan and Clayton Beadle, patented their artificial silk in 1894. They named it "viscose" because its production involved the intermediacy of a highly viscous solution. Cross and Bevan took out British Patent No. 8,700, "Improvements in Dissolving Cellulose and Allied Compounds" in May, 1892. (2025). 9780203028292 ISBN 9780203028292 In 1893, they formed the Viscose Syndicate to grant licences and, in 1896, formed the British Viscoid Co. Ltd.
The first commercial viscose rayon was produced by the UK company Courtaulds in November 1905. Courtaulds formed an American division, American Viscose (later known as Avtex Fibers), to produce their formulation in the US in 1910.
Manufacturers' search for a less environmentally-harmful process for making rayon led to the development of the Lyocell method for producing rayon. The Lyocell process was developed in 1972 by a team at the now defunct American Enka fibers facility at Enka, North Carolina. In 2003, the American Association of Textile Chemists and Colorists (AATCC) awarded Neal E. Franks their Henry E. Millson Award for Invention for Lyocell. In 1966–1968, D. L. Johnson of Eastman Kodak Inc. studied NMMO solutions. In the decade 1969 to 1979, American Enka tried unsuccessfully to commercialize the process. The operating name for the fibre inside the Enka organization was "Newcell", and the development was carried through pilot plant scale before the work was stopped. The basic process of dissolving cellulose in NMMO was first described in a 1981 patent by Clarence McCorsley III for Akzona Incorporated (the holding company of Akzo). In the 1980s the patent was licensed by Akzo to Courtaulds and Lenzing. The fibre was developed by Courtaulds under the brand name "Tencel" in the 1980s. In 1982, a 100 kg/week pilot plant was built in Coventry, UK, and production was increased tenfold (to a ton/week) in 1984. In 1988, a 25 ton/week semi-commercial production line opened at the Grimsby, UK, pilot plant. The process was commercialized at Courtaulds' rayon factories at Mobile, Alabama. In January 1993, the Mobile Tencel plant reached full production levels of 20,000 tons per year, by which time Courtaulds had spent £100 million and 10 years on Tencel development. Tencel revenues for 1993 were estimated as likely to be £50 million. A second plant in Mobile was planned. By 2004, production had quadrupled to 80,000 tons.
Lenzing began a pilot plant in 1990, and commercial production in 1997, with 12 metric tonnes per year made in a plant in Heiligenkreuz im Lafnitztal, Austria. When an explosion hit the plant in 2003 it was producing 20,000 tonnes/year, and planning to double capacity by the end of the year. In 2004 Lenzing was producing 40,000 sic,. In 1998, Lenzing and Courtaulds reached a patent dispute settlement.
In 1998 Courtaulds was acquired by competitor Akzo Nobel, which combined the Tencel division with other fibre divisions under the Accordis banner, then sold them to private equity firm CVC Partners. In 2000, CVC sold the Tencel division to Lenzing AG, which combined it with their "Lenzing Lyocell" business, but maintained the brand name Tencel. It took over the plants in Mobile and Grimsby, and by 2015 were the largest lyocell producer at 130,000 tonnes/year.
C6H7O2(OH)3n + HNO3 ↔ C6H7O2(NO3)3n +H2O.
The sulfuric acid is used take up the water formed in the reaction leaving nitrocellulose.
Tetraamminecopper(II) sulfate is also used as a solvent.
The viscose method can use wood as a source of cellulose, whereas other routes to rayon require lignin-free cellulose as a starting material. The use of woody sources of cellulose makes viscose cheaper, so it was traditionally used on a larger scale than the other methods. On the other hand, the original viscose process generates large amounts of contaminated wastewater. Newer technologies use less water and have improved the quality of the wastewater.
The raw material for viscose is primarily wood pulp (sometimes Bamboo textile), which is chemically converted into a soluble compound. It is then dissolved and forced through a spinneret to produce filaments, which are chemically solidified, resulting in fibers of nearly pure cellulose. Unless the chemicals are handled carefully, workers can be seriously harmed by the carbon disulfide used to manufacture most rayon.
To prepare viscose, pulp is treated with aqueous sodium hydroxide (typically 16–19% by mass) to form Mercerisation, which has the approximate formula C6H9O4−ONa. This material is allowed to Polymer to an extent. The rate of depolymerization (ripening or maturing) depends on temperature and is affected by the presence of various inorganic additives, such as metal oxides and hydroxides. Air also affects the ripening process, since oxygen causes depolymerization. The alkali cellulose is then treated with carbon disulfide to form sodium cellulose xanthate:
Rayon fiber is produced from the ripened solutions by treatment with a mineral acid, such as sulfuric acid. In this step, the xanthate groups are hydrolyzed to regenerate cellulose and carbon disulfide:
Aside from regenerated cellulose, acidification gives hydrogen sulfide (H2S), sulfur, and carbon disulfide. The thread made from the regenerated cellulose is washed to remove residual acid. The sulfur is then removed by the addition of sodium sulfide solution, and impurities are oxidized by bleaching with sodium hypochlorite solution or hydrogen peroxide solution.
Production begins with processed cellulose obtained from wood pulp and plant fibers. The cellulose content in the pulp should be around 87–97%.
The process starts with cellulose and involves dry-jet wet spinning. It was developed at the now defunct American Enka Company and Courtaulds Fibres. Lenzing's Tencel is an example of a Lyocell fiber. Unlike the viscose process, the lycocell process does not use highly toxic carbon disulfide. "Lyocell" has become a genericized trademark, used to refer to the Lyocell process for making cellulose fibers.
the Lyocell process is not widely used, because it is still more expensive than the viscose process.
The durability and appearance retention of regular viscose rayons are low, especially when wet; also, rayon has the lowest elastic recovery of any fiber. However, HWM rayon (high-wet-modulus rayon) is much stronger and exhibits higher durability and appearance retention. Recommended care for regular viscose rayon is dry-cleaning only. HWM rayon can be machine-washed. (2025). 9780130254436, Prentice Hall. ISBN 9780130254436
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. rayon 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.
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.
Industrial applications of rayon emerged around 1935. Substituting cotton fiber in tires and belts, industrial types of rayon developed a totally different set of properties, amongst which tensile strength and elastic modulus were paramount.
is a genericized trademark of Lenzing AG, used for (viscose) rayon which is stretched as it is made, aligning the molecules along the fibers. Two forms are available: "polynosics" and "high wet modulus" (HWM). High-wet-modulus rayon is a modified version of viscose that is stronger when wet. It can be mercerized like cotton. HWM rayons are also known as "polynosic". Polynosic fibers are dimensionally stable and do not shrink or get pulled out of shape when wet like many rayons. They are also wear-resistant and strong while maintaining a soft, silky feel. They are sometimes identified by the trade name Modal. Modal is used alone or with other fibers (often cotton or spandex) in clothing and household items like pajamas, underwear, bathrobes, towels, and bedsheets. Modal can be Clothes dryer without damage. The fabric has been known to pill less than cotton due to fiber properties and lower surface friction. The trademarked Modal is made by spinning beech-tree cellulose and is considered a more eco-friendly alternative to cotton, as the production process uses on average 10–20 times less water.
Bemberg is a trade name for cuprammonium rayon developed by J. P. Bemberg. Bemberg performs much like viscose but has a smaller diameter and comes closest to silk in feel. Bemberg is now only produced in Japan. The fibers are finer than viscose rayon.
Modal and Tencel are widely used forms of rayon produced by Lenzing AG. Tencel, generic name Lyocell, is made by a slightly different solvent recovery process, and is considered a different fiber by the US Federal Trade Commission (FTC). Tencel Lyocell was first produced commercially by Courtaulds' Grimsby plant in England. The process, which dissolves cellulose without a chemical reaction, was developed by Courtaulds Research.
Birla Cellulose is also a volume manufacturer of rayon. They have plants located in India, Indonesia and China.
Accordis was a major manufacturer of cellulose-based fibers and yarns. Production facilities can be found throughout Europe, the U.S. and Brazil.
Visil rayon and HOPE FR are flame retardant forms of viscose that have Silicon dioxide embedded in the fiber during manufacturing.
North American Rayon Corporation of Tennessee produced viscose rayon until its closure in the year 2000.
Indonesia is one of the largest producers of rayon in the world, and Asia Pacific Rayon (APR) of the country has an annual production capacity of 0.24 million tons.
A 2014 ocean survey found that rayon contributed to 56.9% of the total fibers found in deep sea areas, the rest being polyester, polyamides, acetate and acrylic fiber. A 2016 study found a discrepancy in the ability to identify natural fibers in a marine environment via Fourier transform infrared spectroscopy. Later research of oceanic microfibers instead found cotton being the most frequent match (50% of all fibers), followed by other cellulosic fibers at 29.5% (e.g., rayon/viscose, linen, jute, kenaf, hemp, etc.). Further analysis of the specific contribution of rayon to ocean fibers was not performed due to the difficulty in distinguishing between natural and man-made cellulosic fibers using FTIR spectra.
For several years, there have been concerns about links between rayon manufacturers and deforestation. As a result of these concerns, FSC and PEFC came on the same platform with CanopyPlanet to focus on these issues. CanopyPlanet subsequently started publishing a yearly Hot Button report, which puts all the man-made cellulosics manufacturers globally on the same scoring platform. The scoring from the 2020 report scores all such manufacturers on a scale of 35, the highest scores having been achieved by Birla Cellulose (33) and Lenzing AG (30.5).
Most global carbon disulfide emissions come from rayon production, as of 2008. about 250 g of carbon disulfide is emitted per kilogram of rayon produced.
Control technologies have enabled improved collection of carbon disulfide and reuse of it, resulting in a lower emissions of carbon disulfide. These have not always been implemented in places where it was not legally required and profitable.
Carbon disulfide is volatile and is lost before the rayon gets to the consumer; the rayon itself is basically pure cellulose.
Studies from the 1930s showed that 30% of American rayon workers experienced significant health impacts due to carbon disulfide exposure. Courtaulds worked hard to prevent this information being published in Britain.
During the Second World War, political prisoners in Nazi Germany were made to work in appalling conditions at the Phrix rayon factory in Krefeld.Agnès Humbert, Notre Guerre (1946), translated into English by Barbara Mellor as Résistance, Memoirs of Occupied France Kitson's review of Résistance in New York Sun Nazis used Zwangsarbeiter to produce rayon across occupied Europe.
In the 1990s, viscose rayon producers faced lawsuits for negligent environmental pollution. Emissions abatement technologies had been consistently used. Carbon-bed recovery, for instance, which reduces emissions by about 90%, was used in Europe, but not in the US, by Courtaulds. Pollution control and worker safety started to become cost-limiting factors in production.
Japan has reduced carbon disulfide emissions per kilogram of viscose rayon produced (by about 16% per year), but in other rayon-producing countries, including China, emissions are uncontrolled. Rayon production is steady or decreasing except in China, where it is increasing,
Rayon production has largely moved to the developing world, especially China, Indonesia and India. Rates of disability in these factories are unknown, and concerns for worker safety continue.
Nitrocellulose is a derivative of cellulose that is soluble in organic solvents. It is mainly used as an explosive or as a lacquer. Many early plastics, including celluloid, were made from nitrocellulose.
Cellulose acetate shares many traits with viscose rayon and was formerly considered the same textile. However, rayon resists heat, while acetate is prone to melting. Acetate must be laundered with care either by hand-washing or dry cleaning, and acetate garments disintegrate when heated in a tumble dryer. The two fabrics are now required to be listed distinctly on US garment labels.
Cellophane is generally made by the viscose process, but dried into sheets instead of fibers.
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