Misplaced Pages

#867132

43-449: Rayon production involves solubilizing cellulose to allow turning the fibers into required form. Three common solubilization methods are: French scientist and industrialist Hilaire de Chardonnet (1838–1924) invented the first artificial textile fiber, artificial silk . Swiss chemist Matthias Eduard Schweizer (1818–1860) discovered that cellulose dissolved in tetraamminecopper dihydroxide . Max Fremery and Johann Urban developed

86-455: 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 " alkali cellulose ", which has the approximate formula [C 6 H 9 O 4 −ONa] n . This material

129-407: 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

172-557: 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

215-659: A method to produce carbon fibers for use in light bulbs in 1897. Production of cuprammonium rayon for textiles started in 1899 in the Vereinigte Glanzstoff Fabriken AG in Oberbruch (near Aachen ). Improvement by J. P. Bemberg AG 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

258-503: A pilot plant in 1990, and commercial production in 1997, with 12 metric tonnes/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 tons [sic, probably metric tonnes]. In 1998, Lenzing and Courtaulds reached a patent dispute settlement. In 1998 Courtaulds

301-473: A reaction with an acid. Micellar solubilization is widely utilized, e.g. in laundry washing using detergents , in the pharmaceutical industry, for formulations of poorly soluble drugs in solution form, and in cleanup of oil spills using dispersants . Literature distinguishes two major mechanisms of solubilization process of oil by surfactant micelles, affecting the kinetics of solubilization: surface reaction, i.e., by transient adsorption of micelles at

344-405: 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 tumble-dried without damage. The fabric has been known to pill less than cotton due to fiber properties and lower surface friction. The trademarked Modal

387-411: A solvent, N-methyl morpholine N-oxide (NMMO). 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

430-479: A wide range of colors. Rayon fabrics are soft, smooth, cool, comfortable, and highly absorbent, but they do not always insulate body heat, making them ideal for use in hot and humid climates, although also making their "hand" (feel) cool and sometimes almost slimy to the touch. 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)

473-403: Is allowed to depolymerize 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

SECTION 10

#1732790093868

516-408: Is distinct from a true solution , and the amount of the solubilizate in the micellar system can be different (often higher) than the regular solubility of the solubilizate in the solvent. In non-chemical literature and in everyday language, the term "solubilization" is sometimes used in a broader meaning as "to bring to a solution or (non- sedimenting ) suspension" by any means, e.g., leaching by

559-433: 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

602-597: Is made by a slightly different solvent recovery process, and is considered a different fiber by the US 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

645-411: 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. In 2018, viscose fiber production in the world was approximately 5.8 million tons, and China was the largest producer with about 65% of total global production. Trade names are used within the rayon industry to label the type of rayon in

688-575: 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. 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

731-438: Is produced by dissolving cellulose, then converting this solution back to insoluble fibrous cellulose. Various processes have been developed for this regeneration. The most common methods for creating rayon are the cuprammonium method, the viscose method, and the lyocell process. The first two methods have been practiced for more than a century. Cuprammonium rayon has properties similar to viscose; however, during its production,

774-401: 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 (H 2 S), sulfur, and carbon disulfide. The thread made from the regenerated cellulose is washed to remove residual acid. The sulfur

817-471: 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

860-431: Is the process of incorporating the solubilizate (the component that undergoes solubilization) into or onto micelles . Solubilization may occur in a system consisting of a solvent , an association colloid (a colloid that forms micelles), and at least one other solubilizate. Solubilization is distinct from dissolution because the resulting fluid is a colloidal dispersion involving an association colloid. This suspension

903-401: 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 steps: The lyocell process relies on dissolution of cellulose products in

SECTION 20

#1732790093868

946-419: The firebrat —can eat rayon, but damage was found to be minor, potentially due to the heavy, slick texture of the tested rayon. Another study states that "artificial silk [...] [was] readily eaten" by the grey silverfish . A 2014 ocean survey found that rayon contributed to 56.9% of the total fibers found in deep ocean areas, the rest being polyester , polyamides , acetate and acrylic . A 2016 study found

989-719: The 1930s show 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 . Nazis used forced labour to produce rayon across occupied Europe. In

1032-509: The 1980s the patent was licensed by Akzo to Courtaulds and Lenzing. The fibre was developed by Courtaulds Fibres 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

1075-548: 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. Solubilizing Micellar solubilization ( solubilization )

1118-573: The US 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 US Federal Trade Commission (FTC). Rayon was produced only as a filament fiber until the 1930s, when methods were developed to utilize "broken waste rayon" as staple fiber. Manufacturers' search for

1161-505: The addition of delustering pigments cuts down on this natural brightness. The physical properties of rayon remained unchanged until the development of high-tenacity rayon in the 1940s. Further research and development led to high-wet-modulus rayon (HWM rayon) in the 1950s. Research in the UK was centred on the government-funded British Rayon Research Association . High-tenacity rayon is another modified version of viscose that has almost twice

1204-534: The cellulose is combined with copper and ammonia ( Schweizer's reagent ). Due to the detrimental environmental effects of this production method, cuprammonium rayon is no longer being produced in the United States . The process has been described as obsolete, but cuprammonium rayon is still made by one company in Japan. Tetraamminecopper(II) sulfate is also used as a solvent. The viscose process builds on

1247-515: 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 Mcorsley for Akzona Incorporated (the holding company of Akzo). In

1290-533: The health of people living near rayon plants and their livestock. Rates of disability in modern factories (mainly in China, Indonesia, and India) are unknown. This has raised ethical concerns over viscose rayon production. As of 2016, production facilities located in developing countries generally do not provide environmental or worker safety data. Most global carbon disulfide emissions come from rayon production, as of 2008. As of 2004, about 250 g of carbon disulfide

1333-824: 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. 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 Fibres in November 1905. Courtaulds formed an American division, American Viscose (later known as Avtex Fibers), to produce their formulation in

Rayon - Misplaced Pages Continue

1376-447: 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. The biodegradability of various fibers in soil burial and sewage sludge was evaluated by Korean researchers. Rayon was found to be more biodegradable than cotton, and cotton more than acetate . The more water-repellent the rayon-based fabric, the more slowly it will decompose. Silverfish —like

1419-464: The lyocell process for making cellulose fibers. As of 2018, the lyocell process is not widely used, because it is still more expensive than the viscose process. Rayon is a versatile fiber and is widely claimed to have the same comfort properties as natural fibers, although the drape and slipperiness of rayon textiles are often more like nylon . It can imitate the feel and texture of silk , wool , cotton , and linen . The fibers are easily dyed in

1462-411: 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 (30.5). Carbon disulfide is highly toxic . It is well documented to have seriously harmed the health of rayon workers in developed countries, and emissions may also harm

1505-463: The product. Viscose rayon was first produced in Coventry, England in 1905 by Courtaulds. 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 ,

1548-437: The reaction of cellulose with a strong base, followed by treatment of that solution with carbon disulfide to give a xanthate derivative. The xanthate is then converted back to a cellulose fiber in a subsequent step. 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

1591-434: 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. Modal is a genericized trademark of Lenzing AG , used for (viscose) rayon which

1634-501: The water-oil interface, and bulk reaction, whereby the surfactant micelles capture dissolved oil molecules. Solubilization of Homopolymers by Block Copolymer Micelles in Dilute Solutions, J. Phys. Chem., 1995, 99 (11), pp 3723–3731, Jose R. Quintana, Ramiro A. Salazar, Issa Katime Heiligenkreuz im Lafnitztal Heiligenkreuz im Lafnitztal ( Hungarian : Rábakeresztúr, Rába-Keresztúr , Slovene : Sveti Križ )

1677-403: 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 silica 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

1720-620: 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. Rayon

1763-590: Was first commercialized at Courtaulds' rayon factories at Mobile, Alabama (1990), and at the Grimsby plant (1998). 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

Rayon - Misplaced Pages Continue

1806-435: 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

1849-425: 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 pulp ), which is chemically converted into a soluble compound. It is then dissolved and forced through

#867132