Misplaced Pages

#181818

50-433: Cellophane is a thin, transparent sheet made of regenerated cellulose . Its low permeability to air , oils , greases , bacteria , and liquid water makes it useful for food packaging . Cellophane is highly permeable to water vapour , but may be coated with nitrocellulose lacquer to prevent this. Cellophane is also used in transparent pressure-sensitive tape , tubing, and many other similar applications. Cellophane

100-542: A nitrocellulose lacquer that, when applied to Cellophane, made it moisture proof. Following the introduction of moisture-proof Cellophane in 1927, the material's sales tripled between 1928 and 1930, and in 1938, Cellophane accounted for 10% of DuPont's sales and 25% of its profits. Cellophane played a crucial role in developing the self-service retailing of fresh meat. Cellophane visibility helped customers know quality of meat before buying. Cellophane also worked to consumers' disadvantage when manufacturers learned to manipulate

150-418: A certain type of battery , as dialysis tubing (Visking tubing), and as a release agent in the manufacture of fibreglass and rubber products. Cellophane is the most popular material for manufacturing cigar packaging; its permeability to water vapor makes cellophane a good product for this application as cigars must be allowed to "breathe" while wrapped and in storage. Cellophane sales have dwindled since

200-530: A cloth that could repel liquids rather than absorb them. His first step was to spray a waterproof coating onto fabric, and he opted to try viscose . The resultant coated fabric was far too stiff, but the diaphanous film coating could be separated from the backing cloth easily and in one undamaged piece. Seeing the possibilities of this new material on its own, Brandenberger soon abandoned his original idea. It took ten years for Brandenberger to perfect his film. His chief improvement over earlier work with such films

250-454: A crystalline to amorphous transition when heated beyond 60–70 °C in water (as in cooking), cellulose requires a temperature of 320 °C and pressure of 25 MPa to become amorphous in water. Several types of cellulose are known. These forms are distinguished according to the location of hydrogen bonds between and within strands. Natural cellulose is cellulose I, with structures I α and I β . Cellulose produced by bacteria and algae

300-423: A hole (a spinneret ) instead of a slit, is used to make a fibre called rayon . Chemically, cellophane, rayon, and cellulose are polymers of glucose ; they differ structurally rather than chemically. Cellophane was invented by Swiss chemist Jacques E. Brandenberger while employed by Blanchisserie et Teinturerie de Thaon . In 1900, inspired by seeing wine spill on a restaurant's tablecloth, he decided to create

350-467: A liquid called bio-oil is obtained at 500 °C. Semi-crystalline cellulose polymers react at pyrolysis temperatures (350–600 °C) in a few seconds; this transformation has been shown to occur via a solid-to-liquid-to-vapor transition, with the liquid (called intermediate liquid cellulose or molten cellulose ) existing for only a fraction of a second. Glycosidic bond cleavage produces short cellulose chains of two-to-seven monomers comprising

400-409: A polysaccharide matrix . The high tensile strength of plant stems and of the tree wood also arises from the arrangement of cellulose fibers intimately distributed into the lignin matrix. The mechanical role of cellulose fibers in the wood matrix responsible for its strong structural resistance, can somewhat be compared to that of the reinforcement bars in concrete , lignin playing here the role of

450-419: A proper solvent , e.g. in an ionic liquid . Most mammals have limited ability to digest dietary fibre such as cellulose. Some ruminants like cows and sheep contain certain symbiotic anaerobic bacteria (such as Cellulomonas and Ruminococcus spp. ) in the flora of the rumen , and these bacteria produce enzymes called cellulases that hydrolyze cellulose. The breakdown products are then used by

500-602: A resurgence in recent times due to its being biosourced, compostable, and biodegradable. Its sustainability record is clouded by its energy-intensive manufacturing process and the potential negative impact of some of the chemicals used, but significant progress in recent years has been made by leading manufacturers in reducing their environmental footprint. When placed between two plane polarizing filters, cellophane produces prismatic colours due to its birefringent nature. Artists have used this effect to create stained glass-like creations that are kinetic and interactive. Cellophane

550-744: A variety of uses. Nitrocellulose was initially used as an explosive and was an early film forming material. When plasticized with camphor , nitrocellulose gives celluloid . Cellulose Ether derivatives include: The sodium carboxymethyl cellulose can be cross-linked to give the croscarmellose sodium (E468) for use as a disintegrant in pharmaceutical formulations. Furthermore, by the covalent attachment of thiol groups to cellulose ethers such as sodium carboxymethyl cellulose, ethyl cellulose or hydroxyethyl cellulose mucoadhesive and permeation enhancing properties can be introduced. Thiolated cellulose derivatives (see thiomers ) exhibit also high binding properties for metal ions. Cellulose for industrial use

SECTION 10

#1732776025182

600-464: A wide variety of derivative products such as cellophane and rayon . Conversion of cellulose from energy crops into biofuels such as cellulosic ethanol is under development as a renewable fuel source. Cellulose for industrial use is mainly obtained from wood pulp and cotton . Cellulose is also greatly affected by direct interaction with several organic liquids. Some animals, particularly ruminants and termites , can digest cellulose with

650-685: A wide variety of products. While the first application of regenerated cellulose was as a clothing textile , this class of materials is also used in the production of disposable medical devices as well as fabrication of artificial membranes . The hydroxyl groups (−OH) of cellulose can be partially or fully reacted with various reagents to afford derivatives with useful properties like mainly cellulose esters and cellulose ethers (−OR). In principle, although not always in current industrial practice, cellulosic polymers are renewable resources. Ester derivatives include: Cellulose acetate and cellulose triacetate are film- and fiber-forming materials that find

700-698: Is (C 6 H 10 O 5 ) n where n is the degree of polymerization and represents the number of glucose groups. Plant-derived cellulose is usually found in a mixture with hemicellulose , lignin , pectin and other substances, while bacterial cellulose is quite pure, has a much higher water content and higher tensile strength due to higher chain lengths. Cellulose consists of fibrils with crystalline and amorphous regions. These cellulose fibrils may be individualized by mechanical treatment of cellulose pulp, often assisted by chemical oxidation or enzymatic treatment, yielding semi-flexible cellulose nanofibrils generally 200 nm to 1 μm in length depending on

750-546: Is a straight chain polymer. Unlike starch, no coiling or branching occurs and the molecule adopts an extended and rather stiff rod-like conformation, aided by the equatorial conformation of the glucose residues. The multiple hydroxyl groups on the glucose from one chain form hydrogen bonds with oxygen atoms on the same or on a neighbour chain, holding the chains firmly together side-by-side and forming microfibrils with high tensile strength . This confers tensile strength in cell walls where cellulose microfibrils are meshed into

800-470: Is an important structural component of the primary cell wall of green plants , many forms of algae and the oomycetes . Some species of bacteria secrete it to form biofilms . Cellulose is the most abundant organic polymer on Earth. The cellulose content of cotton fibre is 90%, that of wood is 40–50%, and that of dried hemp is approximately 57%. Cellulose is mainly used to produce paperboard and paper . Smaller quantities are converted into

850-657: Is as Insect repellents . You%27re the Top Porter is believed to have written the song in Paris, while eating dinner at the Le Bœuf sur le toit with Lela Emery, the wife of Alastair Mackintosh. The two of them spent the time amusing themselves with a word game , "making up a list of superlatives that rhymed." The following is a list of the references used in the version recorded by Cole Porter on November 26, 1934: The 1934 recording with Cole Porter's vocals and piano

900-497: Is available on a CD -- Cole Porter: A Centennial Collection (track 18 of 20), Sony Legacy, CD release 2007 Additional references in other versions of the song: P. G. Wodehouse anglicised it for the British version of Anything Goes . Among other changes, he altered two lines from "You’re an O’Neill drama / You’re Whistler’s mama!" to "You’re Mussolini / You’re Mrs Sweeny " (both figures, later notorious, were widely admired at

950-554: Is biodegradable, but highly toxic carbon disulfide is used in most cellophane production. Viscose factories vary widely in the amount of CS 2 they expose their workers to , and most give no information about their quantitative safety limits or how well they keep to them. In the UK and in many other countries, "Cellophane" is a registered trademark and the property of Futamura Chemical UK Ltd , based in Wigton , Cumbria , United Kingdom. In

1000-464: Is compostable and biodegradable, and can be obtained from biomaterials. The original production process uses carbon disulfide (CS 2 ), which has been found to be highly toxic to workers. The newer lyocell process can be used to produce cellulose film without involving carbon disulfide. "Cellophane" is a generic term in some countries, while in other countries it is a registered trademark . Cellulose from wood , cotton , hemp , or other sources

1050-446: Is dissolved in alkali and carbon disulfide to make a solution called viscose , which is then extruded through a slit into a bath of dilute sulfuric acid and sodium sulfate to reconvert the viscose into cellulose. The film is then passed through several more baths, one to remove sulfur , one to bleach the film, and one to add softening materials such as glycerin to prevent the film from becoming brittle. A similar process, using

SECTION 20

#1732776025182

1100-473: Is enriched in I α while cellulose of higher plants consists mainly of I β . Cellulose in regenerated cellulose fibers is cellulose II. The conversion of cellulose I to cellulose II is irreversible, suggesting that cellulose I is metastable and cellulose II is stable. With various chemical treatments it is possible to produce the structures cellulose III and cellulose IV. Many properties of cellulose depend on its chain length or degree of polymerization ,

1150-665: Is mainly obtained from wood pulp and from cotton . Energy crops: The major combustible component of non-food energy crops is cellulose, with lignin second. Non-food energy crops produce more usable energy than edible energy crops (which have a large starch component), but still compete with food crops for agricultural land and water resources. Typical non-food energy crops include industrial hemp , switchgrass , Miscanthus , Salix ( willow ), and Populus ( poplar ) species. A strain of Clostridium bacteria found in zebra dung, can convert nearly any form of cellulose into butanol fuel . Another possible application

1200-591: Is odorless, is hydrophilic with the contact angle of 20–30 degrees, is insoluble in water and most organic solvents , is chiral and is biodegradable . It was shown to melt at 467 °C in pulse tests made by Dauenhauer et al. (2016). It can be broken down chemically into its glucose units by treating it with concentrated mineral acids at high temperature. Cellulose is derived from D -glucose units, which condense through β(1→4)- glycosidic bonds . This linkage motif contrasts with that for α(1→4)-glycosidic bonds present in starch and glycogen . Cellulose

1250-405: Is produced using the same family of proteins, although the gene is called BcsA for "bacterial cellulose synthase" or CelA for "cellulose" in many instances. In fact, plants acquired CesA from the endosymbiosis event that produced the chloroplast . All cellulose synthases known belongs to glucosyltransferase family 2 (GT2). Cellulose synthesis requires chain initiation and elongation, and

1300-448: Is short for "cellulose synthase") genes, in an unknown stoichiometry . Separate sets of CesA genes are involved in primary and secondary cell wall biosynthesis. There are known to be about seven subfamilies in the plant CesA superfamily, some of which include the more cryptic, tentatively-named Csl (cellulose synthase-like) enzymes. These cellulose syntheses use UDP-glucose to form the β(1→4)-linked cellulose. Bacterial cellulose

1350-434: Is synthesized at the plasma membrane by rosette terminal complexes (RTCs). The RTCs are hexameric protein structures, approximately 25 nm in diameter, that contain the cellulose synthase enzymes that synthesise the individual cellulose chains. Each RTC floats in the cell's plasma membrane and "spins" a microfibril into the cell wall . RTCs contain at least three different cellulose synthases , encoded by CesA ( Ces

1400-495: The glycosidic linkage in cellulose are glycoside hydrolases including endo-acting cellulases and exo-acting glucosidases . Such enzymes are usually secreted as part of multienzyme complexes that may include dockerins and carbohydrate-binding modules . At temperatures above 350 °C, cellulose undergoes thermolysis (also called ' pyrolysis '), decomposing into solid char , vapors, aerosols , and gases such as carbon dioxide . Maximum yield of vapors which condense to

1450-412: The hardened cement paste acting as the "glue" in between the cellulose fibres. Mechanical properties of cellulose in primary plant cell wall are correlated with growth and expansion of plant cells. Live fluorescence microscopy techniques are promising in investigation of the role of cellulose in growing plant cells. Compared to starch, cellulose is also much more crystalline . Whereas starch undergoes

1500-417: The 1960s, due to alternative packaging options. The polluting effects of carbon disulfide and other by-products of the process used to make viscose may have also contributed to its falling behind lower cost petrochemical-based films such as biaxially-oriented polyethylene terephthalate (BoPET) and biaxially oriented polypropylene (BOPP) in the 1980s and 1990s. However, as of 2017, it has made something of

1550-545: The USA and some other countries "cellophane" has become genericized , and is often used informally to refer to a wide variety of plastic film products, even those not made of cellulose, such as PVC -based plastic wrap . Cellulose Cellulose is an organic compound with the formula ( C 6 H 10 O 5 ) n , a polysaccharide consisting of a linear chain of several hundred to many thousands of β(1→4) linked D -glucose units. Cellulose

Cellophane - Misplaced Pages Continue

1600-665: The United States in 1912 for their Whitman's Sampler . They remained the largest user of imported cellophane from France until nearly 1924, when DuPont built the first cellophane manufacturing plant in the US. Cellophane saw limited sales in the US at first since while it was waterproof, it was not moisture proof—it held or repelled water but was permeable to water vapor. This meant that it was unsuited to packaging products that required moisture proofing. DuPont hired chemist William Hale Charch (1898–1958), who spent three years developing

1650-536: The Viscose Development Company, is the most widely used method for manufacturing regenerated cellulose products. Courtaulds purchased the patents for this process in 1904, leading to significant growth of viscose fiber production. By 1931, expiration of patents for the viscose process led to its adoption worldwide. Global production of regenerated cellulose fiber peaked in 1973 at 3,856,000 tons. Regenerated cellulose can be used to manufacture

1700-499: The appearance of a product by controlling oxygen and moisture levels to prevent discolouration of food. It was considered such a useful invention that cellophane was listed alongside other modern marvels in the 1934 song " You're the Top " (from Anything Goes ). The British textile company Courtaulds ' viscose technology had allowed it to diversify in 1930 into viscose film, which it named "Viscacelle". However, competition with Cellophane

1750-410: The bacteria for proliferation. The bacterial mass is later digested by the ruminant in its digestive system ( stomach and small intestine ). Horses use cellulose in their diet by fermentation in their hindgut . Some termites contain in their hindguts certain flagellate protozoa producing such enzymes, whereas others contain bacteria or may produce cellulase. The enzymes used to cleave

1800-446: The basis of commercial technologies. These dissolution processes are reversible and are used in the production of regenerated celluloses (such as viscose and cellophane ) from dissolving pulp . The most important solubilizing agent is carbon disulfide in the presence of alkali. Other agents include Schweizer's reagent , N -methylmorpholine N -oxide , and lithium chloride in dimethylacetamide . In general, these agents modify

1850-450: The biomass of land plants . In contrast to cellulose, hemicelluloses are derived from several sugars in addition to glucose , especially xylose but also including mannose , galactose , rhamnose , and arabinose . Hemicelluloses consist of shorter chains – between 500 and 3000 sugar units. Furthermore, hemicelluloses are branched, whereas cellulose is unbranched. Cellulose is soluble in several kinds of media, several of which are

1900-446: The cellulose was historically termed "tunicine" (tunicin)). Cellulolysis is the process of breaking down cellulose into smaller polysaccharides called cellodextrins or completely into glucose units; this is a hydrolysis reaction. Because cellulose molecules bind strongly to each other, cellulolysis is relatively difficult compared to the breakdown of other polysaccharides . However, this process can be significantly intensified in

1950-557: The cellulose, rendering it soluble. The agents are then removed concomitant with the formation of fibers. Cellulose is also soluble in many kinds of ionic liquids . The history of regenerated cellulose is often cited as beginning with George Audemars, who first manufactured regenerated nitrocellulose fibers in 1855. Although these fibers were soft and strong -resembling silk- they had the drawback of being highly flammable. Hilaire de Chardonnet perfected production of nitrocellulose fibers, but manufacturing of these fibers by his process

2000-491: The help of symbiotic micro-organisms that live in their guts, such as Trichonympha . In human nutrition , cellulose is a non-digestible constituent of insoluble dietary fiber , acting as a hydrophilic bulking agent for feces and potentially aiding in defecation . Cellulose was discovered in 1838 by the French chemist Anselme Payen , who isolated it from plant matter and determined its chemical formula. Cellulose

2050-602: The melt. Vapor bubbling of intermediate liquid cellulose produces aerosols , which consist of short chain anhydro-oligomers derived from the melt. Continuing decomposition of molten cellulose produces volatile compounds including levoglucosan , furans , pyrans , light oxygenates, and gases via primary reactions. Within thick cellulose samples, volatile compounds such as levoglucosan undergo 'secondary reactions' to volatile products including pyrans and light oxygenates such as glycolaldehyde . Hemicelluloses are polysaccharides related to cellulose that comprises about 20% of

Cellophane - Misplaced Pages Continue

2100-508: The number of glucose units that make up one polymer molecule. Cellulose from wood pulp has typical chain lengths between 300 and 1700 units; cotton and other plant fibers as well as bacterial cellulose have chain lengths ranging from 800 to 10,000 units. Molecules with very small chain length resulting from the breakdown of cellulose are known as cellodextrins ; in contrast to long-chain cellulose, cellodextrins are typically soluble in water and organic solvents. The chemical formula of cellulose

2150-413: The time) Porter biographer William McBrien wrote that at the height of its popularity in 1934 to 1935 it had become a "popular pastime" to create parodies of the lyrics. Porter, who himself had called the song "just a trick" the public would get bored by, was flooded with hundreds of parodies, one reportedly written by Irving Berlin . Despite the ribald nature of some of the parodies, McBrien believes

2200-524: The treatment intensity. Cellulose pulp may also be treated with strong acid to hydrolyze the amorphous fibril regions, thereby producing short rigid cellulose nanocrystals a few 100 nm in length. These nanocelluloses are of high technological interest due to their self-assembly into cholesteric liquid crystals , production of hydrogels or aerogels , use in nanocomposites with superior thermal and mechanical properties, and use as Pickering stabilizers for emulsions . In plants cellulose

2250-430: The two processes are separate. Cellulose synthase ( CesA ) initiates cellulose polymerization using a steroid primer, sitosterol -beta- glucoside , and UDP-glucose. It then utilises UDP -D-glucose precursors to elongate the growing cellulose chain. A cellulase may function to cleave the primer from the mature chain. Cellulose is also synthesised by tunicate animals, particularly in the tests of ascidians (where

2300-409: The viscose solution), and in 1957 at Barrow-in-Furness , Cumbria. The latter two plants were closed in the 1990s. Cellulose film has been manufactured continuously since the mid-1930s and is still used today. As well as packaging a variety of food items, there are also industrial applications, such as a base for such self-adhesive tapes as Sellotape and Scotch Tape , a semi-permeable membrane in

2350-606: Was adding glycerin to soften the material. By 1912 he had constructed a machine to manufacture the film, which he had named Cellophane, from the words cellulose and diaphane ("transparent"). Cellophane was patented that year. The following year, the company Comptoir des Textiles Artificiels (CTA) bought the Thaon firm's interest in Cellophane and established Brandenberger in a new company, La Cellophane SA. Whitman's candy company initiated use of cellophane for candy wrapping in

2400-577: Was an obstacle to its sales, and in 1935 it founded British Cellophane Limited (BCL) in conjunction with the Cellophane Company and its French parent company CTA. A major production facility was constructed at Bridgwater , Somerset , England, from 1935 to 1937, employing 3,000 workers. BCL subsequently constructed plants in Cornwall, Ontario (BCL Canada), as an adjunct to the existing Courtaulds viscose rayon plant there (from which it bought

2450-409: Was relatively uneconomical. In 1890, L.H. Despeissis invented the cuprammonium process – which uses a cuprammonium solution to solubilize cellulose – a method still used today for production of artificial silk . In 1891, it was discovered that treatment of cellulose with alkali and carbon disulfide generated a soluble cellulose derivative known as viscose . This process, patented by the founders of

2500-473: Was used to produce the first successful thermoplastic polymer , celluloid , by Hyatt Manufacturing Company in 1870. Production of rayon ("artificial silk ") from cellulose began in the 1890s and cellophane was invented in 1912. Hermann Staudinger determined the polymer structure of cellulose in 1920. The compound was first chemically synthesized (without the use of any biologically derived enzymes ) in 1992, by Kobayashi and Shoda. Cellulose has no taste,

#181818