Misplaced Pages

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82-495: On 30 October 1941, the preliminary order for development of the B-35 Flying Wing bomber was confirmed, including engineering, testing, and most importantly a 60 ft (18 m) wingspan, one-third scale aircraft, designated N-9M. It was to be used in gathering data on flight performance and for familiarizing pilots with the program's radical, all-wing design. The first N-9M was ordered in the original contract, but this

164-413: A composite material . The sheets of wood are stacked such that each layer has its grain set typically (see below) perpendicular to its adjacent layers. This alternation of the grain is called cross-graining and has several important benefits: it reduces the tendency of wood to split when nailed at the edges; it reduces thickness swelling and shrinkage, providing improved dimensional stability; and it makes

246-428: A caveat along the lines of "not suitable for boat In India,marine ply is popularly called "Kitply" after the brand which popularised the concept of water proof marine plywood in the 1980"s. Other types of plywoods include fire-retardant, moisture-resistant, wire mesh, sign-grade, and pressure-treated. However, the plywood may be treated with various chemicals to improve the plywood's fireproofing. Each of these products

328-454: 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

410-642: A fuselage made of birch plywood sandwiching a balsa core, and using plywood extensively for the wings. Plywood was also used for the hulls in the hard-chine Motor Torpedo Boats (MTB) and Motor Gun Boats (MGB) built by the British Power Boat Company and Vosper 's, American PT boats , and the Higgins landing craft critical to the D-Day landings. The American designers Charles and Ray Eames are known for their plywood-based furniture, as

492-401: A good log, called a peeler, which is generally straighter and larger in diameter than one required for processing into dimensioned lumber by a sawmill . The log is laid horizontally and rotated about its long axis while a long blade is pressed into it, causing a thin layer of wood to peel off (much as a continuous sheet of paper from a roll). An adjustable nosebar, which may be solid or a roller,

574-402: A large number of other hardwoods. Flexible plywood is designed for making curved parts, a practice which dates back to the 1850s in furniture making. At 3 ⁄ 8 inch (9.5 mm) thick, mahogany three-ply "wiggle board" or "bendy board" come in 4 by 8 feet (1.2 m × 2.4 m) sheets with a very thin cross-grain central ply and two thicker exterior plies, either long grain on

656-467: 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

738-409: 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

820-431: A press at a temperature of at least 140 °C (284 °F), and at a pressure of up to 1.9 MPa (280 psi) (but more commonly 1.4 MPa [200 psi]) to form the plywood panel. The panel can then be patched, have minor surface defects such as splits or small knot holes filled, re-sized, sanded or otherwise refinished, depending on the market for which it is intended. Plywood for indoor use generally uses

902-419: 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

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984-498: A result, many manufacturers are turning to low formaldehyde-emitting glue systems, denoted by an "E" rating. Plywood produced to "E0" has effectively zero formaldehyde emissions. In addition to the glues being brought to the forefront, the wood resources themselves are becoming the focus of manufacturers, due in part to energy conservation, as well as concern for natural resources. There are several certifications available to manufacturers who participate in these programs. Programme for

1066-519: A single thick layer of wood. Understanding the industrial potential of laminated wood, he invented the rotary lathe . There is little record of the early implementation of the rotary lathe and the subsequent commercialization of plywood as we know it today, but in its 1870 edition, the French dictionary Robert describes the process of rotary lathe veneer manufacturing in its entry Déroulage . One can thus presume that rotary lathe plywood manufacturing

1148-540: A strong, specially laminated plywood . The central section (roughly equivalent to the fuselage ) was made of welded tubular steel. The aircraft were originally powered by two 290 hp (216 kW) Menasco C6S-1 "Buccaneer" inverted air-cooled straight-six engines , driving twin-bladed propellers , except for the N-9MB which was powered by two 300 hp (224 kW) Franklin XO-540-7 engines. The first flight of

1230-744: 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

1312-685: 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

1394-464: 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

1476-698: 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

1558-409: Is Finnish Architect Alvar Aalto and his firm Artek , while Phil Bolger has designed a wide range of boats built primarily of plywood. Jack Köper of Cape Town designed the plywood Dabchick sailing dinghy , which as of 2015 is still sailed by large numbers of teenagers. Plywood is often used to create curved surfaces because it can easily bend with the grain. Skateboard ramps often utilize plywood as

1640-423: Is a composite material manufactured from thin layers, or "plies", of wood veneer that have been stacked and glued together. It is an engineered wood from the family of manufactured boards, which include plywood, medium-density fibreboard (MDF), oriented strand board (OSB), and particle board (or chipboard). All plywoods bind resin and wood fibre sheets ( cellulose cells are long, strong and thin) to form

1722-502: 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 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

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1804-546: 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

1886-399: Is also a common European size for Baltic birch ply, and aircraft ply. Sizes on specialised plywood for concrete-forming can range from 15 ⁄ 64 to 13 ⁄ 16  in (6 to 21 mm), and a multitude of formats exist, though 15 × 750 × 1,500 mm (.59in × 30 × 59 in) (19/32in × 2 ft-6in × 4 ft-11in)

1968-431: 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 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

2050-533: Is designed to fill a need in industry. Baltic Birch plywood is a product of an area around the Baltic Sea. Originally manufactured for European cabinet makers but now popular in the United States as well. It is very stable composed of an inner void-free core of cross-banded birch plys with an exterior grade adhesive. The face veneers are thicker than traditional cabinet grade Plywood production requires

2132-473: 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 ,

2214-702: Is extremely strong and light. Howard Hughes' H-4 Hercules was constructed of plywood. The plane was built by the Hughes Aircraft Company employing a plywood-and-resin Duramold process. The specialized wood veneer was made by Roddis Manufacturing in Marshfield, Wisconsin . Usually faced with hardwood , including ash , oak , red oak , birch , maple , mahogany , shorea (often called lauan, meranti, or Philippine mahogany, though having no relation to true mahogany), rosewood , teak and

2296-509: Is from 1 ⁄ 8  to 3 inches (3.2–76.2 mm). The sizes of the most commonly used plywood sheets are 4 by 8 feet (1,220 mm × 2,440 mm) which was first used by the Portland Manufacturing Company, who developed modern veneer core plywood for the 1905 Portland World Fair. A common metric size for a sheet of plywood is 1200 × 2400 mm. 5 × 5 feet (1,500 × 1,500 mm)

2378-573: Is higher in the center of the panel, and at the outer fibres. Within Europe basic plywood can be divided into three main categories: birch plywood (density approx. 680 kg/m ), mixed plywood (density approx. 620 kg/m ) and conifer plywoods (density 460– 520 kg/m ). Different varieties of plywood exist for different applications: Softwood plywood is usually made either of cedar , Douglas fir or spruce , pine , and fir (collectively known as spruce-pine-fir or SPF) or redwood and

2460-506: Is made of mixed hardwood species of tropical timber . Originally from the Asian region, it is now also manufactured in African and South American countries. Tropical plywood is superior to softwood plywood due to its density, strength, evenness of layers, and high quality. It is usually sold at a premium in many markets if manufactured with high standards. Tropical plywood is widely used in

2542-508: Is made out of wood from dicot trees (oak, beech and mahogany) and used for demanding end uses. Hardwood plywood is characterized by its excellent strength, stiffness, durability and resistance to creep. It has a high planar shear strength and impact resistance, which make it especially suitable for heavy-duty floor and wall structures. Oriented plywood construction has a high wheel-carrying capacity. Hardwood plywood has excellent surface hardness, and damage- and wear-resistance. Tropical plywood

Northrop N-9M - Misplaced Pages Continue

2624-665: 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

2706-564: Is manufactured to a number of specifications including those outlined since 1931 in the Germanischer Lloyd Rules for Surveying and Testing of Plywood for Aircraft and MIL-P-607, the latter of which calls for shear testing after immersion in boiling water for three hours to verify the adhesive qualities between the plies meets specifications. Aircraft grade plywood is made from three or more plies of birch, as thin as 0.40 millimetres ( 1 ⁄ 64  in) thick in total, and

2788-539: Is pressed against the log during rotation, to create a "gap" for veneer to pass through between the knife and the nosebar. The nosebar partly compresses the wood as it is peeled; it controls vibration of the peeling knife; and assists in keeping the veneer being peeled to an accurate thickness. In this way the log is peeled into sheets of veneer, which are then cut to the desired oversize dimensions, to allow it to shrink (depending on wood species) when dried. The sheets are then patched, graded, glued together and then baked in

2870-405: 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

2952-448: 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

3034-434: 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

3116-435: 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 a wide variety of derivative products such as cellophane and rayon . Conversion of cellulose from energy crops into biofuels such as cellulosic ethanol

3198-608: Is typically used as a ready-to-install component e.g.: Birch plywood is used as a structural material in special applications e.g.: Smooth surface and accurate thickness combined with the durability of the material makes birch plywood a favorable material for many special end uses e.g.: Tropical plywood is widely available from the South-East Asia region, mainly from Malaysia and Indonesia . "MR BWR BWP PLYWOOD PLYWOOD" https://www.toshgold.in/blogs/types-of-plywood  ; BY Tosh gold Cellulose Cellulose

3280-530: Is typically used for construction and industrial purposes. The most common dimension is 1.2 by 2.4 metres (3 ft 11 in × 7 ft 10 in) or the slightly larger imperial dimension of 4 feet × 8 feet. Plies vary in thickness from 1.4 mm to 4.3 mm. The number of plies—which is always odd—depends on the thickness and grade of the sheet. Roofing can use the thinner 16-millimetre ( 5 ⁄ 8  in) plywood. Subfloors are at least 19 millimetres ( 3 ⁄ 4  in) thick,

3362-426: 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 the help of symbiotic micro-organisms that live in their guts, such as Trichonympha . In human nutrition , cellulose

Northrop N-9M - Misplaced Pages Continue

3444-438: Is very commonly used. Aircraft plywood is available in thicknesses of 1 ⁄ 8 inch (3 mm) (3-ply construction) and upwards; typically aircraft plywood uses veneers of 0.5 mm (approx 1/64 in) thickness although much thinner veneers such as 0.1 mm are also used in construction of some of the thinner panels. Grading rules differ according to the country of origin. The most popular standards are

3526-495: 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

3608-412: 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

3690-413: 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, is odorless, is hydrophilic with the contact angle of 20–30 degrees, is insoluble in water and most organic solvents ,

3772-539: The British Standard (BS) and the American Standard (ASTM). Joyce (1970), however, list some general indication of grading rules: Plywood is used in many applications that need high-quality, high-strength sheet material. Quality in this context means resistance to cracking, breaking, shrinkage, twisting and warping. Exterior glued plywood is suitable for outdoor use, but because moisture affects

3854-538: The Endorsement of Forest Certification (PEFC) Forest Stewardship Council (FSC), Leadership in Energy and Environmental Design (LEED), Sustainable Forestry Initiative (SFI), and Greenguard are all certification programs that ensure that production and construction practices are sustainable. Many of these programs offer tax benefits to both the manufacturer and the end user. The most commonly used thickness range

3936-585: The N-9M occurred on 27 December 1942 with Northrop test pilot John Myers at the controls. During the next five months, 45 flights were made. Nearly all were terminated by various mechanical failures, the Menasco engines being the primary source of the problems. After roughly 22.5 hours of accumulated flight time, the first N-9M crashed approximately 12 miles (19 km) west of Muroc Army Air Base (now Edwards Air Force Base ) on 19 May 1943. The pilot, Max Constant,

4018-632: The N-9MB was destroyed shortly after takeoff, when it crashed into a prison yard in Norco, California . The pilot was killed but no ground casualties were reported. The National Transportation Safety Board attributed the crash to the "pilot's loss of control for undetermined reasons", stating that "given the significant fragmentation of the wreckage, the reason for the loss of control could not be determined". General characteristics Performance Related development Aircraft of comparable role, configuration, and era Plywood Plywood

4100-608: The UK, Japan, United States, Taiwan, Korea, Dubai, and other countries worldwide. It is used for construction purposes in many regions due to its low cost. However, many countries' forests have been over-harvested, including the Philippines, Malaysia and Indonesia, largely due to the demand for plywood production and export. High-strength plywood, also known as aircraft plywood, is made from mahogany, spruce and/or birch using adhesives with an increased resistance to heat and humidity. It

4182-536: 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

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4264-526: The ancient Greek verb πλέκω . The ancient Egyptians and Greeks cut wood thinly and glued it together in layers with the grain in perpendicular directions as fine wood was in short supply. This is believed to have been done purely for cosmetic and economical purposes but it turned out to be a great alternative to pure wood as it reduced flex, making it a versatile building material. In 1797 Samuel Bentham applied for patents covering several machines to produce veneers. In his patent applications, he described

4346-410: 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

4428-446: 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

4510-450: 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

4592-446: 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

4674-557: 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

4756-447: The chance of trapping water in the plywood and hence providing a solid and stable glue bond. It uses an exterior Weather and Boil Proof (WBP) glue similar to most exterior plywoods. Marine plywood can be graded as being compliant with BS 1088 , which is a British Standard for marine plywood and IS:710 is Bureau of Indian Standards (BIS) for marine grade plywood. There are few international standards for grading marine plywood and most of

4838-574: The concept of laminating several layers of veneer with glue to form a thicker piece – the first description of what we now call plywood. Bentham was a British naval engineer with many shipbuilding inventions to his credit. Veneers at the time of Bentham were flat sawn , rift sawn or quarter sawn ; i.e. cut along or across the log manually in different angles to the grain and thus limited in width and length. About fifty years later Immanuel Nobel , father of Alfred Nobel , realized that several thinner layers of wood bonded together would be stronger than

4920-412: The form of an alcoholic solution or powder, which, however, did not provide sufficient accuracy of application. Around 1930 a dry process of gluing veneers to plywood with phenolic resin in form of a film has begun to spread in the production of waterproof plywood. A typical plywood panel has face veneers of a higher grade than the core veneers. The principal function of the core layers is to increase

5002-469: The less expensive urea-formaldehyde glue, which has limited water resistance, while outdoor and marine-grade plywood are designed to withstand moisture, and use a water-resistant resorcinol-formaldehyde or phenol-formaldehyde glue to prevent delamination and to retain strength in high humidity . The adhesives used in plywood have become a point of concern. Both urea formaldehyde and phenol formaldehyde are carcinogenic in very high concentrations. As

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5084-602: 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

5166-508: 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

5248-461: The original material was not strictly plywood, but a single sheet of veneer. Marine plywood is manufactured from durable face and core veneers, with few defects so it performs longer in both humid and wet conditions and resists delaminating and fungal attack. Its construction is such that it can be used in environments where it is exposed to moisture for long periods. Each wood veneer will be from tropical hardwoods and have negligible core gap, limiting

5330-445: The separation between the outer layers where the bending stresses are highest, thus increasing the panel's resistance to bending . As a result, thicker panels can span greater distances under the same loads. In bending, the maximum stress occurs in the outermost layers, one in tension , the other in compression . Bending stress decreases from the maximum at the face layers to nearly zero at the central layer. Shear stress , by contrast,

5412-548: The sheet, or cross grain. Wiggle board is often glued together in two layers once it is formed into the desired curve, so that the final shape will be stiff and resist movement. Often, decorative wood veneers are added as a surface layer. In the United Kingdom single-ply sheets of veneer were used to make stove pipe hats in Victorian times, so flexible modern plywood is sometimes known there as "hatters ply", although

5494-421: The standards are voluntary. Some marine plywood has a Lloyd's of London stamp that certifies it to be BS 1088 compliant. Some plywood is also labeled based on the wood used to manufacture it. Examples of this are Okoumé or Meranti . In the UK, one can find builders' merchants advertising a grade of ply as "marine ply" that does not conform to BS 1088 - generally online adverts for these products will include

5576-410: The strength of the panel consistent across all directions. There is usually an odd number of plies, so that the sheet is balanced, that is, the surface layers have their grains set parallel to one another. This balance reduces warping. Because plywood is bonded with grains running against one another and with an odd number of composite parts, it has high stiffness perpendicular to the grain direction of

5658-501: The strength of wood, optimal performance is achieved where the moisture content remains relatively low. Subzero conditions do not affect the dimensional or strength properties of plywood, making some special applications possible. Plywood is also used as an engineering material for stressed-skin applications. It has been used for marine and aviation applications since WWII. Most notable is the British de Havilland Mosquito bomber, with

5740-453: The surface ply. Smaller, thinner, and lower-quality plywoods may only have their plies (layers) arranged at right angles to each other. Some better-quality plywood products by design have five plies in steps of 45 degrees (0, 45, 90, 135, and 180 degrees), giving strength in multiple axes. The word ply derives from the French verb plier , "to fold", from the Latin verb plico , from

5822-404: The thickness depending on the distance between floor joists . Plywood for flooring applications is often tongue and groove (T&G); This prevents one board from moving up or down relative to its neighbor, providing a solid-feeling floor when the joints do not lie over joists. T&G plywood is usually found in the 13-to-25-millimetre ( 1 ⁄ 2 to 1 in) range. Hardwood plywood

5904-443: The top smooth surface over bent curves to create transition that can simulate the shapes of ocean waves. Typical end uses of spruce plywood are: There are coating solutions available that mask the prominent grain structure of spruce plywood. For these coated plywoods there are some end uses where reasonable strength is needed but the lightness of spruce is a benefit, e.g.: Phenolic resin film coated (Film Faced) hardwood plywood

5986-524: 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

6068-430: 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

6150-423: The yellow-and-blue Flying Wing has been exhibited, with flight demonstrations at several airshows every year. In April 2006, the N-9MB suffered an in-flight engine fire. The aircraft was landed safely with limited damage. Donations to the museum were solicited for its repair, and the aircraft was fully repaired to flight status. It was flown again during the annual Chino airshow on 15–16 May 2010. On 22 April 2019,

6232-746: Was an established process in France in the 1860s. Plywood was introduced into the United States in 1865 and industrial production there started shortly after. In 1928, the first standard-sized 4 ft by 8 ft (1.22 m by 2.44 m) plywood sheets were introduced in the United States for use as a general building material. Artists use plywood as a support for easel paintings to replace traditional canvas or cardboard. Ready-made artist boards for oil painting in three-layered plywood (3-ply) were produced and sold in New York as early as 1880. There were experiments with gluing plywood with phenolic resins, mostly in

6314-478: Was canceled, all remaining N-9M flight test aircraft, except for the final N-9MB, were scrapped. For more than three decades, it slowly deteriorated until the Chino, California Planes of Fame Air Museum acquired the aircraft in 1982 and began the labor-intensive restoration process. For the next two decades, former Northrop employees and other volunteers restored the N-9MB to its final flight configuration. Since 1993,

6396-490: Was formed in two separate mirror-image halves, using curved moulds. Structural aircraft-grade plywood is most commonly manufactured from African mahogany, spruce or birch veneers that are bonded together in a hot press over hardwood cores of basswood or poplar or from European Birch veneers throughout. Basswood is another type of aviation-grade plywood that is lighter and more flexible than mahogany and birch plywood but has slightly less structural strength. Aviation-grade plywood

6478-449: Was killed as he attempted to recover the aircraft from a right-hand, 60° nose-down spin. The investigation found that Constant had suffered control reversal , the control column had been pressed against his chest during his recovery attempt from the steep spin, preventing him from parachuting to safety. Actions were taken to fix this problem and prevent it from happening on other N-9M test aircraft. When Northrop's Flying Wing bomber program

6560-496: Was later expanded to three test aircraft in early 1943. A fourth was ordered a few months later after a crash of the first N-9M destroyed that airframe; this fourth N-9M incorporated various flight test-derived improvements and upgrades, including different, more powerful engines. The four aircraft were designated N-9M-1 , -2 , -A , and -B , respectively. The N-9M framework was partially constructed of wood to reduce its overall weight. The wings' outer surfaces were also skinned with

6642-409: 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

6724-439: Was used in the construction of air assault gliders during World War II and also several fighter aircraft , most notably the multi-role British Mosquito . Nicknamed "The Wooden Wonder", plywood was used for the wing surfaces, and also flat sections such as bulkheads and the webs of the wing spars. The fuselage had exceptional rigidity from the bonded ply-balsa-ply 'sandwich' of its monocoque shell; elliptical in cross-section, it

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