water, but soluble in acids and in solutions of ammonium salts. Nickel carbonyl, Ni(CO) 4 , used for nickel plating by gas decomposi- tion, is a yellow volatile liquid. It is volatilized in a closed vessel with hydrogen as the carrier, and the nickel is deposited at about 350°F (177°C). It will adhere to glass and wood as well as to metals. The material is a strong reducing agent and is explosive when mixed with oxygen. Nickel nitrate, (NiNO 3 ) 2 :6H 2 O, used in electric batteries, comes in thin, flat flakes. NITRIC ACID. Also called aqua fortis and azotic acid. A colorless to reddish, fuming liquid of composition HNO 3 , having a wide variety of uses for pickling metals, in etching, and in the manufacture of nitro- cellulose, plastics, dyestuffs, and explosives. It has a specific gravity of 1.502 (95% acid) and a boiling point of 187°F (86°C) and is soluble in water. Its fumes have a suffocating action, and it is highly corro- sive and caustic. Fuming nitric acid is any water solution contain- ing more than 86% acid and having a specific gravity above 1.480. Nitric acid is made by the action of sulfuric acid on sodium nitrate, or purified Chilean saltpeter, and condensation of the fumes. It is also made from ammonia by catalytic oxidation, or from the nitric oxide produced from air. The acid is sold in various grades depending on the amount of water. The strengths of the commercial grades are 38, 40, and 42°Bé, containing 67.2% acid. C.P., or reagent grade, is 43°Bé, with 70.3% acid, very low in iron, arsenic, or other impurities. It is usually shipped in glass carboys. Anhydrous nitric acid is a yellow fuming liquid containing the unstable anhydride nitrogen pentox- ide, N 2 O 5 , It is violently reactive and is a powerful nitriding agent. The dark-red fuming liquid known as nitrogen tetroxide, N 2 O 4 , is really a concentrated water solution of nitric acid, as this oxide is an unstable polymer of NO 2 . It is used as an oxidizer for rocket fuels, as it contains 70% oxygen. Mixed acid, or nitrating acid, is a mixture of nitric and sulfuric acids used chiefly in making nitrocellulose and nitrostarch. Standard mixed acid contains 36% nitric and 61 sulfuric acid, but other grades are also used. NITRIDING STEELS. Low- and medium-carbon steels with combina- tions of chromium and aluminum or nickel, chromium, and alu- minum. Nitriding consists of exposing steel parts to gaseous ammonia at about 1000°F (538°C) to form metallic nitrides at the surface. The hardest coatings are obtained with aluminum-bearing steels. Nitriding of stainless steel is known as Malcomizing. After nitrid- ing, these steels have extremely high surface hardnesses of about Rockwell N 92 to 95. The nitride layer also has considerable resis- 640 NITRIC ACID Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Materials, Their Properties and Uses tance to corrosion from alkalies, the atmosphere, crude oil, natural gas, combustion products, tap water, and still saltwater. Nitrided parts usually grow about 0.001 to 0.002 in (0.003 to 0.005 cm) during nitriding. The growth can be removed by grinding or lapping, which also removes the brittle surface layer. Most uses of nitrided steels are based on resistance to wear. The steels can be used at temperatures as high as 1000°F (538°C) for long periods without softening. The slick, hard, and tough nitrided surface also resists seizing, galling, and spalling. Typical applications are cylinder liners for aircraft engines, bushings, shafts, spindles and thread guides, cams, and rolls. A composition range of Nitralloy steel is 0.20 to 0.45% carbon, 0.75 to 1.5 aluminum, 0.9 to 1.8 chromium, 0.4 to 0.70 manganese, 0.15 to 0.60 molybdenum, and 0.3 maximum silicon. Nitralloy is marketed by various steel companies. Nitrard is also the name of a nitriding steel. Nitralloy steel is used for tools, gages, gears, and shafts. Unlike the soft core of ordinary case-hardened steels, it will have a tough core with high hardness. Nitralloy 135 contains 0.35% carbon, 0.55 man- ganese, 0.30 silicon, 1.20 copper, 1 aluminum, and 0.20 molybdenum, and has a tensile strength, hardened, of 138,000 lb/in 2 (952 MPa) with elongation of 20% and Brinell hardness of 280. Nitralloy N is similar but with about 3.5% nickel, higher chromium, and less car- bon, providing a Brinell hardness of 415. Carbonitrided steel is produced by exposing the steel at about 1500°F (816°C) in a carbon-nitrogen atmosphere and then quenching in oil. The depth of the case depends on the length of time of treat- ment. The surface is harder and more wear-resistant than carbon case-hardened steel. NITROCELLULOSE. A compound made by treating cellulose with nitric acid, using sulfuric acid as a catalyst. Since cotton is almost pure cellulose, it was originally the raw material used, but alpha cel- lulose made from wood is now employed. The cellulose molecule will unite with from one to six molecules of nitric acid. Trinitrocellulose, C 12 H 17 O 7 (NO 3 ) 3 , contains 9.13% nitrogen and is the product used for plastics, lacquers, adhesives, and Celluloid. It is classified as cellulose nitrate. The higher nitrates, or pyrocellulose, are employed for making explosives. Dry nitrocellulose explodes with a detonation velocity of 4.5 miles/s (7.3 km/s), so it is always stored in a humid state. It was originally called guncotton, and the original U.S. gov- ernment name for the explosive was Indurite, from the Indian Head Naval Powder Factory. It was called cordite in England. The nitrated cellulose is mixed with alcohol and ether, kneaded into a dough, and squeezed through orifices into long, multitubular strings NITROCELLULOSE 641 Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Materials, Their Properties and Uses which are cut into short, cylindrical grains. Solid grains become smaller as they burn, so that there would be high initial pressure and then a decreasing pressure of gases. When the multitubular grains burn, the surface becomes greater, and thus there is increasing pres- sure. FNH powder, or flashless powder, is nitrocellulose which is nonhygroscopic and which contains a partially inert coolant, such as potassium sulfate, to reduce the muzzle flash of the gun. Ballistite is a rapid-burning, double-base powder used in shotgun shells and as a propellant in rockets. It is composed of 60% nitrocellulose and 40 nitroglycerin, made into square flakes 0.005 in (0.013 cm) thick or extruded in cruciform blocks. NITROGEN. An element, symbol N, which at ordinary temperatures is an odorless and colorless gas. The atmosphere contains 78% nitrogen in the free state. It is nonpoisonous and does not support combustion. Nitrogen is often called an inert gas, and is used for some inert atmospheres for metal treating and in lightbulbs to pre- vent arcing, but it is not chemically inert. It is a necessary element in animal and plant life and is a constituent of many useful com- pounds. Lightning forms small amounts of nitric oxide from the air which is converted to nitric acid and nitrates, and bacteria continu- ously convert atmospheric nitrogen to nitrates. Nitrogen combines with many metals to form hard nitrides useful as wear-resistant metals. Small amounts of nitrogen in steels inhibit grain growth at high temperatures and increase the strength of some steels. It is also used to produce a hard surface on steels. Nitrogen has five iso- topes, and nitrogen 15 is produced in enrichments to 95% for use as a tracer. Most of the industrial use of nitrogen is through the medium of nitric acid, obtained from natural nitrates or from the atmosphere. Fixation of nitrogen is a term applied to any process whereby nitro- gen from the air is transferred into nitrogen compounds, or fixed nitrogen, such as nitric acid or ammonia. The first step is by pass- ing air through an electric arc to produce nitric oxide, NO, a heavy, colorless gas, which oxidizes easily to form nitrogen dioxide, NO 2 , a brown gas with a disagreeable odor. This oxide reacts with water to form nitric acid. Or, atmospheric nitrogen can be converted to the oxide by irradiation of the compressed heated air with uranium oxide. Vast quantities of nitrogen are reacted with hydrogen to make ammonia fertilizers. Nitrogen for these applications is obtained by liquefaction of air. A recent method is to separate air into its con- stituents by using polymeric membranes. Permea, Inc. separates air by using membranes, as do Generon Systems, and Air Products and Chemicals. In the Kryoclean process, nitrogen is used to remove volatile organic compounds (VOCs) from process emissions. The 642 NITROGEN Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Materials, Their Properties and Uses emissions are taken in a gaseous nitrogen stream to condensers where liquid nitrogen cools the stream to a temperature at which the VOCs condense. The liquefied VOCs are then recovered. Nitrogen is used to stimulate tertiary oil wells. Nitrogen gas is used in plasma- arc and laser cutting and as a shielding gas in welding. Calcium cyanamide, CaCN 2 , made by reacting atmospheric nitrogen with calcium carbide, is used as a fertilizer and as a chemical raw mater- ial. The chemical radical cyanamid, or hydrogen cyanamide, H 2 N и C и N, is marketed as a stable, colorless 50% aqueous concen- trate. The nitrogen-containing gas Drycolene, of General Electric Co., used for furnace atmospheres for sintering metals, contains 78% N 2 , 20 CO, and 2 H 2 . It is produced by burning hydrocarbon gases and air, removing the moisture, and passing through incandescent charcoal to convert the CO 2 and residual moisture to CO and H 2 . Nitrogen liquefies at about Ϫ319°F (Ϫ195°C) and solidifies at about Ϫ346°F (Ϫ210°C). Nitrogen gas occupies 696 times as much space as the liquid nitrogen used in surgery. Cryogenic cooling with liquid nitrogen speeds extrusion and improves the quality of polyolefin pipe. Liquid-nitrogen–based atmospheres, such as blends of nitrogen-hydrogen and nitrogen-methanol, are used for brazing. Purifire-BR atmosphere systems, of Air Products, are low- cost alternatives for brazing carbon steel. They are used to produce gas atmospheres from on-site, noncryogenically generated nitrogen and nat- ural gas, using a proprietary purification system. Brazed parts exhibit good braze flow, surface appearance, and joint strength. Nitrogen gas derived from the liquid gas eliminates sparks in soldering electronic components and acts as a safety curtain at the entrance and exit of hydrogen-atmosphere furnaces. Nitrogen gas is used as a blanket over volatile liquids in vapor-recovery systems to prevent emission of haz- ardous vapors in process vessels into the atmosphere during storage, handling, and processing. The gas reduces the oxygen content in the vapor space above the liquid, reducing fire and explosion hazards and preventing air, moisture, and other contaminants from entering. By maintaining a constant pressure in the vapor space, the vessels can breathe during pumping operations and during ambient temperature changes that cause the liquid to contract or expand. Nitrogen oxide and nitrogen dioxide generated by the combustion of fossil fuels are air pollutants, contributing to the formation of ozone, or photochemical smog, and acid rain. Thus, regulations limiting their emission have been instituted. These nitrogen oxides, or NO x compounds, can be reduced to nitrogen and water by selective cat- alytic reduction. This involves injecting ammonia into the flue gas of heaters, boilers, gas-turbine systems, and coal-fired steam plants, then passing the gas through a reactor housing the catalysts. NITROGEN 643 Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Materials, Their Properties and Uses NITROGLYCERIN. A heavy, oily liquid known chemically as glyceryl trinitrate and having the empirical formula C 3 H 5 (NO 3 ) 3 . It is made by the action of mixed acid (90% nitric and 25 to 30 oleum) on very pure glycerol in the presence of sulfuric acid. It is highly explosive, detonating upon concussion. Liquid nitroglycerin when exploded forms carbonic acid, CO 2 , water vapor, nitrogen, and oxygen; 1 lb (0.45 kg) is converted into 156.7 ft 3 (4.4 m 3 ) of gas. The temperature of explosion is about 628°F (330°C). For use as a commercial explosive it is mixed with absorbents, usually kieselguhr or wood flour, under the name of dynamite. Cartridges of high density explode with greater shattering effect than those of low density. By varying the density and the mixture of the nitroglycerin with ammonium nitrate, which gives a heaving action, a great diversity in properties can be obtained. Ethylene glycol dinitrate (nitroglycol) and diethylene glycol dinitrate are also explosives. They are generally used to plas- ticize nitrocellulose. Dynamites are rated on the percentage, by weight, of nitroglyc- erin that they contain. A 25% dynamite has 25% by weight of nitro- glycerin and a rate of detonation of 11,800 ft/s (3,597 m/s). The regular grades contain from 25 to 60%. Ditching dynamite is the 50% grade. It has a rate of detonation of 17,400 ft/s (5,304 m/s), and will detonate sympathetically from charge to charge along a ditch line. Extra dynamite has half of the nitroglycerin replaced by ammonium nitrate. It is not so quick and shattering, and not as water-resistant, but is lower in cost. It is used for quarrying, stump and boulder blasting, and highway work. A 50% extra dynamite has a detonation rate of 10,800 ft/s (3,292 m/s). Hercomite and Hercotol are extra dynamites of Hercules, Inc., while Durox is an ammonium dynamite of Du Pont, and Agritol, a low-velocity dyna- mite also of Du Pont, is a low-density ammonium dynamite for stump blasting. Gelatin dynamite is made by dissolving a special grade of nitro- cotton in nitroglycerin. It has less fumes, it is more water-resistant, and its plasticity makes it more adaptable for loading solidly in holes for underground work. It is marketed as straight gelatin or as ammo- nium gelatin, called gelatin extra. The gelatin dynamites come in grades from 20 to 90%. All have a detonation rate of 8,500 ft/s (2,591 m/s), but modified high-pressure gelatin has rates to 19,700 ft/s (6,005 m/s). These, however, produce large amounts of fumes and are not for use in mines or confined spaces. Blasting gelatin, called oil-well explosive, is a 100% dense and waterproof gelatin with the appearance of crude rubber and having a detonation rate of 8,500 ft/s (2,591 m/s). Gelamite and Hercogel are gelatin blasting dyna- mites of Hercules, Inc., although Bituminite, of this company, is a 644 NITROGLYCERIN Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Materials, Their Properties and Uses slow permissible ammonium nitrate dynamite for coal mines. Gelobel is a gelatin dynamite, and Monobel is an ammonium dyna- mite marketed by Du Pont for mine blasting. The Gelodyn explo- sive of Atlas Powder Co. is a combination of ammonium gelatin dynamite that is plastic, gives a shattering effect, and does not pro- duce excessive fumes. It is used for construction blasting. Amocol, of this company, is a blasting explosive composed of grained ammonium nitrate mixed with ground coal. The double-base solid propellant for rockets, known as ballistite, is nitroglycerin-nitrocellulose. With potassium perchlorate as an oxidizer, it gives a specific impulse of 180 to 195. It leaves plumes of white smoke. Dynamite is also sometimes used for explosive metal forming, as it releases energy at a constant rate regardless of confinement, and produces pressures to 2 ϫ 10 6 lb/in 2 (1,379 MPa). For bonding metal laminates, a thin sheet, or film, of the explosive is placed on top of the composite, and the pro- gressive burning of the explosive across the film produces an explo- sive force downward and in vectors that produces a microscopic wave, or ripple, in the alloyed bond that strengthens the bond but is not vis- ible on the laminated sheet. NONMAGNETIC STEEL. Steel and iron alloys used where magnetic effects cannot be tolerated. Manganese steel containing 14% man- ganese is nonmagnetic and casts readily but is not machinable. Nickel steels and iron-nickel alloys containing high nickel are also nonmagnetic. Many mills regularly produce nonmagnetic steels containing from 20 to 30% nickel. Manganese-nickel steels and manganese-nickel-chromium steels are nonmagnetic and may be formulated to combine desirable features of the nickel and man- ganese steels. One nonmagnetic steel with a composition of 10.5 to 12.5% manganese, 7 to 8 nickel, and 0.25 to 0.40 carbon has low magnetic permeability and low eddy-current loss, can be machined readily, and work-hardens only slightly. The tensile strength is 80,000 to 110,000 lb/in 2 (552 to 758 MPa), elongation 25 to 50%, and specific gravity 8.02. It is austenitic and cannot be hardened. The 18–8 austenitic chromium-nickel steels are also nonmagnetic. A non- magnetic alloy used for watch gears and escapement wheels is not a steel but is a copper-nickel-manganese alloy containing 60% cop- per, 20 nickel, and 20 manganese. It is very hard, but can be machined with diamond tools. NONSHATTERING GLASS. Also referred to as shatterproof glass, laminated glass, or safety glass, and when used in armored cars, it is known as bulletproof glass. A material composed of two sheets of plate glass with a sheet of transparent resinoid between, the whole NONSHATTERING GLASS 645 Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Materials, Their Properties and Uses molded together under heat and pressure. When subjected to a severe blow, it will crack without shattering. The first of these was a German product marketed under the name of Kinonglas, which con- sisted of two clear glass plates with a cellulose nitrate sheet between, and it was first used for protective shields against chips from machines. Nonshattering glass is now largely used for automobile and car windows. The original cellulose nitrate interlining sheets had the disadvantage that they were not stable to light and became cloudy. Cellulose acetate was later substituted. It is opaque to actinic rays and prevents sunstroke but has the disadvantage of opening in cold weather, permitting moisture to enter between the layers. The acrylic resins are notable for their stability in this use; in some cases they are used alone without the plate glass, especially for aircraft windows. Polyvinyl acetal resins, as interlinings for safety glass, are weather-resistant and will not discolor. Polyvinyl butyral is much used as an interlayer, but in airplane glass at about 150°F (66°C) it tends to bubble and ripple. Silicone resins used for this purpose with- stand heat to 350°F (177°C), and they are not brittle at subzero tem- peratures. Silastic Type K, of Dow Chemical Co., is such a silicone resin used as an interlayer. Flexseal, of PPG Industries, is a lami- nated plate glass with a vinyl resin interplate with an extension for sealing into the window frame. It withstands a pressure of 20 lb/in 2 (0.14 MPa), with a 0.125-in (0.32-cm) plastic interplate, and is used for aircraft windows. Duplate is the trade name of Duplate Canada Inc. for a nonshattering glass. Standard bulletproof glass is from 1.5 in (3.81 cm), 3 ply, to 6 in, 5 or more ply. NONWOVEN FABRIC. In the most general sense, fibrous-sheet materi- als consisting of fibers mechanically bonded together by interlocking or entanglement, by fusion, or by an adhesive. They are characterized by the absence of any patterned interlooping or interlacing of the yarns. In the textile trade, the terms nonwovens and bonded fab- rics are applied to fabrics composed of a fibrous web held together by a bonding agent, as distinguished from felts, in which the fibers are interlocked mechanically without the use of a bonding agent. There are three major kinds of nonwovens based on the method of manufac- ture. Dry-laid nonwovens are produced by textile machines. The web of fibers is formed by mechanical or air-laying techniques, and bonding is accomplished by fusion-bonding the fibers or by the use of adhesives or needle punching. Either natural or synthetic fibers, usu- ally 1 to 3 in (2.5 to 7.6 cm) in length, are used. Wet-laid nonwo- vens are made on modified papermaking equipment. Either synthetic fibers or combinations of synthetic fibers and wood pulp can be used. The fibers are often much shorter than those used in dry-laid fabrics, 646 NONWOVEN FABRIC Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Materials, Their Properties and Uses ranging from 0.25 to 0.5 in (0.64 to 1.27 cm). Bonding is usually accomplished by a fibrous binder or an adhesive. Wet-laid nonwovens can also be produced as composites, for example, tissue-paper lami- nates bonded to a reinforcing substrate of scrim. Spin-bonded non- wovens are produced by allowing the filaments emerging from the fiber-producing extruder to form into a random web, which is then usually thermally bonded. These nonwovens are limited commercially to thermoplastic synthetics such as nylons, polyesters, and poly- olefins. They have exceptional strength because the filaments are continuous and bonded to each other without an auxiliary bonding agent. Fibers in nonwovens can be arranged in a great variety of con- figurations that are basically variations of three patterns: parallel or unidirectional, crossed, and random. The parallel pattern provides maximum strength in the direction of fiber alignment, but relatively low strength in other directions. Cross-laid patterns (like wovens) have maximum strength in the directions of the fiber alignments and less strength in other directions. Random nonwovens have relatively uniform strength in all directions. NUTMEG. The brown, round, wrinkled seed of the plumlike fruit of the evergreen tree Myristica fragrans, native to the Moluccas but now grown extensively also in Grenada. The bright-red aril covering of the seed is called mace. The trees average about 20 lb (9 kg) of kernels per year, but a large tree may bear as many as 10,000 nut- megs annually. The average yield in Grenada is taken as 1,500 lb (680 kg) of green nutmegs per acre (4,047 m 2 ) per year, giving 720 lb (327 kg) of dry sound nutmegs and 150 lb (68 kg) of mace per acre (4,047 m 2 ). The nutmeg tree grows best on tropical islands at a height of 500 to 1,500 ft (152 to 457 m) above sea level. It begins to bear at 6 years, and will bear for a century. The ripe fruit splits, and the seeds fall to the ground. Nutmeg is a delicately flavored spice for foodstuffs, but in large amounts is highly toxic. Mace has a finer but weaker flavor and is used as a savory, but oleoresin mace of Fritzsche Dodge & Olcott Inc., a dark-brown liquid produced from mace, gives a lasting spicy nutmeg flavor and is used as a substitute for nutmeg oil. Nutmeg butter is a solid yellow fat obtained from the rejected nutmegs of the spice trade. To obtain the fat, the kernels are roasted and ground before extraction. The nutmeg contains about 40% of the fat. It is used chiefly in ointments. Nutmeg oil is an essential oil extracted from nutmeg and used in medicine, flavoring tobacco, and dentifrices. It is also called myristica oil and is high in myristicin, a yellow poisonous oil of composition C 3 H 5 и C 6 H 2 (O 2 CH 2 )OCH 3 . It is now synthesized from pine oil. NUTMEG 647 Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Materials, Their Properties and Uses NUX VOMICA. The seeds of the ripe fruit of the deciduous tree Strychnos nux vomica of India, Ceylon, and Australia, used as the source of the alkaloids strychnine and brucine. The powdered seed may also be used. The fruits contain three to five hard, grayish seeds which yield 1 to 1.25% strychnine alkaloid and about the same amount of brucine. Strychnine is an odorless, crystalline, intensely bitter powder of composition C 21 H 22 N 2 O 2 with a very complex multi- ring molecular structure. It is a spinal stimulant and in quantity is a violent convulsive poison. It is used in proprietary and prescription medicines of the tonic class, and in rat poisons. For medicinal use it is employed mostly in the form of strychnine sulfate which is easily solu- ble in water. Brucine is a bitter, crystalline alkaloid of composition C 23 H 26 N 2 O 4 with similar characteristics but much less active. It is dimethoxystrychnine. It is also used as a denaturant for rapeseed oil and other industrial oils. The woody vine woorali, S. toxifera, of the Amazon and Orinoco valleys, from which the arrow poison curare was obtained, contains strychnine and curine, a benzyl isoquinoline alkaloid. Curare inactivates the motor nerves without affecting the sensory and central nervous system and is used in medicine as a local anesthetic. The synthetic Mytolon is used as a more potent and safer substitute. It is a complex diethylaminopropylaminobenzoquinone benzyl chloride in the form of red crystals. NYLON. A group of polyamide resins which are long-chain poly- meric amides in which the amide groups form an integral part of the main polymer chain, and which have the characteristic that when formed into a filament, the structural elements are oriented in the direction of the axis. Nylon was originally developed as a tex- tile fiber, and high tensile strengths, above 50,000 lb/in 2 (345 MPa), are obtainable in the fibers and films. But this high strength is not obtained in the molded or extruded resins because of the lack of ori- ented stretching. When nylon powder that has been precipitated from solution is pressed and sintered, the parts have high crys- tallinity and very high compressive strength, but they are not as tough as molded nylon. Nylons are produced from the polymeriza- tion of a dibasic acid and a diamine. The most common one of the group is that obtained by the reaction of adipic acid with hexameth- ylenediamine. Nylons are often designated by the number of carbon atoms in their feedstock monomer: six for caprolactam, the feedstock for Nylon 6, and 12 for laurolactam, the feedstock for Nylon 12, for example. Dual-number designations, such as 6.6 and 6.12 refer to nylons polymerized from diamines and diacids, the first numeral pertaining to the amount of carbon atoms or the diamine, the sec- 648 NUX VOMICA Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Materials, Their Properties and Uses ond to those in the diacid. Further, a period is used between numer- als of homopolymers and a slash sign between those of copolymers. Thus, Nylon 6.12 is a homopolymer and 6/12 is a copolymer. The greater the number of carbon atoms, the lower the nylon’s specific gravity and melting point and the less its moisture absorption. Nylon 6 and 6.6 differ in crystalline structure and melting point—420°F (216°C) and 490°F (254°C)—but are similar in most mechanical properties. All of the nylons are highly resistant to common solvents and to alkalies, but are attacked by strong mineral acids. Molded parts have light weight, with a specific gravity of about 1.14, good shock-absorb- ing ability, good abrasion resistance, very low coefficient of friction, and high melting point, up to about 482°F (250°C). A disadvantage is their high water absorption and the resulting dimensional changes in moldings in service. They are much used for such parts as gears, bearings, cams, and linkages. The electrical characteristics are about the same as those of the cellulosic plastics. As a wire insulation, nylon is valued for its toughness and solvent resistance. Nylon fibers are strong, tough, and elastic and have high gloss. The finer fibers are easily spun into yarns for weaving or knitting either alone or in blends with other fibers, and they can be crimped and heat-set. For making carpets, nylon staple fiber, lofted or wrinkled, is used to give the carpet a bulky texture resembling wool. Tire cord, made from Nylon 6 of high molecular weight, has the yarn drawn to 4 or 5 times its original length to orient the polymer and give one-half twist per inch. Nylon film is made in thicknesses down to 0.002 in (0.005 cm) for heat-sealed wrapping, especially for food products where tight, impermeable enclosures are needed. Nylon sheet, for gaskets and laminated facings, comes transparent or in colors in thicknesses from 0.005 to 0.060 in (0.013 to 0.152 cm). Nylon monofilament is used for brushes, surgical sutures, tennis strings, and fishing lines. Filament and fiber, when stretched, have a low specific gravity down to 1.068, and the tensile strength may be well above 50,000 lb/in 2 (345 MPa). Nylon fibers made by condensation with oxalic esters have high resistance to fatigue when wet. Nylon 6 molded parts have a tensile strength of 11,700 lb/in 2 (79 MPa), elongation 70% and a dielectric strength of 440 V/mil (17.3 ϫ 10 6 V/m. Nylon foam, or cellular nylon, for lightweight buoys and flotation products, is made from Nylon 6. The foam is produced by Du Pont in slabs, rods, and sheets. Density ranges from 1 to 8 lb/ft 3 (16 to 128 kg/m 3 ). The low-density types are flexible, but the high-density material is rigid with a load-carrying capacity about the same as that of balsa wood. Ultramid A3HG7, a glass-fiber-reinforced Nylon 6/6 of BASF, and Du Pont’s Zytel 6/6 are used for auto engine air-intake NYLON 649 Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Materials, Their Properties and Uses [...]... blown are rapeseed, cottonseed, linseed, fish, and whale oils The blown fish oils of ArcherDaniels-Midland Co., used for paints, enamels, and printing inks, are preoxidized and destearinized, and have specific gravities from 0 .98 0 to 1.025 Crystol oils, of this company, are kettle-boiled fish oils for paints A fine-grained, slaty silica rock for sharpening edged tools The bluish-white and opaque white... and habit-forming The English drug Heptalgin is a similar morphine substitute Poppy-seed oil is a colorless to reddish-yellow liquid of specific gravity of about 0 .92 5 and iodine number 157 used as a drying oil in artists’ varnishes The cold-pressed white oil is used locally as an edible oil The very dark grades are used in soaps and in paints The oil from the seed does not contain opium A metal-bearing... oleic acid, yellow and red, are known as distilled red oil and saponified They may be sold under trade names Alcholein 810 is a clear, distilled red oil used for textile treating Monoenoic acid is a modified isomer of oleic acid which produces soaps that are nonirritating to skin It is used in cosmetics Hydrofol C-18, of Archer-Daniels-Midland Co., is this acid Aluminum oleate is used for thickening lubricating.. .Materials, Their Properties and Uses 650 NYLON manifolds for weight reduction over cast aluminum designs Zytel FE82 09 is a toughened semiconductive grade for dissipation of static electricity Nylatron GS-51, of DSM Engineering Plastics, is a glass-reinforced and molybdenum-disulfide-filled Nylon 6/6 used for auto engine valve-lifter guides Lubriloys, of LNP Engineering Plastics, are lubricated 6/6... Oatmeal paper, used chiefly for wallpaper, has a flaky finish produced by washing a solution of wood flour over the sheet on the forming wire in the paper machine The wood flour may be natural or dyed Cartridge paper is 5 0- to 80-lb (2 3- to 36-kg) Manila paper, waxed on one side, originally used for muzzle-loading cartridges, but now employed where a stiff, waterproof material is needed Glassine is a... called novaculite, and they received their name because they were originally used for razor sharpening They are composed of 99 .5% chalcedony silica and are very hard with a fine grain Novaculite is a deposit from hot springs It is fine-grained, and the ordinary grades are employed for the production of silica refractories Arkansas oilstones are either hard or soft and have a waxy luster They are shipped... “palladium-only” catalyst developed by Allied Signal can reduce precious-metal cost by excluding platinum and rhodium An oil obtained from the fleshy covering of the seed nuts of several species of palm trees, chiefly Elaeis guineensis, native to PALM OIL Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies All rights reserved... limestone obtained from stalactites in caves These materials are cut into such articles as lamp stands Argentine onyx is a dark-green or a green-yellow, translucent stone of great decorative beauty In the United States it is called Brazilian onyx and is used for bookends, lamp bases, inkstands, and ornaments Opalized wood is an onyxlike petrified wood from Idaho It is cut into ornaments Materials used in ceramic... 22.65, and a high melting point, 4 890 °F (2 698 °C) The boiling point is about 99 00°F (5468°C) Osmium has a close-packed hexagonal crystal structure, and it forms solid-solution alloys with platinum, having more than double the hardening power of iridium in platinum However, it is seldom used to replace iridium as a hardener except for fountain-pen tips where the alloy is called osmiridium The name osmium... passes through water Water-borne paints consist essentially of finely divided ingredients, including plastic resins, fillers, and pigments, suspended in water An organic medium may also be involved There are three types of water-borne coatings: emulsion coatings or latexes, dispersion coatings, and water-soluble coatings Emulsions, or latexes, are aqueous dispersions of high-molecular-weight resins Strictly . gas-turbine systems, and coal-fired steam plants, then passing the gas through a reactor housing the catalysts. NITROGEN 643 Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright. much shorter than those used in dry-laid fabrics, 646 NONWOVEN FABRIC Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill. are used for auto engine air-intake NYLON 6 49 Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies. All rights