bluuebunny/crossref_metadata_2025 huggingface dataset:
Ethylene
Authors: Sundaram K. M. , Shreehan M. M. , Olszewski E. F.
Published: July 2004

In this comprehensive discussion of the production of and uses for ethylene, the topics covered include the properties of ethylene; industrial production; storage, shipping, handling; and economics. Extensive coverage of the commercial production of ethylene via thermal cracking is provided. The reaction is discussed as well as the methods employed to predict the feedstock conversion. Product distributions are given for a variety of feedstocks. A description of the industrial furnaces available is given, as well as a typical process description and process flow diagram. Information is provided on coke deposition during the cracking process, giving the methods used to inhibit coke production and methods used to remove coke deposited. Improvements in the design of ethylene plants plus possible other routes to produce ethylene are presented. Almost all ethylene is consumed as a feedstock for manufacturing other petrochemicals.
Evaporation
Authors: Standiford Ferris C.
Published: July 2004

Evaporation is used most often in the chemical industry for concentrating a solution or crystallizing a solid from solution. The high latent heat of the solvent (usually water) generally makes heat transfer the most important element of evaporator design and capital cost. Heat‐transfer surfaces usually are metal tubes and many configurations are available to improve performance, the choice depending primarily on the characteristics of the material being processed and the scale of the operation. The high heat demand of evaporators makes energy consumption the most important element of operating cost. Means available for reducing energy demand include multiple‐effect or multistage flash operation and vapor recompression, where the vapor given off by an evaporator is compressed so that it can serve as part or all of its own heating medium. Other important factors in evaporator selection and design are the separation of vapor from the residual liquid to the degree necessary in each case and the provision of a heat sink for the large amount of energy utilized.
Exhaust Control, Industrial
Authors: Berglund Ronald L.
Published: July 2004

Exhaust emissions are increasingly legislated. Much of the research and development in the chemical process, petroleum, power generation, and manufacturing industries is driven by the need to control exhausts utilizing post‐process emissions treatment. Oxidative combustion technology is commonly employed for elimination of volatile organic components. This technology may be strictly thermal (incineration) or employ oxidation catalysis. The catalysts, mechanistic models, and design, operation, and selection of industrial catalytic exhaust control systems are discussed, as is catalytic inhibition. Exhaust control technology for criteria air pollutants, such as the nitrogen oxides, is presented. The use of catalytic oxidation techniques for control of specific emissions within particular industries is also discussed.
Metallic Coatings Explosively Clad Metals
Authors: Bergmann Oswald R.
Published: July 2004

Explosion bonding of metals is a mature and reliable manufacturing process for the production of high quality, metallurgically bonded metal combinations that are difficult or impossible to produce by conventional metal bonding techniques. In explosion bonding the actual process of metal bonding occurs over extremely short time periods. Explosives are used, and there is no significant overall heating of the metals being bonded. From a metallurgical standpoint the process may be characterized as a diffusionless, cold‐pressure bonding technique involving localized, extremely short‐time, plastic deformation of the metals near the bond zone. The process is used by several manufacturers throughout the world to produce clad plate and sheet for corrosion‐resistant chemical‐process vessels, for heat‐exchanger tube sheets, electrical and structural weld‐transition joints and several other specialized applications. Process fundamentals and mechanisms are described along with a summary of practical operating parameters. Numerous industrial applications are described.
Explosives
Authors: Lindner Victor
Published: July 2004

The explosive phenomena that characterize detonation are described as well as their safety, environmental, and demilitarization‐disposal aspects. Descriptions of current methods of manufacture and the physical and chemical properties of the most important primary and secondary explosives are included. Also discussed are industrial explosives and high energy and insensitive explosives.
Fat Replacers
Authors: Morse Roy E. , Singer Norman
Published: July 2004

Significant interest in reducing dietary fat from 40% of dietary calories to below 30% is being driven by two thrusts, ie, health problems and cosmetic weight loss. Fat substitutes under study include starches, gums, other complex carbohydrates, and microparticulate proteins. Replacement of fats requires mixtures rather than single substances.
Ferroelectrics
Authors: Jang Sei‐Joo
Published: July 2004

Ferroelectric materials are nonlinear dielectrics that can exhibit a spontaneous polarization in the absence of an external electric field. Reorientation of the domain‐state polarization by an external field is the defining characteristic. An important class of ferroelectrics is that of the perovskites. Modified barium titanate and lead zirconate‐lead titanate solid solution‐based ceramics are the most extensively used materials for multilayer capacitors and piezoelectric devices, respectively. Relaxor ferroelectrics arising from the lead‐magnesium niobates are gaining in usage, and ferroelectric thin films are under development. Ferroelectrics are utilized in various polymer‐matrix composite materials in the automotive, imaging, and telecommunications industries.
Recycling, Ferrous Metals
Authors: Makar Harry V.
Published: July 2004

Makar, Harry V. (Consultant). Ferrous scrap recycling is a principal worldwide activity. Annual consumption and exports in the United States total ∼80 million metric tons. The primary consumers of ferrous scrap are steel mills and iron and steel foundries. These depend on scrap for a large fraction of their iron‐based raw materials. The steel industry consumes about 75% and iron and steel foundries consume most of the rest.

The several sources and types or grades of ferrous scrap are presented including descriptions of supply, demand, exports, and prices. Concerns about residual elements from both environmental and product quality point of view are discussed. Standards and environmental regulations are reported. Recycling of ferrous scrap is dependent on iron and steel industry processes and demands. Low residual scrap is preferred. Vol. 20, pp. 1092–1106, 37 refs. to June 1995.
Fillers
Authors: Tsou Andy H. , Waddell Walter H.
Published: July 2004

Fillers are particulate materials added to polymers in order to improve the physical properties and/or to reduce the cost of the composite. They can be classified according to their source, function, composition, and/or morphology. No single classification scheme is entirely adequate due to the overlap and ambiguity of these categories. The chemical composition and its effect on composite physical properties typically classify fillers into three broad categories: nonreinforcing or degrading, semireinforcing or extending, and reinforcing fillers. Use of fillers in many commerical polymers is for the enhancement in stiffness, strength, dimensional stability, toughness, heat distortion temperature, damping, impermeability, and cost reduction, although not all of these desirable features are found in any single filled polymer. Improvements in composite physical properties is directly related to particle size, whereby the smaller particulate fillers impart greater reinforcement. Particle‐size distribution and particle shape also have significant effects on composite reinforcement. Filler structure ranges from precise geometrical forms, such as spheres, hexagonal plates, or short fibers, to irregular masses. A particle with a high aspect ratio has higher reinforcement than a more spherical one. Fillers having a broad particle‐size distribution have better packing in the polymer matrix and provide lower viscosity than that provided by an equal volume of the filler with a narrow particle‐size distribution. The properties of particulate‐filled polymers are determined by the properties of the components, by the shape of the filler phase, by the morphology of the system, and by the polymer‐filler interfacial interactions.
Film and Sheeting Materials
Authors: Mackenzie K. J.
Published: July 2004

Plastic film and sheet products represent a significant use for polymeric resins of all types. Film and sheet products serve a wide range of consumer, commercial, and industrial markets, including packaging, communication materials (magnetic tape, reprographic and photographic products, and stationery), thermal and electrical insulation, optical products (glazing, filters, and light control), agricultural mulching, and construction, as well as for component manufacture in appliances, transportation equipment, and electrical equipment. The principal film and sheet resins are the polyolefins (polyethylene and polypropylene), polystyrene, the vinyl resins, polyesters, and the cellulosics. Specialty markets, in smaller volume, exist for film and sheet products made from higher cost or high performance polymers.

Film properties may vary from strong, stiff materials to soft, pliable, even rubbery films. Sheet may be hard and rigid or soft foams. Properties such as tensile, impact, and tear strength can be obtained over a wide range, dependent on the polymer used, the presence of additives or modifiers, and the process used in their manufacture. Similarly, variations in slip, handleability, sealability, optical properties, electrical properties, and color or transparency can be altered to meet end use requirements.

Films and sheet are commonly manufactured by such melt‐extrusion processes as flat die extrusion, blown tube extrusion, and calendering, or by solution casting. Other processes include reactive casting of sheet or the regeneration of cellulose. Auxiliary processes used in film or sheet manufacture include coextrusion of multilayers, coating, laminating, and orientation (monoaxial or biaxial).
Fine Art Examination and Conservation
Authors: van Zelst Lambertus
Published: July 2004

Chemical and physical methodologies are applied in the study of museum objects for a variety of purposes including the establishment of authenticity, scholarly pursuits in art history and archaeology, and evaluation of the state of preservation. Objects may be composites or formed from relatively pure materials. The technological history for object types and materials and the methodologies most frequently used for their analysis and examination is summarized. Metals, ceramics, stone, and plant and animal materials are commonly encountered. An overview of materials properties is provided. Conservation science as a type of materials science research seeks to understand the processes involved in long‐term materials degradation, and from this understanding to formulate conditions for storage and exhibit most conducive to optimal preservation. Methods for preservation of metals, stone, and wooden objects are discussed.
Textiles, Finishing
Authors: Calamari Timothy A. , Harper Robert J.
Published: July 2004

Textile finishing includes various efforts to improve the properties of textile fabrics, whether for apparel, home, or other end uses. These processes are directed toward modifying either the fiber characteristics or the gross textile end properties. The advent of synthetic fibers possessing improved resiliency and dimensional stability has placed natural fibers, particularly cotton, at an ostensible disadvantage, putting pressure on cotton interests to focus on the perceived deficiencies of natural fibers. This article discusses fabric preparation, different finishing methods and their applications, the mechanism and use of cross‐linking agents, as well as such topics as dyeing modifications and finishing of synthetic fibers.
Flavor Characterization
Authors: Acree Terry E.
Published: July 2004

Flavor is a chemosensory response to chemicals in food, and its characterization involves both chemical characterization of the sensory‐active components in food and a description of the sensory response to food. Even though a complex series of biochemical, physiological, and mental processes take place between the stimulation by flavorants and the behavioral responses to flavorants, the process of flavor characterization only requires a measure of the inputs and outputs, ie, chemicals and sensory responses. Flavors are first characterized with bioassays that quantitatively relate flavor activity with separate components, then the chemicals that cause flavor can be characterized by instrumental procedures such as chromatography and spectroscopy. The complexity and variability of the sensory responses to flavor by individuals or groups of individuals can be measured by a set of formal methods called sensory tests. Sensory tests are often conducted without any chemical information on the flavorants involved. This article outlines some of the general considerations involved in flavor characterization along with several specific examples of the most common techniques.
Flavor Delivery Systems
Authors: Ubbink Job , Schoonman Annemarie
Published: July 2004

An overview is given of flavor delivery systems and technologies for flavor encapsulation. A central conceptual distinction made is between systems aimed at protecting the encapsulated flavor against evaporation and the adverse effects of environmental oxygen in low‐moisture states, and those whose principal aim is to modify the release of the encapsulated flavor during food processing, storage, or consumption. The former class of systems, which are designated as glass‐encapsulation systems since they are invariably based on amorphous carbohydrates in the glassy state, are generally prepared by well‐established technologies like spray drying and melt extrusion. These systems have found widespread commercial application. Accounts are given of the most‐used technologies and of the underlying material science. The latter class of systems, principally aimed at controlling the release rate of the encapsulated flavor, is far more diverse in composition, working principle, and manufacturing technology. Their common feature is that, in the food matrix, they retain a core structure whose role is to control both the rate and the extent of release of the encapsulated flavor. It is argued that application of such systems necessitates a careful tuning of the delivery system to both the specific composition of the flavor, the composition and structure of the food matrix and the conditions during food processing, storage and consumption, because of the comparatively well‐defined release aimed for. Several of the principal technologies are highlighted. Examples are given of successful applications in food matrices. It is conjectured that limitations currently experienced in the application of controlled release systems for flavors and that impede a truly widespread adoption in the food industry can only be eliminated by a concerted approach including encapsulation technology, flavor physico‐chemistry and chemistry, food materials science, and focused product development efforts.
Flow Measurement
Authors: Burgess Thomas H.
Published: July 2004

Flow measurement is essential to the production, distribution, consumption, and disposal of all liquids and gases including fuels, chemicals, foods, and wastes. Emphasis is placed on the types of measuring equipment and the general selection criteria. Fluid properties of the ambient environment, particular measurement requirements, and economics all influence the choice of flow meters.

The various measurement methods and corresponding hardware are discussed in terms of principles of operation, variations in available forms, advantages and limitations, and commonly used areas of application. Flow meters can be classified according to whether the signal employed is generated by the energy of the flowing fluid or derived from the interaction of the fluid motion with some external stimulus. The first group is composed primarily, but not completely, of mechanical meters whereas the second is electrical in nature.
Fluid Mechanics
Authors: Son J. S.
Published: July 2004

Fluid mechanics encompasses both the phenomena that occur when fluids flow and how these phenomena may be described. Calculation of the details of the flow is usually secondary to understanding flow phenomena well enough to accomplish a process task; thus emphasis is on qualitative descriptions of characteristic phenomena for a variety of typically encountered configurations: flow in ducts, around obstacles, and in jets, wakes, and plumes. Besides the commonly encountered single‐phase Newtonian fluid, attention is given to non‐Newtonian fluids and two‐phase flows. The issue of flow instability is addressed. Those fluid flow phenomena that significantly affect heat and mass transfer and chemical reactions are presented. Practical calculational procedures are discussed for solving complex flow phenomena for both laminar and turbulent flow regimes. Techniques for flow modeling are also given. Some methods of flow measurement are also included.
Fluorinated Aromatic Compounds
Authors: Boudakian Max M.
Published: July 2004

This article covers the preparation, properties, reactions, and applications of three types of fluorinated aromatic compounds: ring‐fluorinated aromatics, side‐chain fluorinated aromatics and arylfluoroalkyl ethers, and fluorinated nitrogen heterocyclics.

The special properties conferred by fluorine justify the higher costs required to produce fluoroaromatics. Depending on which substituents are present, fluoroaromatic intermediates can be converted into fluorinated or fluorine‐free commercial end products. Fluorine‐containing aromatics have been incorporated into drugs (hypnotics, tranquilizers, antiinflammatory agents, analgesics, antibacterials) and into crop‐protection chemicals (herbicides, insecticides, fungicides). Liquid crystals, positron emission tomography, and imaging systems represent new areas where fluoroaromatics and fluoroheterocyclics have gained attention.

For fluorine‐free end products, the lability of fluorine in fluoronitrobenzenes and other activated molecules permit it to serve as a handle in hair dye manufacturing operations, high performance polymers (eg, PEEK), drugs (eg, diuretics), fiber‐reactive dyes, analytical applications, and biological diagnostic reagents.
Fluorethanols
Authors: Elliott Arthur J.
Published: July 2004

This article concerns ethanol fluorinated at carbon 2. 2‐Fluoroethanol behaves like a typical alcohol in its chemical reactions and is slightly more acidic than ethanol. It is usually prepared by reaction of potassium fluoride with 2‐chloroethanol or by the addition of hydrogen fluoride to ethylene oxide. It is extremely toxic due to its facile oxidation to fluoroacetic acid. 2,2‐Difluoroethanol is also more acidic than ethanol. It is prepared by the hydrolysis of 2‐bromo‐1,1‐difluoroethane. 2,2,2‐Trifluoroethanol is the most acidic fluoroethanol and has the unusual property of dissolving most polyamides (nylons and polypeptides) at room temperature. It behaves like a typical alcohol and the trifluoromethyl group is inert to most reagents. It is prepared by the reduction of trifluoroacetic acid and its derivatives. Because of its excellent combination of physical and thermodynamic properties, it has been used (mixed with water) as a working fluid for recovery of energy from waste heat sources. It is the only fluorinated ethanol available in commercial quantities, and finds use as the starting material for two inhalation anesthetics.
Fluorinated Acetic Acids
Authors: Elliott Arthur J.
Published: July 2004

Fluoroacetic acid is a carboxylic acid with slightly higher than average acidity that undergoes reactions typical of acetic acid. It is conveniently prepared by reaction of fluoride ion with chloro‐ or bromoacetic acid esters, followed by ester hydrolysis. It is extremely toxic and its sodium salt is one of the most effective all‐purpose rodenticides known. Difluoroacetic acid also undergoes reactions of a typical carboxylic acid and is a moderately strong acid due to the electron‐withdrawing nature of the fluorine atoms. It is much less toxic than fluoroacetic acid, and is best prepared by reaction of tetrafluoroethylene with ammonia, followed by alkaline hydrolysis of the intermediate triazine. Trifluoroacetic acid is a strong carboxylic acid but poses no unusual toxicity problems except for its acidic nature. It is a good solvent for proteins and polyesters. The trifluoromethyl group is essentially inert to most common reagents, and trifluoroacetic acid is usually prepared by oxidation of compounds containing the trifluoromethyl group. It is the only fluoroacetic acid produced in significant commercial quantities.
Fluorescent Whitening Agents
Authors: McElhone Harold J.
Published: July 2004

The absorption of short‐wavelength light (violet‐to‐blue) results in a yellow cast to fabrics. Fluorescent whitening agents (FWAs) absorb the invisible uv portion of the daylight spectrum and convert this energy into the longer‐wavelength visible portion of the spectrum, ie, into blue to blue‐violet light. This can be used to replace the light lost through absorption, thereby attaining a neutral, complete white.

Fluorescent whitening agents in use in the 1990s are aromatic or heterocyclic compounds; many contain condensed ring systems. Almost all of these compounds are derivatives of stilbene or 4,4′‐diaminostilbene; biphenyl; five‐membered heterocycles, eg, triazoles, oxazoles, etc; or six‐membered heterocycles, eg, coumarins, naphthalimide, etc.

Fluorescent whitening agents find use in the textile, paper, and synthetic fiber and plastics industries.
Fluorinated Aliphatic Compounds
Authors: Smart Bruce E. , Fernandez Richard E.
Published: July 2004

The physical, chemical, and toxicological properties of perfluorocarbons (PFCs), chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), hydrofluorocarbons (HFCs), and bromo‐ or iodofluorinated derivatives are reviewed. The principal methods for their manufacture, including cobalt trifluoride or electrochemical fluorinations, and liquid‐ or vapor‐phase additions and halogen exchanges with hydrofluoric acid are discussed. The diverse commercial uses of fluorinated aliphatics are described with particular emphasis on the primary high volume markets for refrigerants, foam‐blowing agents, propellants, and cleaning agents. The ozone‐depleting potentials of chlorodifluoromethane (HCFC‐22) and the CFCs traditionally used in these markets including fluorotrichloromethane (CFC‐11), dichlorodifluoromethane (CFC‐12), 1,1,2‐trichlorotrifluoromethane (CFC‐113), 1,2‐dichlorotetrafluoroethane (CFC‐114), and chloropentafluoroethane (CFC‐115), and those of the principal brominated materials used as fire extinguishants, bromotrifluoromethane (H‐13B1) and bromochlorodifluoromethane (H‐12B1), are discussed. The impact of the Montreal Protocol on internationally regulating the manufacture of ozone‐depleting materials, especially CFCs, and the industry's progress in developing suitable replacements are reviewed. The properties of the CFCs are compared to those of their leading replacement candidates including 1,1,1,2‐tetrafluoroethane (HFC‐134a), pentafluoroethane (HFC‐125), 1,1‐dichloro‐2,2,2‐trifluoroethane (HCFC‐123), 1‐chloro‐1,2,2,2‐tetrafluoroethane (HCFC‐124), 1,1‐dichloro‐1‐fluoroethane (HCFC‐141b), 1‐chloro‐1,1‐difluoroethane (HCFC‐142b), 1,1‐dichloro‐2,2,3,3,3‐penta‐ fluoropropane (HCFC‐225ca), and 1,3‐dichloro‐1,1,2,2,3‐pentafluoropropane (HCFC‐225cb).
Fluorescent Pigments (Daylight)
Authors: Streitel Steven G.
Published: July 2004

Daylight‐fluorescent pigments are luminescent materials that require no artificially generated energy to reflect colored light and to give off fluorescent light. Fluorescent pigments are composed of dyed organic polymers that are formulated to be solvents for the fluorescence dyestuff. In contrast to ordinary colors, light emitted from a fluorescent color adds to the light returned by simple reflection to give the glow characteristic of daylight‐fluorescent materials.

History of fluorescent dyestuffs, theory of fluorescence, methods of manufacturing, economic aspects, uses of fluorescent colors, and commercial properties of fluorescent pigments and colorants, and health and safety factors are discussed.
Foams
Authors: Durian Douglas J. , Weitz David A.
Published: July 2004

Foam is a nonequilibrium dispersion of gas bubbles in a relatively smaller volume of liquid containing surface‐active molecules. Foams that are relatively stable can be thought of as a form of condensed matter both solid‐like in being able to resist shear elastically, and liquid‐like in being able to flow and deform into arbitrary shapes. In this article, the extent to which the macroscopic stability and rheology of liquid‐based foams can be understood in terms of the underlying structure and dynamics of the constituent gas bubbles and liquid films, and their ultimate origin in terms of the physical chemistry of surface‐active molecules preferentially adsorbed at the gas‐ liquid interfaces are reviewed. Existing measurement techniques and survey applications in which custom foams play an important role are also discussed.
Food Packaging
Authors: Brody Aaron L.
Published: July 2004

The primary purpose of food packaging is to protect food against environmental contaminants. Each food category, eg, ambient temperature, shelf stable, frozen, or chilled, has different requirements. Generally, product processing must be integrated with the package to optimize shelf‐life objective. Thus canned foods are both heated and hermetically sealed to exclude microbiological recontamination; dry foods are sealed against moisture access; frozen foods must be maintained at low temperatures and protected against moisture loss; and chilled foods are refrigerated while controlling the transmission of both moisture and air.

The most widely used packaging materials are paper and paperboard employed mostly in distribution channels. Second are metals; aluminum for cans to contain vacuum packaged foods dominates in this category. Glass has been declining as a package material because of weight, relative fragility, and high energy consumption. Plastic materials constitute only about 10% of the mass of package materials, but contain proportionately larger amount of food because of low densities. A variety of plastic materials is used for packaging depending on the food requirements, eg, polyethylenes, polyesters, polypropylenes, polystyrenes, nylons, poly(vinyl chlorides), etc. Among the structures employed are extrusion and injection blow‐molded bottles, and cast or blown films. High gas barrier plastics are coated, coextruded, or laminated to structural plastics to enhance properties.
Food Toxicants, Naturally Occurring
Authors: Hoskins Fred H.
Published: July 2004

Toxicants, substances which threaten the normal function of the body when ingested, occur naturally in some foods. Proteinaceous enzyme inhibitors are among the most widely distributed food toxicants, whereas phytoalexins, vasoactive amines, psychoactive alkaloids, oligosaccharides, nutrient chelates, mycotoxins, various antinutrients, and potential mutagens and carcinogens may also be encountered. However, acute intoxication from food toxicants is rare owing to the dilution effect of a normal and varied diet.
Forensic Chemistry
Authors: Fisher Barry A. J.
Published: July 2004

Forensic chemistry, the application of chemistry to the law, is used to assist courts in the interpretation of the relevancy of scientific findings obtained from the examination of physical evidence, most of which is organic in nature. Chemical forensic testing, which may involve forensic toxicology, identification of solid drug samples, or trace analysis by means of modern instrumental analysis techniques, is described.

In forensic toxicology, samples from a biological source are screened to confirm the presence of alcohol or drugs. Immunoassays combined with chromatographic techniques are most often employed. Solid‐dose drug samples are first subjected to the older spot and microcrystalline tests. Common drugs of abuse are discussed.

Trace evidence, a generic term for microscopic physical evidence, may be examined by various microscopic techniques. Photography and high intensity light sources are also important analytic tools.

Forensic serology, the characterization of blood and other biological materials, is also presented. Species origin and blood and DNA typing are discussed.
Forensic Chemistry
Authors: Rowe Walter F.
Published: July 2004

Forensic chemistry, the application of chemistry to the law, is used to assist courts in the interpretation of the relevancy of scientific findings obtained from the examination of physical evidence, most of which is organic in nature. Chemical forensic testing, which may involve forensic toxicology, identification of solid drug samples, or trace analysis by means of modern instrumental analysis techniques, is described.

In forensic toxicology, samples from a biological source are screened to confirm the presence of alcohol or drugs. Immunoassays combined with chromatographic techniques are most often employed. Solid‐dose drug samples are first subjected to the older spot and microcrystalline tests. Common drugs of abuse are discussed.

Trace evidence, a generic term for microscopic physical evidence, may be examined by various microscopic techniques. Photography and high intensity light sources are also important analytic tools.

Forensic serology, the characterization of blood and other biological materials, is also presented. Species origin and blood and DNA typing are discussed.
Formamide
Authors: Höhn A.
Published: July 2004

Form‐ amide is a hygroscopic liquid, freely miscible with water and lower alcohols but virtually insoluble in all aliphatic and aromatic hydrocarbons. It decomposes thermally either to ammonia and carbon monoxide or to hydrocyanic acid and water. Owing to its bifunctionality, it is a highly reactive molecule, but it became industrially important only after the development of high pressure production technology. There are only three producers of formamide, which mainly is manufactured either by direct synthesis from carbon monoxide and ammonia or, more importantly, in a two‐stage process by reaction of methyl formate with ammonia. It is used as an intermediate by the chemical industry, eg, for producing hydrocyanic acid, heterocyclic compounds, pharmaceuticals, crop protection agents, and pesticides. It is also used as a solvent for resins and plasticizers. Formamide is neither explosive nor spontaneously flammable in air. It exhibits no particular acute toxicity. Precautions include avoidance of prolonged inhalation of vapors or contact of the liquid with skin or eyes.
Fracture Mechanics
Authors: Crouch Barry A.
Published: July 2004

The concepts of fracture mechanics, a methodology which characterizes the resistance of a material to crack propagation, are described, beginning with the stresses around the tip of a crack in an elastic material. An alternative approach based on the energy available to grow a crack is also discussed. The complications arising from plastic yielding at the crack tip in real materials are described, together with the testing restrictions required to ensure a valid experimental measurement of fracture toughness. Linear elastic fracture mechanics or elastic‐plastic fracture mechanics may be appropriate, depending on the extent of plastic yielding in the test material. The application of fracture mechanics to fatigue crack growth, impact loading, and dynamic crack propagation problems is briefly reviewed. Design considerations for crack stability and lifetime prediction in cyclic loading are also considered.
Initiators, Free‐Radical
Authors: Myers Terry N.
Published: July 2004

Most commercial free‐radical applications employ initiators such as peroxides and azo compounds. Lesser amounts of carbon–carbon initiators and photoinitiators and high‐energy ionizing radiation are also used commercially to generate free radicals. The chemical initiators are substances possessing labile oxygen–oxygen, carbon–nitrogen, or carbon–carbon covalent bonds that under certain thermal, chemical, or photochemical conditions undergo homolytic scission of the labile bond to produce free radicals. The free radicals produced are useful in many industrial chain reactions, eg, halogenations, additions to carbon–carbon double bonds, polymerizations of vinyl monomers, grafting reactions, curing of rubbers and unsaturated polymers, cross‐linking of polyolefins, modification of polyolefins, and reactive processing.

In this article free‐radical initiator decomposition pathways are reviewed. Initiator reactivity is related to chemical structure and to first‐order decomposition parameters such as temperature, frequency factor, and activation energy. Reactivity of derived free radicals is also related to structure and to the occurrence of secondary reactions such as β‐scission and induced decomposition. The energy and the chemical properties of the free radicals determine commercial utility; thus the interrelation of initiators, their kinetics, and the radicals produced provide guidelines for initiator selection.
Fruit Juices
Authors: Shaw Philip E.
Published: July 2004

In 1993, frozen concentrated fruit juice for manufacturing was the principal juice product of international commerce. Consumers have demanded more ready‐to‐serve juice products, especially chilled single‐strength juices. Commercial aseptic packaging of single‐strength juices and juice drinks worldwide permits packaging in soft plastic packages that can be stored at higher temperatures for convenience and economy for the consumer. Raw materials are selected for suitability for juice production, except for apple juice production which still uses much cull fruit. Variety and maturity are important factors affecting suitability for juice production. When a range of varieties is available, blends are used to achieve uniformity of flavor. Fruit grown in a warmer climate and having a high sugar (content may be mixed with fruit from a cooler region to achieve a desired sugar‐acid balance. This sugar–acid ratio is based on °Brix readings, ie, wt % sugar, obtained with a refractometer, and on total acidity obtained by titration. Juice factories frequently employ field persons to advise growers on the application of sprays to the growing crops so that residues on harvested fruit are within prescribed limits. Payment for raw materials is frequently based on specifications that are either official government grades or stated market standards. Official graders may be employed to test each load.

There are many steps in the production of fruit juices. citrus tough peel must be kept separate from the juice during extraction. Deciduous fruits are crushed whole and the juice is then separated from the pulp, peel, and seeds, usually in a pressing operation. Pineapple juice has been the most popular tropical fruit juice consumed in the U.S. for many years. It has long been a by‐product of the pineapple canning industry. The production and sale of other tropical fruit juices has more recently received significant attention. Many tropical fruit juices are too pulpy or have harsh or exotic flavors which make 100% juice products unacceptable to most U.S. consumers. They are more acceptable as nectars containing 25–50% juice or as blended fruit drinks where their strong flavors are diluted or modified. In most markets fruit juice must be 100% juice and contain no additives. Commonly, a juice drink contains 10% fruit juice, which usually is a blend of several fruits. Consumption in the fruit drink/nectar market varies widely from country to country. In all significant markets orange juice predominates. In the United States apple juice is second, followed by grape and then grapefruit juice.
Fuel Cells
Authors: Larminie James
Published: July 2004

Fuel cells are devices that convert the chemical energy of a fuel directly into electrical energy and heat. This article begins by describing the operating principles of fuel cells, their construction, and the main problems currently limiting their commercial success. The thermodynamics of fuel cell systems is discussed, and also the effect of parameters such as pressure and temperature on cell voltage. Their use in conjunction with gas turbines is also addressed, and it is shown that this is a particularly advantageious way of operating. An overview of the main sources of losses in fuel cells is given.

Several different types of fuel cell are explained. This article divides them into six categories: the proton exchange membrane fuel cell (PEMFC), the direct methanol fuel cell (PEMFC), the alkaline fuel cell (AFC), the phosphoric acid fuel cell (PAFC), the molten carbonate fuel cell (MCFC), and finally the solid oxide fuel cell (SOFC). In all cases except one it is the electrolyte that distinguishes the different types. The special features, advantages, disadvantages, operating temperature, electrode and electrolyte construction, typical applications and fuels used are described for each of these six types of fuel cell.
Biomass Energy
Authors: Paisley Mark A.
Published: July 2004

Energy from biomass is increasing throughout the world as concerns relative to energy supply and environmental impacts grow. Biomass is an underutilized, renewable resource that can potentially replace fossil fuels as the primary energy supply. Historically, biomass has merely been used for heating. Today's developing energy technologies are broadening the uses of biomass well beyond simple combustion for heating. The flexibility of biomass as an input to conversion processes provides the ability to generate a wide range of energy products. These products include ethanol, fuel gas, steam, electric power, bio‐diesel, and, through synthesis applications, a suite of chemical intermediates and products. Technologies being developed or adapted for use with biomass feedstocks include gasification, pyrolysis, anaerobic digestion, and advanced fermentation from lignocellulosics. This article provides an overview of each of these technologies and their potential uses as a part of the world's energy supply.
Fuels from Waste
Authors: Tillman David A.
Published: July 2004

FUELS FROM WASTE
.
A significant number and variety of organic wastes are combusted in energy recovery systems including municipal solid waste (MSW), various forms of refuse‐derived fuel produced from MSW, and municipal sewage sludge; bark and other wood wastes from sawmills and other forest industry operations; spent pulping liquor from chemical pulp mills such as kraft and sulfite mills; wastewater treatment solids or sludges from pulp and paper operations; agribusiness wastes, methane‐rich gases generated from municipal waste landfills; industrial trash and specific wastes such as demolition debris, broken pallets, unrecyclable paper wastes, and related materials; off‐gases from pulp mills and chemical manufacturers; incinerable hazardous wastes generated regularly as a function of production processes; and a broad range of other specific specialty wastes. The practice of incinerating these materials has become increasingly prevalent in order to accomplish disposal in a cost‐effective, environmentally sensitive manner. Combustion of such wastes reduces the volume of material which must be disposed of in a landfill, reduces the airborne emissions resulting from plant operations and landfill operations, and permits some economic benefit through energy recovery.

The technologies used to combust wastes depend on the form and location of components to be burned. Critical concerns associated with energy generation from wastes include fuel composition characteristics; combustion characteristics; formation and control of airborne emissions including both criteria pollutants and air toxics, eg, trace metals; and the characteristics of bottom and flyash generated from waste combustion.

Because fuels from combustible organic wastes have long been economic in specific industries such as pulp mills, sawmills, sugar mills or factories, and other biomass processing operations, and because municipal waste‐to‐energy is becoming increasingly cost effective, these systems are continuing to be installed. The typical industrial system is used either to generate process steam or to generate both electricity and steam in a cogeneration application.
Furan Derivatives
Authors: Kottke R. H.
Published: July 2004

Furan is a 5‐membered heterocyclic, oxygen‐containing, unsaturated ring compound. From a chemical perspective it is the basic ring structure found in a whole class of industrially significant products. The furan nucleus is also found in a large number of biologically active materials. Compounds containing the furan ring (as well as the tetrahydrofuran ring) are usually referred to as furans. From a manufacturing standpoint, however, furfural is the feedstock from which all of the commercial furan derivatives are derived, as it the easiest and least expensive to manufacture. Furan is produced from furfural commercially by decarbonylation; loss of carbon monoxide from furfural gives furan directly. Tetrahydrofuran is the saturated analogue containing no double bonds. This article is limited primarily to simple furans in which the nucleus occurs as a free monocycle, and, in general, does not include compounds in which the furan ring is fused to another ring. Tetrahydrofuran is produced commercially from furfural by decarbonylation followed by hydrogenation; it is also produced by several different methods from other raw materials.

Furfural and furfuryl alcohol are specialty solvents. They also are reactive solvents and contribute low viscosity to resin formulations. Thermosetting resins containing furfural and/or furfuryl alcohol “furan resins” demonstrate specialty properties including corrosion resistance, high carbon yield, stability at elevated temperature, low fire hazard, and excellent physical strength. These properties are of industrial importance in making foundry molds and cores, fiberglass composites, mortars, cements, plastic insulation foams, refractory mixes, high carbon composites, and aggregate binders, among others.
Fusion Energy
Authors: Ellis William R.
Published: July 2004

As far as is known, nuclear fusion is the primary source of energy in the universe. It occurs when the nuclei of lighter elements, such as hydrogen, are fused together at extremely high temperatures and pressure to form heavier elements, such as helium. Whereas practical methods for harnessing fusion reactions and realizing the potential of this energy source have been sought since the 1950s, achieving the benefits of power from fusion has proved to be a difficult, long‐term challenge.

Fusion is widely held to be the ultimate resource for the world's long‐term energy needs. The fuel reserves for fusion are virtually limitless and available to all countries. Fusion fuels can be extracted from water. Fusion promises to be an energy source which is potentially safe and environmentally benign. Radiological and proliferation hazards are much smaller than for fission power plants. The atmospheric impact is negligible compared to fossil fuels, and adverse impacts on the Earth's ecological and geophysical processes are smaller than for large‐scale renewable energy sources. The economics and costs of fusion power plants are still being studied, but appear comparable to those for other medium‐ and long‐term energy sources. The promise of affordable essentially unlimited supplies of clean, safe energy, free of political boundaries, has motivated a world‐wide research effort to develop this energy resource.

The reactions of deuterium, tritium, and helium‐3,3He, having nuclear charges of 1, 1, and 2, respectively, are the easiest to initiate. These have the highest fusion reaction probabilities and the lowest reactant energies. Two diverse technical approaches to fusion power, magnetic confinement fusion, also known as magnetic fusion energy (MFE) and inertial confinement fusion, also known as inertial fusion energy (IFE) are being pursued worldwide. These form the basis of a large number of fusion research programs. Fusion energy research is also the primary avenue for the development of plasma physics as a scientific discipline.
Gallium and Gallium Compounds
Authors: Sabot Jean Louis , Lauvray Hubert
Published: July 2004

Gallium is a scarce but not a rare element. It is found most commonly in association with its immediate neighbors in the Periodic Table, ie, zinc, germanium, and aluminum. The concentration of gallium in the earth's crust, 10–20 g/t (10–20 ppm), is comparable to that of lead and arsenic. There is an abundance of aluminum ores and alumina plants, and less importantly to gallium production zinc ores and plants; these are the main sources of gallium. The physical properties of gallium, especially its thermal properties, are exceptional. It is easily supercooled. In accordance with its normal potential, gallium is chemically similar to zinc and is somewhat less reactive than aluminum. A minor amount of gallium is extracted as a by‐product from the zinc industry. The significant amount of primary gallium is recovered from the alumina industry. The main source is the sodium aluminate liquor from Bayer‐process plants that produce large quantities of alumina.

A large part of the wastes from the gallium arsenide industry is recovered for both economical and environmental reasons. Several processes are effective and are being used to recover both the gallium either as a metal, a salt, or a hydroxide for recycling, and the arsenic in some form for recycling or disposal. Gallium either comes from mining sources or is recycled from scrap.

Gallium has complete miscibility in the liquid state with aluminum, indium, tin, and zinc. No compounds are formed.

Numerous intermetallic gallium–transition element compounds have been reported. The toxicity of metallic gallium or gallium salts is very low. Gallium is used in the production of electronics and magnets, in medicine, as a petroleum industry catalyst, and in the solar reactions experiment.
Coal Conversion Processes, Gasification
Authors: Shadle Lawrence J. , Berry David A. , Syamlal Madhava
Published: July 2004

Coal gasification is presented in terms of the chemistry of coal conversion and the product gas characteristics, the historical development of coal gasifiers, variations in the types and performance of coal gasifiers, the configuration of gasification systems, and the status and economics of coal gasification. In many ways, coal gasification processes have been tailored to adapt to the different types of coal feedstocks available. Gasification technology is presented from a historical perspective considering early uses of coal, the first practical demonstration and utilization of coal gasification, and the evolution of the various processes used for coal gasification. The development of the gasification industry is traced from its inception to its current status in the world economy. Each type of gasifier is considered focusing on the process innovations required to meet the changing market needs. Complete gasification systems are described including typical system configurations, required system attributes, and aspects of the industry's environmental and performance demands. The current status, economics of gasification technology, and future of gasification are also discussed.