bluuebunny/crossref_metadata_2025_split huggingface dataset:
Thermoplastic Elastomers
Authors: Holden Geoffrey 
Published: July 2004

AbstractThermoplastic elastomers have many of the physical properties of vulcanized rubbers but can be processed as thermoplastics. This unique behavior has opened a new field of polymer science and technology. Since their commercial introduction in the 1960s, thermoplastic elastomers have become a significant part of the polymer industry. They are used in applications as diverse as adhesives, footwear, medical devices, automobile parts, and asphalt modification. Many of them are block copolymers with alternating hard and soft segments. The thermoplastic elastomers with polystyrene hard segments are the larget group and probably the most versatile; they can be produced over a wide range of hardness values and applied either in the molten state or from solution. Other examples are block copolymers with elastomers, either vulcanized or unvulcanized, in which the two components are intimately mixed together, but in most cases still remain as separate phases. Thermoplastic elastomers of this type are generally used as replacements for vulcanized rubbers. This article reviews the synthesis, morphology, structure–property relationships, and commercial applications of thermoplastic elastomers of all types.
Thermodynamics
Authors: Van Ness Hendrick C. , Abbott Michael M. 
Published: July 2004

Abstract
The first and second laws of thermodynamics are stated and applied to heat engines and refrigerators. Because chemical technology is concerned primarily with the processing of fluids, the dependence of volume on temperature and pressure and the phase behavior of gases and liquids are reviewed. The enthalpy, Helmholtz energy, and Gibbs energy are introduced, and the fundamental property relations that express these properties and the internal energy as functions of their special variables are developed. The energy balance for steady‐flow processes is presented, as are equations applying to the vapor–liquid phase transition. The property relations for ideal‐gas mixtures are developed, leading to the introduction of the fugacity, the fugacity coefficient, and residual properties, and their applications. Similar development of property relations for ideal solutions leads to the definition of excess properties. The criteria for phase equilibria and their application to vapor–liquid and other kinds of phase equilibria are considered. Finally, chemical‐reaction stoichiometry and the standard property changes of reaction are applied to chemical‐reaction equilibria.
Composite Materials, Thermoplastic Polymer‐Matrix
Authors: Wolf Clarence J. 
Published: July 2004

AbstractThe methods used to synthesize thermoplastic resins for use as the organic matrix for resin‐based thermoplastic composites are described. The synergism between the processing method chosen to prepare the composite and the synthesis route used to prepare the resin is emphasized. The synthesis and basic chemistry of commodity‐type resins, such as polyamides, polyolefins, polycarbonates, polyacrylates, and acetals, used in composites are discussed. In addition, the chemistry of advanced resin systems, such as polyether ketones, polysulfones, polysulfides, and polyimides, used in high performance composite systems also are presented. Both true thermoplastic resins and pseudothermoplastic resins, that is, resins that undergo some reaction during procesing, are discussed. Several new and potentially important methods for preparing thermoplastic resins for use in composites are highlighted.
Thiamine (B1)
Authors: Burdick David 
Published: July 2004

AbstractThiamine, usually meaning the hydrochloride, is a water‐soluble salt which as its pyrophosphate ester, plays essential roles in nearly all life forms as a cofactor for metabolic dehydrogenase and transketolase enzymes. Its biosynthesis in microorganisms and plants is tightly limited to very low levels by feedback and repression mechanisms. Animals are dependent on a regular supply in their diets to prevent deficiencies which can progress from mild subjective symptoms of malaise to serious degenerative disorders and death.Knowledge of the biosynthesis of thiamine is limited and manufacture from biosources is not practical. All world production of thiamine is by chemical synthesis. All three of the major manufacturing groups use variants of one synthesis wherein the thiazole group is built up on the pyrimidine ring. The common intermediate, known asGrewe diamine, is synthesized from malononitrile or acrylonitrile, formate synthons, and acetonitrile. The thiazole ring is derived from carbon disulfide, butyrolactone, and acetate esters by the common intermediate thiolthiamine, which is oxidized to thiamine sulfate and then converted to other salts. Thiamine is sold as the hydrochloride and mononitrate salts which are widely used in foods, feeds, and multivitamin supplements. Thiamine is safe and stable when dry or in acidic solution, but degrades with base, irradiation, and nucleophilic attack.Essentials of the history, occurrence, biosynthesis, biochemical and physiological functions, chemical transformations, manufacturing chemistry, analytical methods, safety and handling, product forms, derivatives, analogues, and uses of thiamine are discussed.
Magnetic Materials Thin Films and Particles
Authors: Wernick Jack 
Published: July 2004

AbstractHigh density recording materials for audio and video systems are comprised of magnetic materials in the form of thin films and particles. The magnetic properties of these systems are discussed. Materials systems used for tapes and disks include those based on iron oxide, chromium dioxide, ferrites, and iron‐ and cobalt‐based alloys. Metallic, ie, alloy‐based media are usually in the form of thin films, typically sputtered films having protective overcoats. Magnetic thin‐film deposition techniques are presented.The development of magnetooptical thin‐film material systems is of interest because of the need for greater capacity for the storage of digital information. Ferrimagnetic ternary amorphous alloys containing rare‐earth elements, as well as cobalt–platinum multilayers, are employed. Future developments are expected to focus on antiferromagnetically coupled superlattices exhibiting giant magnetoresistance. These magnetic superlattices are described.
Thiophene and Thiophene Derivatives
Authors: Fuller Lance S. 
Published: July 2004

AbstractIndustrial demand for thiophene and its derivatives has escalated since 1980. Applications in the electronic field will take it into the twenty‐first century, whereas pharmaceutical, agrochemical, and dyestuff requirements continue to account for existing demands. Synthesis of the parent ring system, along with simple alkyl derivatives, has changed little over the years. An outline of the vapor‐phase route, the best practical environmental option to produce these materials, is given. Ring synthesis of specific derivatives has been developed into commercial‐scale operations from chemistry identified in the late 1950s and early 1960s, following market interest in such products as dyestuff, agrochemical, and pharmaceutical intermediates. Reactions of the thiophene have been noted, along with useful spectroscopic and physical chemistry data as well as additional toxicity and ecotoxicity data for thiophene derivatives. Biotic degradation of thiophene is minimal, and halothiophenes, in particular, are environmentally hazardous in aqueous systems.
Thioglycolic Acid
Authors: Labat Y. 
Published: July 2004

AbstractThioglycolic acid and its derivatives as well as various other mercaptocarboxylic acids have become widespread. Both the mercapto and carboxylic functions in thioglycolic acid are chemically active, as is the methylene group in esters under alkaline conditions. The most important reactions involve the thio disulfide interchange reactions with cystine units in hair protein, keratin, which property is applied in cosmetology for hair waving, and the formation of esters to give tin stabilizers for poly(vinyl chloride). For esters, the ability to build N and S heterocycles promises prospective development in fine chemistry. Other mercaptocarboxylic acids have experienced interesting developments, mainly as polymer modifiers and polymer stabilizers.Thioglycolic acid is manufactured from the inexpensive starting materials chloroacetic acid and alkali sulfhydrates. Thioglycolic acid is degraded by self‐esterification but is stable at low temperatures. All processes which produce thioglycolic acid are characterized by salt formation.
Thiols
Authors: Roberts John S. 
Published: July 2004

AbstractThe chemistry of thiols is a diverse area. Many thiols are of economic importance, with applications such as rubber intermediates, cosmetics additives, herbicides, gas odorants, and lube additive intermediates. Thiols are characterized by their strong odor. The preparations and reactions of thiols, as well as their use as intermediates in the production of commercial products, are discussed.
Thorium and Thorium Compounds
Authors: Clark David L. , Keogh D. Ww , Neu Mary P. , Runde Wolfgang 
Published: July 2004

AbstractThorium, a naturally occurring radioisotope, and thorium compounds, primarily where thorium is present in the+4oxidation state, are discussed. The main interest in thorium is as a nuclear fuel, but thorium and its compounds have many specialty uses, for instance, as gas, lantern mantels, and catalysts. Thorium has a rich coordination and organometallic chemistry. A drawback to using thorium in many processes is the chemical reactivity of the metal as well as the inherent radioactivity of all thorium isotopes. Health and safety factors essential for working with thorium are discussed.
Titanium and Titanium Alloys
Authors: Froes F. H. (Sam) 
Published: July 2004

Abstract
Titanium, the ninth most abundant element, is used principally as an oxide in paint filler for its high refractory index and as a metal in aerospace and industrial applications for its high strength‐to‐density ratio and excellent corrosion resistance. This article covers the locations and reserves of principal ore bodies and their conversion by sulfate or chloride refining processes to high purity oxides for the pigment industry, and the conversion of the intermediate chloride by magnesium or sodium reduction to metallic sponge for the metal industry.
The principal metal melting processes to produce ingots from sponge are reviewed, along with the metalworking processes for converting ingots to mill products. The influence of alloying elements on properties and microstructure is discussed, along with the mechanical properties and characteristics of the principal alloys used in aerospace and industrial applications. Methods and procedures related to the fabrication of metal components into useful application components are covered. The primary uses of both the oxide and the metal are summarized, along with the economics associated with the production of the metal and oxide.
Toluene
Authors: Ozokwelu E. Dickson 
Published: July 2004

Abstract
Changes in the environment necessitate that information on commodity chemicals like toluene be updated periodically. Because of the global technological and economic changes that have occurred since 1983, considerable material on improved and emerging technologies for the manufacture of toluene and also on the economic aspects and uses of toluene are included.
Physical and chemical properties are presented. Manufacture and processing aspects treated include production of toluene along with benzene and xylenes from reformate and highlight the improvements on toluene–benzene recovery by extraction and extractive distillation. Lastly, emerging technologies for the manufacture of BTX from light hydrocarbons are reviewed. Toluene supply and demand are discussed. The declining effect of the introduction of Reformulated Gasoline in Fall 1994 on the use of toluene for gasoline blending and the increase in demand of toluene for use in disproportionation plants to produce xylenes are analyzed. Specifications, standards, and quality control are outlined. The analytical and test methods and storage procedures are listed, and health and safety factors (toxicology) are discussed. Uses and derivatives are presented.
Toxicology
Authors: Ballantyne Bryan , Fong William George 
Published: July 2004

AbstractToxicology is the study of interactions between chemicals and biological systems to determine quantitatively the potential for to produce injury resulting in adverse health effects. The relationship of exposure dose and the nature and magnitude of any effect, ie, dose‐response relationship information, is valuable in determining causal relation and relevance of exposure conditions, so as to allow estimates of hazard. Toxicological investigations attempt to define the nature of the harmful effect; severity of effect as a function of exposure dose; mechanism causing the effects; detection, recognition, and quantitation of toxic effects; and reversibility of toxic injury.Toxic effects may be classified as local or systemic; and as latent, persistent, cumulative, or transient. They include inflammation, necrosis, immunosuppression, neoplasia, mutagenesis, enzyme inhibition, teratogenesis, and others. Factors influencing toxicity include number, magnitude, and routes of exposures; and time of dosing, as well as formulation and impurities of materials. Routes of exposure include swallowing, through the skin, inhalation, and through the eye, and may also be multiple. The discrepancy of amount of a material passing to the liver related to route of exposure may influence the degree of toxicity, as may the residence time of materials and their metabolites in an organism before excretion and their capacity for storage.Dose–response relationships are useful in determining causality, range of sensitivity in a population and hence of hazard, assessment of no‐ or minimum‐effects doses, and comparisons of materials and species.Toxicology testing procedures may be general or specific, and many guidelines must be followed. General studies monitor body weight, hematology, chemical pathology, and organ weight, among others, and types of studies include acute toxicity studies, short‐term repeated studies, and chronic and subchronic toxicity studies. Examples of specific studies include primary irritancy and immune‐mediated hypersensitivity studies, and neurological and behavior toxicology. Review of studies and the relevance of toxicology in hazard evaluation are briefly examined.
Chlorocarbons and Chlorohydrocarbons, Toxic Aromatics
Authors: Safe Stephen H. 
Published: July 2004

AbstractHalogenated hydrocarbons such as the polychlorinated biphenyls (PCBs), hydroxy‐PCBs, polybrominated diphenyl ethers (PBDEs), polychlorinated naphthalenes (PCNs), and chlorinated insecticides (lindane) have been widely used industrial compounds. These chemicals are lipophilic and their release into the environment results in bioaccumulation in adipose tissue and persistence due to their chemical stability and resistance to metabolic breakdown. Thus, the more widely used PCBs and lindane have been identified in almost every component of the global ecosystem including fish, wildlife, and humans. Risk and hazard assessment of the highly complex halogenated hydrocarbon mixtures is difficult; however, at least one subgroup of chemicals within these mixtures can be evaluated. Several PCB congeners exhibit aryl hydrocarbon receptor (AhR) agonist activities and their potencies relative to 2,3,7,8‐tetrachlorodibenzo‐p‐dioxin (TCDD) have been determined and used to calculate TCDD or toxic equivalents (TEQs) for various mixtures. However, risk assessment of most other halogenated hydrocarbons is not well defined and requires further research to determine their activities and relative potencies.
Trace and Residue Analysis
Authors: Ahuja Satinder 
Published: July 2004

AbstractIt is generally recognized that trace analysis implies those analyses that are carried out around 0.0001% or ppm level. Ultratrace analysis, ie, beyond what is ordinarily called trace analysis, can be then defined as analysis performed below ppm or µg/g level. Residue analysis relates to the analysis of residual materials left from an operation, eg, solvents left in pharmaceutical products or pesticides left in food. Analyses performed at or below ppm level are described. Sampling, sample preparation, sample cleanup, and method validation are discussed. In addition, a number of methodologies are covered, such as atomic absorption/emission spectrometry, neutron activation analysis, tlc, gc, hplc, hyphenated methods such as gc/ms and lc/ms, capillary electrophoresis, supercritical fluid chromatography, and immunoassays that allow analyses of both organic and inorganic samples. Applications include areas such as environment, explosives, food, pharmaceuticals, biotechnology, and a number of miscellaneous fields.
Transportation
Authors: Hoffman Stanley , Moreno Jeffrey O. , Booth Karyn A. , Cobb Antoine P. , Fortin Richard D. 
Published: July 2004

AbstractA wide range of issues and matters relevant to the transport of chemicals is addressed. In particular, the various modes of transport, including railroad, motor carrier, water carrier, pipelines, and air transport, and the role played by each in the transport of chemicals is discussed. In addition, the significance of regularly used shipping terms and documents are explained. The different laws applicable to interstate and intrastate transportation, and how to identify under which jurisdiction a particular shipment will be regulated, also are addressed. Changes in the economic regulation of the various modes of transport are explained and the significance of those changes to chemicals shippers is explored. Economic regulation includes important distinctions between contract, common, and private carriage, and the allocation of responsibility between shippers and carriers for freight loss and damage. Finally, safety and hazardous materials transport regulations, a critical concern for chemical shippers and carriers alike, are discussed.
Triphenylmethane and Related Dyes
Authors: Thetford Dean 
Published: July 2004

AbstractA brief introduction describing the structure and dyeing properties, eg, lightfastness and color, of the triphenylmethane dyes is given. The dyes are also classified in terms of their application class, giving their historical and present‐day usage in textiles and paper. Further details on the relationship of the structure and the various substituents on the reactivity, spectral characteristics, and fastness properties are discussed.The significant industrial processes for the manufacture of triphenylmethane dyes are outlined through examples of the synthesis of the more important dyes like malachite green, methyl violet, and crystal violet. New reagents and kinds of chemical technology are described where these have been used to improve the older processes and alleviate environmental problems. The toxicology associated with the triphenylmethane dyes is also mentioned in relation to their use as food colorants or dyes, and the environmental concerns of effluent treatment is briefly mentioned.Production statistics for triphenylmethane dyes in the United States are given for the period between 1975 and 1995, with suitable references also provided giving world figures. The many different areas in which these dyes are employed are described, along with more recent high technology uses.
Tungsten Compounds
Authors: Penrice Thomas W. 
Published: July 2004

AbstractTungsten combines with many other elements to form simple stable compounds. It readily polymerizes but the chemistry of aqueous solutions is very complex. This is exemplified by the large number of polytungstates. The chemical uses of tungsten have increased substantially in more recent years.The hexacarbonyl has potential as a lubricant additive and as a dye and pigment. The halides are useful as starting materials in the chemical vapor deposition of tungsten. The oxides are important intermediate products in the stepwise reduction in hydrogen to the metal. Tungsten bronzes constitute a series of well‐defined nonstoichiometric compounds. The sodium tungsten bronzes are interesting not only for their intense color range but exhibit both positive and negative coefficient of resistance as the sodium:tungsten ratio changes. Sodium tungsten bronzes help the catalytic oxidation of carbon monoxide and reformer gas in fuel cells.The tungstates are an important class of materials. The metatungstates are important starting materials for production of tungsten catalysts because of the high solubility in water. Ammonium paratungstate is the intermediate material of choice between chemical recovery from ores and the reduction to tungsten metal. The interstitial compounds, particularly with carbon, represent the largest application for tungsten in cemented carbides. Tungsten compounds, especially the oxides, sulphides, and heteropoly complexes, form stable catalysts for a variety of chemical processes in the petroleum industry and in chemical synthesis. Other uses include fireproofing of textiles, as additives in lubricants and antifreeze solutions, in inks and dyes, as phosphors in fluorescent lights, and for improvement of conductivity of tin oxide coatings on aircraft windows. Because soluble tungsten compounds show varying degrees of toxicity, exposures in the workplace are regulated.
Urethane Polymers
Authors: Ulrich Henri 
Published: July 2004

AbstractThe properties of thermoplastic and thermoset polyurethanes are discussed. The subjects include flexible and rigid polyurethane foams, poly(urethane isocyanurate) foams, thermoplastic polyurethane elastomers, thermoset cast and RIM elastomers, engineering thermoplastics, liquid crystalline polyurethanes, and polyurethane containing interpenetrating polymer networks. Principal raw materials, such as isocyanates, polyether polyols, and polyester polyols, as well as catalysts, fire retardants, and surfactants, are described. The manufacture of flexible foam, rigid foam, coatings, adhesives, sealants, and elastomers are included, as is the use of polyurethane ionomers in aqueous dispersions and blocked isocyanates in one‐component and powder coatings applications. The global trend in polyurethanes is a shift from toluene diisocyanate‐based formulations to polymeric isocyanate and 4,4′‐methylenebis(phenyl isocyanate) whenever possible, and substitution of chlorinated fluorocarbon blowing agents by hydrochlorofluorocarbons, hydrofluorocarbons, or hydrocarbons. Recycling of polyurethanes, health and safety factors, including toxicity and safe handling of isocyanates and tertiary amine catalysts, as well as principal uses of polyurethanes and market information, are all discussed.
Vaccine Technology
Authors: Hsieh Chia‐Lung , Ritchey Mary B. 
Published: July 2004

AbstractA vaccine is a preparation used to prevent a specific infectious disease by inducing immunity in the host against the pathogenic microorganism. The practice is also called immunization. Beginning in the 1950s, with the discovery of antibiotics, interest in vaccine research faded; however, the development of biotechnology and modern immunology has created new opportunities for producing new antigens and vaccine research has become a significant focus once again. Vaccines have been developed against poliomyelitis, diphtheria, tetanus, pertussis, measles, mumps, rubella,Haemophilus influenzaserotype b, hepatitis B, and varicella are all in commercial use. Vaccines being developed include those against meningitis, rotavirus, respiratory syncytial virus, parainfluenze, otitis media, herpes simplex, influenza, malaria, gonorrhea, and the human immunodeficiency virus. All are discussed, as well as future technology, the effects of genetic engineering, adjuvants, and economic aspects.