bluuebunny/crossref_metadata_2025_split huggingface dataset:
Polyesters, Thermoplastic
Authors: East Anthony J. , Golder Michael , Makhija Subhash 
Published: July 2004

AbstractThis article covers semicrystalline thermoplastic polyesters and their applications as molding resins. The principal polymers described are PET, PBT, PEN, PCT, thermoplastic elastomers of the PBT–PTMEG‐T type, and liquid crystalline polymers. The raw materials for various polyesters and their production are described and general routes to polyester polymer synthesis outlined. Individual polyesters are described in more detail with particular reference to special features of their polymer chemistry. PET stretch blow‐molded bottles and containers are a very large market and the production of PET bottle resin by continuous polymerization and solid‐state polymerization is described together with an outline of the stretch blow‐molding process. Physical properties, polymer characterization and mechanical properties together with details of polymer injection molding are described.Particular reference is given to the growing demands for PCT of new electronic and electrical fabrication techniques such as surface mounting technology and its requirements for high temperature polymer properties. PBT polymer is described in detail. Flame‐retardant additives are described and how they affect polymer performance. Safety and health factors for the polymers in use are discussed.Liquid crystal polymers are relatively new high performance thermoplastics. The nature of the mesophase state and how LCP's differ from conventional materials is described. LCP polymer synthesis is outlined and physical and mechanical properties of several commercial LCP polymers given.
Poly (Vinyl Fluoride)
Authors: Ebnesajjad Sina 
Published: July 2004

AbstractHomopolymers and copolymers of vinyl fluoride are based on free‐radical polymerization of vinyl fluoride and comonomers, usually under high pressure. Du Pont first commercialized a poly(vinyl fluoride)‐based film in 1961 under the trade name Tedlar. Poly(vinyl fluoride) homopolymers and copolymers have excellent resistance to sunlight degradation, chemical attack, water absorption, and solvent; they have a high solar energy transmittance rate. These properties have resulted in the utilization of poly(vinyl fluoride) (PVF) film and coating in outdoor and indoor functional and decorative applications. These films are used where exceptional high temperature stability, outdoor longevity, stain resistance, adherence, and release properties are required.
Polymers Containing Sulfur, Poly(Phenylene Sulfide)
Authors: Geibel Jon , Leland John 
Published: July 2004

AbstractPoly(p‐phenylene sulfide) (PPS) is an important industrial thermoplastic material. This article reviews the history, syntheses (both laboratory and commercial), and properties of PPS. Characteristics such as thermal transition, thermal stability, rheology, solution viscometry, size‐exclusion chromatography, UL temperature indexes, mechanical properties, chemical resistance, and electrical properties of neat PPS resin and reinforced PPS compounds, are all discussed. Significant areas where PPS resins are used are presented.
Fibers, Poly(Vinyl Alcohol)
Authors: Hikasa Jun‐ichi 
Published: July 2004

Abstract
Commercial production of poly(vinyl alcohol) fiber started in 1950, 20 years after the inventors of the resin had tried to form it into fiber. PVA fiber is manufactured by wet spinning methods and a dry spinning method. There are variations of the former method which have been developed to improve the quality of the fiber.
Characteristics of PVA fiber are high strength, low elongation, and high modulus. This fiber is also very hygroscopic, has good dimensional stability under dry heat, and has good chemical resistance to various agents. In particular, PVA fiber exhibits high resistance to alkali.
This fiber has been used for clothing and interior applications, but now it is used for various industrial applications because of its superior mechanical properties of high strength and modulus, resistance to chemicals, high durability against uv rays, etc. The main fields of application are in the rubber industry, agriculture, fishing, nonwovens, paper, plastic reinforcement, cement reinforcement, and others.
Polymethine Dyes
Authors: Kachkovski Alexy D. 
Published: July 2004

AbstractPolymethine dyes (PMDs) encompass a large class of linear, conjugated, colored systems in the general form of\documentclass{article}\usepackage{amssymb}\pagestyle{empty}\begin{document}${{(}{\rm{G^{\pm }_{1}}}{\relbar \kern-5pt{\relbar}\kern-7pt{\relbar}}{\hskip-7pt}{(}{\hskip0.167em}{\rm{CH}}{\raise1pt\hbox{$\Relbar \kern-4pt{\Relbar}$}}{\rm{CH}}{\relbar \kern-5pt{\relbar}\kern-7pt{\relbar}}{\hskip-9pt}{)}_{n}{\rm{CH}}{\raise1pt\hbox{$\Relbar \kern-4pt{\Relbar}$}}{\rm{G_{2}}}{)}{\rm{X^{\mp }}}}$\end{document}, where G1and G2are end groups. In the ground and first excited states, the carbon–carbon bonds within the polymethine chain are practically equalized and alternating positive and negative charges appear at the carbon atoms. The main topological factors affecting PMD color are chain length, nature of end groups, electron shell occupation, asymmetry, chain branching, and chromophore interaction.Polymethines are highly reactive compounds. Their photochemistry, protonation, and reactions with electrophiles, nucleophiles, reactants, and radicals are surveyed. The most important reason for the extremely wide technical uses of PMD is their low electron‐transition energies. Attention is paid to the application of polymethines as spectral sensitizers, laser dyes, and polymerization initiators. Synthetic methods for obtaining PMDs with various chain lengths, end groups, and chromophore modification are summarized, along with molecular designs and economic aspects.
Polymer Blends
Authors: Keskkula H. , Paul D. R. , Barlow J. W. 
Published: July 2004

AbstractThe physical approach of blending polymers to develop new or improved polymeric products has been an extremely active area of academic and industrial research for nearly three decades, owing to the much higher costs associated with the alternative of chemical synthesis of new polymers. This activity has been paced by the rapid commercialization of products based on blend technology, including polyamide‐, polyester‐, styrenic‐, vinyl‐, acrylic‐, olefinic‐, and epoxy‐ based materials. The basic principles needed to practice this approach are reviewed, including molecular and thermodynamic factors affecting blend‐phase behavior (miscibility or compatibility), phase morphology, processing, interfacial behavior, and chemical reactions that can occur. General trends and examples of physical properties are given, with special emphasis on the important commercial developments, followed by speculations about future developments.
Polymers of Higher Olefins
Authors: Kissin Yury V. 
Published: July 2004

AbstractThe article describes polymeric materials derived from the higher α‐olefins with carbon atom numbers of four or higher as well as polymers of cycloolefins. Crystalline polymers of higher α‐olefins belong to two classes of stereoregular polymers, isotactic and syndiotactic. Isotactic polymers are produced with two types of catalysts, heterogeneous Ziegler‐Natta catalysts and bridged metallocene catalysts. Other metallocene catalysts produce either crystalline syndiotactic polymers or amorphous atactic polymers. Higher α‐olefins can also be polymerized with cationic initiators to amorphous oligomeric materials. Cycloolefins are polymerized by two different mechanisms: the ring‐opening metathesis reaction catalyzed by tungsten or molybdenum compounds, and polymerization reactions without ring opening catalyzed by metallocenes.Two isotactic polymers of higher α‐olefins, poly(1‐butene) and poly(4‐methyl‐1‐pentene), as well as oligomers of linear α‐olefins and polymers of certain cycloolefins (polydicyclopentadiene, polyoctenamers, and norbornene elastomers) are produced commercially. Crystalline poly(1‐butene) is used to manufacture pipe, tubing, and blown film. Crystalline poly(4‐methyl‐1‐pentene) is a highly transparent plastic used for the manufacture of medical and chemical laboratory equipment as well as a variety of injection‐molded articles. Liquid oligomers of higher linear α‐olefins produced with cationic initiators have found wide applications as base oils in the formulation of various industrial lubricants; among other applications, they are used in synthetic lubricating oils for cars, transformer oils, and transmission and crankcase fluids. Polymers of cyclooctene are mostly used as components in rubber and compositions based on PVC or polystyrene. Cured liquid‐molding resins based on polydicyclopentadiene are used for the manufacture of automotive parts for trucks, snowmobiles, wheel loaders, and recreational vehicles.
Polyimides
Authors: Takekoshi Tohru 
Published: July 2004

AbstractPolyimides are high performance polymers employed as key materials in advanced industrial applications, including aerospace, electrical, and electronic engineering. Polyimides are capable of functioning at high temperature and in oxidative environments, and have outstanding mechanical strength, excellent electrical properties, and wide ranging chemical resistance. One of the advantageous characteristics of polyimides over other high temperature polymers is their processibility through soluble intermediates. Polyimide polymerization is a thermodynamically driven condensation reaction and can be performed in a simple manner, includingin situpolymerization. It is also a versatile system in terms of synthesizing wide varieties of copolymer compositions for the required properties. In this article, various synthetic methods for polyimides, and properties and applications of principal commercial polyimides, are reviewed. Advances in the chemistry and applications of polyimides are also described.
Polyhydroxyalkanoates
Authors: Tan Irene K. P. 
Published: July 2004

AbstractPolyhydroxyalkanoates (PHA) occur naturally as water‐insoluble inclusion bodies within the cytoplasm of a variety of bacteria. They have garnered global interest because they have properties similar to petrochemical‐derived plastics, in addition to which they are also biodegradable and biocompatible, and are synthesized from renewable resources. The two main classes, short‐chain‐length PHA (PHASCL) and medium‐chain‐length PHA (PHAMCL), are synthesized in non‐pseudomonads and fluorescent pseudomonads, respectively, along different biosynthetic routes. The production of bacterial PHA by fermentation is well developed, the highest yield being obtained from recombinant strains. Nevertheless, the production cost of PHA is currently many times higher than petrochemical plastics which thus makes PHA economically unviable to be used for bulk commodities. There is, however, much potential for PHA to be used in biomedical applications. Areas of on‐going R&D include improving the fermentation and recovery processes as means to increase PHA yield and reduce processing costs while developing processes that reduce negative impacts on the environment.In vitrobiosynthesis using purified enzymes (eg, PHA synthase) and activated precursors (eg, 4‐hydroxybutyryl‐CoA), and the technology to effectively recycle the enzymes is another area of active study. The development of transgenic plants that produce PHA, like how starch and vegetable oils are produced, is widely believed to hold the key to viable large scale production of PHA at costs that allow the material to be used for common disposable products that are the major plastic pollutants.
Polymers Containing Sulfur, Polysulfides
Authors: Vietti David , Scherrer Micheal 
Published: July 2004

Abstract
Polysulfide elastomers were the first synthetic rubbers made in the United States. They are prepared from simple low cost starting materials and the thiol end group provides a variety of chemical approaches to curing. The most common method is through oxidative coupling. Polysulfides can also be cured with diisocyanates or epoxies. They are commonly used as a flexibilizer and reactive diluent in epoxy formulations. Their unusually good resistance to solvents and to the environment and good low temperature properties have made them particularly useful in sealant applications. They are the standard sealant for virtually all aircraft integral fuel tanks and bodies. Polysulfides are the worldwide market leader in insulating glass sealants and have been used since the 1950s as construction sealants. Polysulfide elastomers' broad spectrum of chemical and solvent resistance and other unique properties make them useful in a variety of specialty rubber applications.
Hormones, Posterior Pituitary Hormones
Authors: Spatola Arno F. 
Published: July 2004

AbstractOxytocin and vasopressin are cyclic peptide hormones primarily synthesized in the human hypothalamus and stored in the posterior pituitary. These nonapeptide amides, along with at least 14 other variants found in lower vertebrates and invertebrates, contain cysteine residues at positions 1 and 6, forming a disulfide bridged ring, along with a tripeptide C‐terminal extension. The hormones are stored in neurosecretory granules with their respective carrier proteins, the neurophysins, prior to release into the bloodstream.Oxytocin promotes milk ejection and uterine contraction; human arginine vasopressin promotes water retention and exerts a pressor effect. Both hormones or their analogues are used clinically and both are being intensively studied for additional physiological effects. These include nurturing behavior in women and penile erection in men for oxytocin, and memory consolidation for arginine vasopressin and analogues.Receptors, including some receptor subtypes, have been cloned for both hormones. Oxytocin and V1receptors function through the GP/1 phospholipase C complex, whereas V2receptors activate adenosine monophosphatase (AMP). Selective peptide and nonpeptide, ie, peptidomimetic, analogues are being developed that should offer improved therapeutic utility.
Potassium Compounds
Authors: Freilich Mark B. , Petersen Richard L. 
Published: July 2004

Abstract
Water‐soluble salts of potassium, collectively called potash, are important for the manufacture of numerous articles of commerce and for direct application as fertilizers. Other uses of potassium compounds range from use in specialty glass to that of food additives. Potassium chloride, the most commonly used potash and the raw material for the manufacture of most of the other potassium compounds, is principally obtained from the mining of sylvinite. The ore refinement process, which includes crushing, scrubbing, hydraulic desliming, froth flotation, centrifugation, and drying is described. Potassium hydroxide is produced industrially by electrolysis of the chloride. The hydroxide is used for the production of the commercially important potassium carbonate and potassium phosphates. Several processes are used to convert potassium chloride to other potassium compounds such as the sulfate. Potassium magnesium sulfate is also an important fertilizer. Other compounds of commercial importance include the potassium salts of acetate, bromide, bicarbonate, formate, iodide, permanganate, and acid tartrate. Potassium has an essential role for the biochemistry of both plants and animals. Potassium compounds commonly used in fertilizers are not considered to be hazardous; however, potassium may be paired with a poisonous, corrosive, or oxidizing anion and requires special handling.
Coating Processes, Powder Technology
Authors: Richart Douglas S. 
Published: July 2004

AbstractMethods for applying decorative and protective coatings utilizing finely divided powders followed by heat fusion of the powder particles to form a continuous film are gaining in popularity and commercial acceptance. Since there are no volatile organic compounds present, powder coating is an environmentally friendly, nonpolluting coating process, providing coatings with improved performance as well. Powder coatings can be found on many common items including lawn and garden equipment, outdoor metal furniture, display racks, architectural aluminum panels and trim, and many automotive compounds including the exterior clear coat.The chemistry and composition of powders used in coatings and their properties are described, as well as their method of manufacture, processes used to apply them, their applications and a review of health, safety and environmental considerations. Over 100 references are supplied to provide more detailed technical information.
Power Generation
Authors: Collins Steven 
Published: July 2004

Abstract
The basic processes and equipment used to generate power, whether mechanical or electrical, have advanced significantly in the twentieth century. Fossil fuel‐fired power plants remain the main sources of power generation, although nuclear fuels provide a large percentage of power worldwide. Power generation facilities harness the thermal energy released during the combustion of fossil fuels or the fission of nuclear ones and convert this thermal energy to electricity for transmission and distribution to users. Predominant fossil fuel plant types include conventional boiler‐based Rankine cycle facilities; engine‐based plants relying on combustion turbines (Brayton cycle) or reciprocating engines (Carnot cycle); and combined‐cycle plants relying on a combination of technologies. The various arrangements of the components, the thermodynamic factors, and the efficiencies of these systems are described. Fuel handling and storage, combustion and process control, water and waste treatment, as well as emissions monitoring and control for fossil fuel‐fired plant operations are discussed. Renewable energy technologies, particularly hydroelectric generation, have also been widely applied and demonstrated. Advanced technologies, such as electrochemical fuel cells, hold promise for the future. Many of the principles related to the operation of conventional fossil fuel‐fired plants are also employed in nuclear stations, waste‐fired plants, and renewable energy facilities.
Regulatory Agencies, Power Generation
Authors: Collins Steven 
Published: July 2004

Abstract
Entities involved in the generation of electric power in the United States are subject to regulation by different state and federal agencies. Numerous regulations and laws are in place to protect the environment and ensure fair business practices, stable energy supply, and consumer protection. This article both summarizes the history of electric utility business and environmental regulations in the United States, and discusses the various policies of and roles played by such keys agencies as the U.S. Federal Energy Regulatory Commission, Nuclear Regulatory Commission, and Occupational Safety and Health Administration.
Pressure Measurement
Authors: Ryans J. L. 
Published: July 2004

AbstractPressure measurement spans the range from 1,380 MPa (200,000 psig) and higher to\documentclass{article}\pagestyle{empty}\begin{document}${10^{-10}{\hskip0.167em}{\hskip0.167em}{\rm{Pa}}}$\end{document}, ie, extreme ultrahigh vacuum. Pressure, particularly where it is monitored as opposed to being controlled, is generally measured by mechanical elements. Mechanical pressure gauges are reliable and inexpensive. They dominate process applications in older plants, and the sensing elements for many of the sophisticated electronic transmitters contain simple mechanical elements. The shift away from mechanical sensors to electronic sensors in the chemical process industries is a result of the superior accuracy and reliability of electronic instrumentation. Piezoelectric pressure elements, reluctive pressure transducers, strain gauges, piezoresistive sensors, and capacitive pressure transducers, the principal types of electronic sensors, are described herein. Conventional sensor technology is acceptable for pressure measurement in the low vacuum region, but esoteric technologies developed specifically for high vacuum, eg capacitance manometers, thermal conductivity gauges, and hot and cold cathode ionization gauges, are required for lower pressures. Smart pressure transmitters are revolutionizing industry's approach to pressure measurement. The rationale for replacing conventional transmitters with smart transmitters is discussed herein.
Process Control
Authors: Hahn Juergen , Edgar Thomas F. 
Published: July 2004

AbstractThis article presents the theory and practice of automatic process control and instrumentation, outlining basic concepts of automatic control. The process control hierarchy is described, as is the role played by modern control systems equipment. Because reliable process measurements form the foundation for automatic process control, devices used to measure basic process variables, as well as the practical guidelines for their selections and implementation, are discussed. On‐line process analyzers are also introduced followed by a brief discussion of considerations in the selection and use of final control elements.An overview of the mathematical principles underlying process control is presented and the most common implementations of single‐loop feedback controllers are described. This is followed by a discussion of more advanced control techniques. Since most control methods can be applied to continuous as well as batch processes, concepts related to batch process control are introduced. In a final section, economic aspects of process instrumentation and control systems are discussed.
Process Integration Technology
Authors: Hallale Nick 
Published: July 2004

Abstract
In the past, the major research emphasis in process design has been placed on the analysis, or simulation of processes. The synthesis of processes or process integration has, in comparison, received little attention. This article will discuss the evolution of process integration technology over the past two decades and outlines the problem of chemical process design and then discusses pinch analysis, which developed against the background of the energy crisis of the late 1970s.
This article will describe the state‐of‐the‐art developments that have been made in process integration and that build on the foundations laid by pinch analysis and mass integration. It will describe how the design tools have evolved from purely graphical, thermodynamic approaches to incorporate the latest mathematical optimization techniques. Process integration can now address four main themes: efficient use of raw materials, energy efficiency, emissions reduction, and process operations.
This article ends by describing some of the issues with industrial applications and describes some very successful case studies before considering some of the future developments that can be expected.
Genetic Engineering, Procedures
Authors: Schmidt Francis J. 
Published: July 2004

AbstractThe contemporary meaning of genetic engineering implies a use of the techniques of molecular biology, especially recombinant deoxyribonucleic acid (DNA) techniques, rather than breeding in the formation of new genotypes. Recombinant DNA molecules are composed of two parts: first, a vector where the function is to provide the biochemical functions necessary for replication of the recombinant DNA molecule, and secondly, the passenger DNA which is joined to the vector and is replicated passively under control of the vector. Recombinant DNA technology allows the constructionin vitroof DNA molecules that are not found in nature and the subsequent introduction into organisms, resulting in new genotypes and phenotypes of the recipient. Particularly in plant and animal science, a gene may be introduced into an organism by recombinant DNA technology and the line with the desired properties further manipulated by breeding. Safety regulations have been modified to recognize that no new hazards are created by recombinant DNA research, eg, DNA introduction does not make a pathogen out of a nonpathogen.