bluuebunny/crossref_metadata_2025 huggingface dataset:
Photovoltaic Cells
Authors: Gay Charles F. , Eberspacher Chris
Published: July 2004

Issues such as global warming, ozone depletion, acid rain, safety of nuclear power plants, and disposal of radioactive waste products are prompting broad debate as to the viability of conventional sources of energy on economic and environmental terms. The combination of a rising demand for reliable, low cost energy and this increased awareness of environmental quality issues is creating new business opportunities for photovoltaics, especially in applications without an installed electric utility grid line.

The photovoltaics (PV) industry has been evolving since the 1970s and is rapidly expanding. During the early 1990s, the compound annual growth rate of the PV industry has been greater than 15% with the 1994 worldwide market estimated to be about 68 MW per year; approximately $350 million for PV modules and nearly an equal amount of revenue from the components necessary to make an operational system. Much of this growth is a result of technology cost reduction through economies of scale and evolutionary learning experience as well as market development reflecting the increasing awareness of the versatility, reliability, and economy of PV electric supply systems.

The PV market expansion is being filled primarily by well‐established crystalline silicon technologies, which are low cost, large‐area relatives to integrated circuit technology. Incremental improvements in crystalline silicon technologies are lowering PV costs and fueling further market expansion. However, the most significant growth will occur as a result of the increasing involvement of international financing institutions and participation of utilities as marketing organizations.
Metal Surface Treatments, Pickling
Authors: Hacias Kenneth
Published: July 2004

Pickling of metals and metal alloys involves the use of chemical cleaning agents to remove oxides from metal surfaces. The oxides may be in the form of corrosion by‐products or heat treatment scales. Chemical pickling is an extremely effective and economical method for oxide removal, particularly for intricate shapes not readily cleaned mechanically. The choice of acid or alkali pickling product is generally dictated by the base metal or alloy that is to be cleaned. Sulfuric acid is the most commonly used pickling agent for ferrous metals. Mixtures of acids are often a better choice for nonferrous alloys.
Pilot Plants
Authors: Palluzi Richard P.
Published: July 2004

Pilot plants are a generic term covering numerous types of special equipment and systems designed to support or conduct research activities on a scale larger than glassware in a hood. This article briefly covers some of the principal topics and concerns and provides references for further information. Included are some different methods of categorizing pilot plants as well as information about typical units. The importance of scale‐up and planned experimentation are reviewed. The article discusses some of the more common concerns, highlighting the way pilot plants differ from commercial plants. Subjects include design, costs, schedules, and space. Control and instrumentation are also briefly covered. The importance and difficulty of start‐up is noted as is the difficulty of ensuring safety in such atypical equipment and operations.
Pipelines
Authors: Whaley Thomas P. , Long George M.
Published: July 2004

Pipelines are continuous large‐diameter pipes, usually buried underground, for transporting gases, liquids, or solid slurries over distances ranging from a few to several thousand kilometers. The largest uses are the transport of natural gas or crude oil from producing fields to terminals or processing plants, or petroleum products from oil refineries or natural gas processing plants to distribution points. Pipeline systems in the oil and gas industries consist of small‐diameter gathering pipelines that carry oil or natural gas from producing, wells, and large‐diameter cross‐country pipelines with either compressor stations (for gases) or pumping stations (for liquids) along the route to maintain flow velocities over great distances. Small‐diameter pipe in distribution systems is not part of a pipeline system. Despite great similarities between gas and liquid pipelines in these industries, their regulation has been significantly different. Pipelines are also used to transport anhydrous ammonia, hydrogen, carbon dioxide, molten sulfur, chlorine, nitrogen, oxygen, helium, and other liquid or gaseous chemicals. Freight pipelines transport solids, either as finely divided particles slurried in water or other fluids, or encased in capsules propelled by compressed air or flowing water. Slurry pipelines transport coal, iron ore, phosphate rock, mine‐tailings, municipal wastes, wood fibers, and other finely divided solids suspended in water, the slurry often being dewatered at the terminus. Pipeline transport of materials is probably the safest, least costly, and most environmentally benign of all forms of over‐land transport of materials.
Growth Regulators, Plant
Authors: Cutler Horace G.
Published: July 2004

The arrival of new plant growth regulators on the market in the early 1990s, especially synthetic ones, is in a static state. Many growth regulators continue to be used experimentally, but the transition to approved usage is being delayed for several reasons. On the financial side, a number of mergers, buy‐outs, and other dispositions of chemical companies has led to a decrease in the number of commercial compounds available. Moreover, the cost of registration has prompted some producers to withdraw chemicals from the market. Some older plant growth regulators have undergone several trade name changes, adding confusion to the field.

The ideal plant growth regulator should leave no harmful persistent residue in a finished product or crop and the paradigm compounds are ones that have high specific activity, are target specific, and are environmentally biodegradable. The most acceptable growth regulators appear to be those compounds that already occur in nature and elicit certain desirable responses in economic crops.
Plant Location
Authors: Meissner Roland E.
Published: July 2004

Health and safety of personnel and loss prevention are paramount concerns of the chemical industry. Several industry groups encourage members to improve the management of safety and improve manufacturing procedures and practices to minimize hazards. Moreover, state and federal authorities have legislated improvements for the safety of both employees and the public. Particular emphasis has been given to process safety in the legislation and in industry guidelines, and chemical manufacturers are required to follow detailed steps in ensuring adequate training, comprehensive operating procedures, thorough analysis of processes for hazards and investigation of accidents, diligent maintenance of facilities, well‐developed emergency plans, and self‐audits for compliance. Process safety management, including process production hazards and the various engineering and administrative controls, is discussed. The role of plant location, design and operation of facilities, and hazard prevention are presented, as are safe work practices and hazard analysis.
Fractionation, Plasma
Authors: Foster Peter R.
Published: July 2004

Blood plasma fractionation is a biopharmaceutical manufacturing operation in which high quality, proteinaceous products are prepared for clinical use from human plasma. Products prepared in this manner include albumin, eg, human serum albumin, and plasma protein fraction, for volume and protein replacement in surgery and for the treatment of injury and disease; coagulation factors, eg, Factor VIII and Factor IX Complex, for the prevention and treatment of bleeding disorders; and immunoglobulins, eg, immune serum globulin and immune globulin intravenous, for the prevention and treatment of infectious diseases and immune disorders.

A number of highly integrated bioseparation processes are employed to fractionate human plasma into its different constituents. These range from established cold‐ethanol precipitation technology, devised in the 1940s, to more recently developed solid‐phase adsorption/desorption techniques.

The principal developments since 1980 have been immunoglobulin products for intravenous use, and highly effective technologies for the inactivation of viral contaminants, such as hepatitis viruses and Human Immunodeficiency Virus (HIV), which were associated with earlier coagulation factor preparations.
Plastics Testing
Authors: Furches Barbara J.
Published: July 2004

Plastics testing covers analytical, thermal, physical, and environmental procedures for determining the composition, structure, as well as mechanical and other responses to a variety of environmental conditions of plastic materials. General uses of Fourier transform infrared, nuclear magnetic resonance, Raman, and X‐ray techniques are reviewed and illustrated with specific examples. Developments in neutron and X‐ray scattering techniques, as well as molecular weight determination techniques such as gel‐permeation chromatography and turbidimetric methods, are also covered. Thermal tests, thermogravimetric analysis, differential thermal analysis, differential scanning calorimetry, and dynamic mechanical analysis are all useful for understanding degradation and phase changes in polymers and their influence on material behavior. New techniques of atomic force microscopy and positron annihilation are allowing studies of the microstructure of polymers and free volume determinations. Several mechanical testing techniques are used in plastics for normal quality control testing and initial application screening of polymers. These tests and those used for more fundamental understanding of polymer response to stress, including fracture mechanics procedures, are referenced. Flammability tests commonly used for plastics include oxygen index, flammability ratings, and smoke generation. Work on the use of cone calorimeters to characterize behavior of plastics under fire conditions is also covered. Finally, environmental testing, chemical exposure, weathering, radiation, and biological agents are reviewed. Emphasis is given to test development or applications reported since 1990.
Polyamides, Plastics
Authors: Palmer Robert J.
Published: July 2004

Polyamides (nylons) are important engineering plastics as well as being well known for fiber applications. This article covers the properties, manufacture, processing and use of polyamide plastics together with information on specifications, sales, pricing and suppliers. Materials discussed include nylon‐6,6, nylon‐6, nylon‐6,9, nylon‐6,12, nylon‐11, nylon‐12, nylon‐4,6, amorphous nylon and other semi‐aromatic nylons. Physical properties described are crystallinity, thermal properties, moisture absorption, electrical properties and flammability. Chemical properties are hydrolysis/polycondensation, thermal degradation, oxidation, UV ageing and effect of chemicals and solvents. Manufacture is described including solid state polymerization, compounding, and pultrusion. Compounding also includes a review of additives and modifications covering lubricants, nucleants, stabilizers, impact modifiers, flame retardants, plasticizers, reinforcements, nanocomposites and polymer blends. The following processing routes are detailed: injection molding, extrusion, film, tubing and pipe, monofilament, rods and profiles, wire and cable coating, blow molding, rotomolding, reaction injection molding (RIM), powder coating and also assembly techniques. Uses and automotive, electrical/electronic, consumer and industrial applications are described. A discussion of recycling is followed by a summary of economic aspects including suppliers, sales and pricing. Specifications, standards and quality control are also reviewed with an indication of appropriate test methods.
Plastics Processing
Authors: Xanthos M. , Todd D. B.
Published: July 2004

Processing of plastics comprises a variety of operations involving flow and shaping of polymer melts into finished articles. For thermoplastic resins the most common processing operations are extrusion and molding. In extrusion, solid plastic resin is melted and then shaped in a continuous part of a defined cross‐section by screw‐conveying and forcing the melt to flow through a die. Die forming is used in pipe and tubing, film, sheet, wire, and cable coating. Molding involves such noncontinuous processes as injection molding, blow molding, rotational molding, and compression molding, in which three‐dimensional parts are made in a closed mold. Molded products are solid, hollow, or foamed. Other thermoplastics operations include thermoforming, calendering, and casting. In contrast to thermoplastics, thermosetting resins use low viscosity components which, through chemical reaction, produce the solid part in the mold. Common processing methods for thermoset systems are compression molding, transfer molding, and injection molding. Specialized techniques developed for fiber‐reinforced thermosets include open‐mold processing, pultrusion, resin transfer molding, and reaction injection molding. Specific processing methods for making low density articles from thermoset polyurethanes are described.
Polishes
Authors: Randall Francis J. , Dwyer Seán G.
Published: July 2004

Polishes beautify and protect by coating or refinishing surfaces. Some also clean. Replacing natural waxes with synthetic polymers has improved quality, durability, and convenience. Furniture polishes include liquid or paste solvent waxes, clear or emulsion oils, emulsion waxes, sprays, and impregnated wipes. Each has cleaning, gloss, or durability advantages. Household floor polish trends stress convenience; institutional floor polish trends stress labor reduction through durability or speed. Ingredients include film formers, waxes for repairability, zinc oxide for hardness and removability, and additives for control of leveling or film forming. Some treatments for stone floors modify chemically rather than coat. Car polishes add gloss and remove soil or oxidized paint. Film agents, waxes, or silicones may provide detergent resistance or hide scratches. Industrial metal polishes use abrasives to make surfaces smooth and reflective, and household polishes control tarnish and clean. Gloss and protection are provided by shoe polishes, which are either self‐polishing liquids, emulsion creams, or solvent pastes that differ from paste furniture polishes in dye and wax content. Shoe creams are emulsions of waxes, solvents, and water. Health, safety, and environmental issues include toxicity, slipperiness, and volatile organic compound levels.
Fluorine‐Containing Polymers, Poly(Fluorosilicones)
Authors: Bajzer William X. , Kim Yung K.
Published: July 2004

Poly(fluorosilicones) are siloxane polymers with fluorinated organic substituents bonded to silicon. The combination of fluoroorganic and siloxane properties into one material has many unique applications. The monomer and polymer preparations are reviewed for the manufacture of poly(3,3,3‐trifluoropropyl)methylsiloxane and related poly(fluorosilicones). The polymers and their materials' application properties are discussed with a correlation to chemical structure and stability. The processing, compounding, and curing of the poly(fluorosilicones) into fluids, sealants, rubber, and related applications are described, along with information on safe handling characteristics. Specific examples of applications are covered. An estimation of global capacity is given along with a perspective on market aspects.
Polycarbonates
Authors: Brunelle Daniel J.
Published: July 2004

Polycarbonates are an unusual and extremely useful class of polymers. The vast majority of polycarbonates are based on bisphenol A (BPA) and sold under the trade names Lexan, Makrolon, Calibre, and Panlite. BPA polycarbonates having high glass‐transition temperatures are widely regarded for optical clarity and exceptional impact resistance and ductility at room temperature and below. Other properties such as modulus, dielectric strength, or tensile strength are comparable to other amorphous thermoplastics at similar temperatures below their respective glass‐transition temperatures. Polycarbonates are prepared commercially by two processes: Schotten–Baumann reaction of phosgene and an aromatic diol in an amine‐catalyzed interfacial condensation reaction, or via base‐catalyzed transesterification of a bisphenol with a monomeric carbonate such as diphenyl carbonate. Important products are also based on polycarbonates in blends with other polymers, copolymers, branched resins, flame‐retardant compositions, foams, and other materials. Polycarbonate, produced globally, has been the object of research studies, owing to its widespread utility and unusual properties. This article summarizes the preparation, properties, and utility of polycarbonates.
Fluorine‐Containing Polymers, Polytetrafluoroethylene
Authors: Gangal Subhash V.
Published: July 2004

Polytetrafluoroethylene (PTFE) has a unique position in the plastics industry because of its chemical inertness, heat resistance, excellent electrical insulation properties, and low coefficient of friction in a wide temperature range. This white to translucent solid polymer has an extremely high molecular weight in the 106–107range. It is a highly crystalline polymer and has a crystalline melting point, and its high thermal stability is due to the strong carbon‐fluorine bond, making PTFE a very useful high temperature polymer.

Commercial PTFE is manufactured by two different polymerization processes that result in two different types of chemically identical polymers. Suspension polymerization produces a granular resin, and emulsion polymerization is used to produce coagulated dispersion or stabilized dispersion. Because of its high molecular weight, PTFE melt does not flow and cannot be fabricated by conventional techniques. The suspension polymerized PTFE is usually fabricated by modified metallurgy techniques. Emulsion polymerized, coagulated PTFE is processed by a cold extrusion process; the stabilized dispersions are processed according to latex processing techniques.
Polybutadiene
Authors: Halasa Adel F. , Massie J. M.
Published: July 2004

The discovery of rubbery elastomers based on 1,3‐butadiene and its derivatives was made in 1926. I. G. Farben developed a process to use sodium polymerization on a commercial scale. The resulting polymer, Buna, made from butadiene and natrium, was tested in passenger car tires, and the results were fairly encouraging since it showed equivalent wear properties to natural rubber compounds.

The work on emusion polymerization of butadiene and copolymerization of butadiene and styrene or acrylonitrile began in the 1920s in the United States under the government established Rubber Reserve program. Under this program, Gr‐s and SBR became general‐purpose rubbers even though their tire properties were inferior to natural rubber compounds. Great improvements were made in the emulsion polymerization of 1,3‐butadiene and isoprene, especially with the discovery of chain‐transfer agents used for molecular weight control. Nevertheless, the search for a natural rubber replacement continued in many research laboratories worldwide especially in the United States.
Fibers, Polyester
Authors: Hansen S. M. , Sargeant P. B.
Published: July 2004

Polyester fiber is the largest volume, most versatile synthetic fiber in the world. Useful textile fibers of poly(ethylene terephthalate) (PET) were invented in the 1940s and commercially introduced by Du Pont and ICI in the 1950s. A broad range of PET processing options allows the fiber to be engineered for a variety of uses by modifying the filament size, cross‐sectional shape, polymer molecular weight, tensile strength, composition, dyeability, luster, and color, as well as other fiber properties. PET is produced by ester interchange of dimethyl terephthalate and ethylene glycol to form monomer, or by direct esterification of terephthalic acid with ethylene glycol to form oligomer. The low molecular weight monomer or oligomer is polycondensed at high temperature and reduced pressure to form PET polymer.

Polyester is melt‐spun over a wide range of spinning speeds depending on the desired use. The mechanical and thermal properties of PET fiber are affected by the degree of molecular orientation and crystallinity, which depend on the fiber formation process used. At low spinning speeds, fibers are usually further drawn to obtain useful tensile properties. At high spinning speeds, useful PET yarns can be obtained directly. Additional processing steps, including drawing, thermal treatment, texturing, and others, significantly influence the fiber physical properties and applications.
Polymers Containing Sulfur, Polysulfones
Authors: El‐Hibri M. Jj
Published: July 2004

This article discusses the synthesis, properties, fabrication, and uses of aromatic polysulfones. These polymers are a class of high performance amorphous thermoplastics characterized by high glass‐transition temperatures, good mechanical strength and stiffness, and excellent thermal and oxidative resistance. They are used in a broad range of engineering applications and continue to find new uses as demands for high temperature plastic materials proliferate. The characteristic structural feature of these polymers is the presence of the para‐linked diphenylsulfone group as part of the backbone repeat unit. Emphasis of the discussion is placed on the three commercially available polysulfones, ie, those based on the polycondensation of 4,4′‐dihalodiphenylsulfone with bisphenol A, 4,4′‐dihydroxydiphenylsulfone, and 4,4′‐dihydroxydiphenyl, respectively. Polymerization techniques discussed include nucleophilic and electrophilic polycondensation routes. Property discussions touch on structure and property relations, thermal, physical, and mechanical properties, as well as other performance characteristics. Blendability of polysulfones with other polymers is also briefly discussed. Applications and uses for polysulfones are described as they pertain to specific resin performance features. Also included is information about commercial sources and costs for these materials.
Polyhydroxy)benzenes
Authors: Leston Gerd
Published: July 2004

This article describes the tri‐, tetra‐, penta‐, and hexahydroxybenzenes. The tetra‐, penta‐, and hexahydroxybenzenes are also referred to as benzenetetrols, benzenepentol, and benzenehexol, respectively, and the trihydroxybenzenes are more familiarly known by their trivial names, ie, pyrogallol (or pyrogallic acid), hydroxyhydroquinone, and phloroglucinol, for the 1,2,3‐, 1,2,4‐, and 1,3,5‐isomers, respectively. Included are their syntheses, manufacture where applicable, and occurrence. Physical properties, analyses, chemical properties, uses, and toxicity data are described. The chemistry of the (polyhydroxy)benzenes is presented as is that of their derivatives. Related compounds having the basic structure of the various (polyhydroxy)benzenes are also described. Included are their occurrence and chemical and physiological properties. Most of the physiological activities and uses of the (polyhydroxy)benzenes are attributable to their oxidation–reduction potentials; these compounds are strong reducing agents, useful in photographic developers, photosensitive compositions, hair dyes, and chemical analyses. The benzenepolyols and their derivatives have found use in virtually all phases of chemistry: synthesis, antioxidants, heat and light stabilizers, pesticides, in polymers, resins, and adhesives, pharmaceuticals, cosmetics, and food additives, etc.
Polypropylene
Authors: Lieberman Richard B.
Published: July 2004

Polypropylene is one of the most widely used thermoplastics, accounting for one‐sixth of total consumption. Many automobiles, textile appliances, and other everyday items contain substantial amounts of these polymers. The ability to manufacture a broad variety of polypropylenes having properties tailored for specific applications is the primary factor in its widespread use. Comonomers, usually ethylene, are often used to provide impact‐modified or lower melting polymers. The types of polymers produced, processing methods, and end use are discussed.

Highly stereoselective Ziegler‐Natta catalyst systems are the basis for all propylene polymerization processes. The development of these catalysts, from the early TiCl3systems to the modern, high yield MgCl2‐supported systems, including polymerization mechanisms, is discussed. These catalysts enabled the evolution of these polymerization processes from the early slurry process, to the current liquid monomer or gas‐phase processes. In the future, metallocene catalysts may provide further commercial advances. The Spheripol and Unipol processes are the most notable of the many processes discussed. The large expansion in polypropylene production in the late 1980s was facilitated by the availability of this newer, less costly technology. This expansion, well in excess of growth in consumption, caused a dramatic reduction in polypropylene prices in the 1990s. This expansion was most dramatic in the Far East, where few polypropylene plants existed outside Japan before 1985.
Fluorine‐Containing Polymers, Polychlorotrifluoroethylene
Authors: Millet G. H. , Kosmala J. L.
Published: July 2004

Polychlorotrifluoroethylene (PCTFE) is typically manufactured in a suspension or emulsion polymerization process under relatively mild conditions followed by work‐up procedures, primary coagulation, and washing, to remove residual impurities from the polymer. The resulting fluoropolymer is a high molecular weight fluoroplastic with outstanding thermal and chemical resistance properties. Typical use temperatures range from −240 to 200C; contact with halogenated solvents, ethers, and esters should be avoided. The polymer is supplied in either powder or pellet forms, suitable for a variety of plastic melt processing techniques such as compression and injection molding or extrusion processes. The processing temperatures required are usually above 275C, and chrome‐plated equipment should be employed. The molded or extruded parts can be further refined by a variety of machining processes. This specialty plastic exhibits a combination of unique physical properties that include ultralow moisture vapor transmission and outgassing, oxygen compatibility, cryogenic temperature capability, electrical insulation, resistance to cold flow, good radiation resistance, and low coefficient of thermal expansion.
Polyethers
Authors: Owens Kathryn , Kyllingstad Vernon L.
Published: July 2004

Six commercially produced largely amorphous polyether elastomers are described. These are polyepichlorohydrin, poly(epichlo‐ rohydrin‐co‐ethylene oxide), poly(epichlorohydrin‐co‐allyl glycidyl ether), poly‐ (epichlorohydrin‐co‐ethylene oxide‐co‐allyl glycidyl ether), poly(propylene oxide‐co‐epichlorohydrin‐co‐allyl glycidyl ether), and poly(propylene oxide‐co‐allyl glycidyl ether). Structure and properties including molecular weight and solution behavior for the raw polymers are discussed. Laboratory and commercial prepayration of the polymers are described. Large‐scale polymerization employs a continuous process with the reactants either in solution or as a slurry. Mixing and milling procedures are described in the commercial processing and fabrication section. Compounding information including the use of curing systems, stabilizers, antioxidants, fillers, and plasticizers is presented as well as physical properties and uses of vulcanizates of these polymers. Health and safety considerations pertaining to handling of the constituent monomers, curing systems, and raw polymers are discussed. Economic aspects are described.
Polymers
Authors: Rosen Stephen L.
Published: July 2004

Polymers are the materials from which plastics, rubbers, and most fibers, surface coatings, and adhesives are made. Biopolymers are important constituents of living organisms. Polymers are classified as thermosets or thermoplastics according to their response to temperature, as addition or condensation polymers according to their mode of synthesis, or as linear, branched, or cross‐linked according to their molecular structure. The microscopic structure of a polymer ultimately determines its macroscopic properties. Important structural features include molecular weight, stereoisomerism, and degree of crystallinity. The glass‐transition temperature and crystalline melting point are key parameters in determining a polymer's applications. The structure of polymer molecules is determined by the polymerization mechanism, either step‐growth (condensation) or chain‐growth (addition). Step‐growth polymerizations generally require high conversions and a close approach to stoichiometric equivalence to achieve high molecular weights. Free‐radical addition is used to manufacture a wide variety of polymers through bulk, solution, suspension, and emulsion processes. Ionic addition permits the synthesis of block copolymers and polymers of uniform molecular weight. Heterogeneous addition (Ziegler‐Natta) polymerization provides control of the steric structure of the polymer.
Polyesters, Unsaturated
Authors: Nava Hildeberto
Published: July 2004

Unsaturated polyester resins have been used commercially since the 1940s, establishing markets for reinforced composite plastics derived from combinations with glass‐fiber reinforcements. The availability of a wide variety of raw materials has encouraged the emergence of a diverse range of resins specifically tailored for many unique products. Fiberglass‐reinforced plastics (FRP) technology facilitates the production of large fabricated products, such as chemical and petroleum storage tanks, and a wide range of marine craft, where low cost ambient processing provides competitive advantages. The technology has also evolved for high temperature automatic molding of high volume body components used for automobiles, trucks, and recreation vehicles. Polyester resins are also used extensively in highly filled cast products for kitchen and bathroom countertop applications; polyester polymer concrete provides corrosion‐resistant surfacing for highways and bridges. High performance resins are formulated to provide optimal corrosion and thermal performance in composite products designed for the chemical process industries. Under the mandates of the U.S. Clean Air and Clean Water Regulations, FRP pipe has emerged as a cost‐effective solution to upgrade inner‐city sewer systems, and FRP duct and scrubber systems are used widely in the pulp, paper, and electrical power industries to contain noxious emissions.
Polyisoprene
Authors: Senyek Michael
Published: July 2004

Ever since a syntheticcis‐1,4‐polyisoprene with the structure and properties of natural rubber was prepared in 1954 with the then newly discovered Ziegler catalyst, synthetic polyisoprene has been an important elastomer. Various catalysts have been used for synthesizing polyisoprenes, and the two commercially important systems are Ziegler‐Natta and anionic. The manufacture ofcis‐1,4‐polyisoprene and its compounding into formulations useful in making finished goods and articles are discussed. World plant capacities and estimated production figures forcis‐1,4‐polyisoprene are given, along with current polymer cost.trans‐1,4‐Polyisoprene is produced commercially only in Japan. Some of the specifications forcis‐1,4‐polyisoprene (Natsyn) made by The Goodyear Tire & Rubber Co., the sole United States producer, include volatile matter, extractables, ash, and Mooney viscosity. The principal use forcis‐1,4‐polyisoprene is in tires and tire products, and fortrans‐1,4‐polyisoprene is in golf ball covers and orthopedic devices.
Polyaluminum Chlorides
Authors: Siefert Kristine S.
Published: July 2004

Aluminum chloride hydroxide, AlCl(OH)2, AlCl2(OH), products, commonly known as polyaluminum chlorides (PAC), are used for a wide variety of industrial applications. Other names for PAC are basic aluminum chloride, polybasic aluminum chloride, aluminum hydroxychloride, aluminum oxychloride, and aluminum chlorohydrate. The presence of polymeric, aluminum‐containing cations, the distribution of which can differ greatly, typifies PAC products. Commercially, PAC has been used in water and wastewater treatment in Japan, the former USSR, and Europe since about 1970, and in the United States since the early 1980s. Aluminum chlorohydrate, Al2Cl(OH)5, a specialty PAC product, has been utilized as an antiperspirant for over 50 years. Physical and chemical properties of the numerous PAC products can vary considerably. PAC products are usually aqueous solutions, although solid products are also sold. Solutions range from colorless to amber and from clear to hazy in appearance. A generic manufacturing process for PAC involves the addition of base to aluminum chloride solution. A common process for the manufacture of aluminum chlorohydrate involves the addition of metallic Al to aluminum chloride. Liquid polyaluminum chloride is acidic and corrosive to common metals. Suitable materials for construction of storage and handling facilities include synthetic rubber‐lined steel, corrosion‐resistant fiber glass‐reinforced plastics (FRP), ceramics, tetrafluoroethylene polymer (PTFE), and others. Polyaluminum chloride products used in the treatment of potable (drinking) water must be approved by the National Sanitation Foundation (NSF). Aluminum chlorohydrate for topical use as an antiperspirant is regulated by the FDA.
Polymers, Environmentally Degradable
Authors: Swift Graham
Published: July 2004

Environmentally degradable polymers are a new technology being developed in response to polymer waste‐management, effects of which are threatening to consume valuable landfill sites and are detracting from the aesthetics of land‐ and seascapes. These polymers are one of a range of technologies that are addressing the problem; others include recycle, incineration, and continued landfill. Environmentally degradable polymers include water‐soluble polymers and plastics and degrade by oxidation, hydrolysis, irradiation (photodegradation), and biological pathways. The principal opportunities for this technology are in the niche markets for plastic used in food packaging, agriculture, hygienic products, and other applications with difficult‐to‐recover options; and for water‐soluble polymers in general, which are not sufficiently readily recoverable for one of the alternative disposal technologies to be of value.
Polychloroprene
Authors: Witsiepe W. K.
Published: July 2004

Polychloroprene has been in commercial use for over 60 years, but continues to be the elastomer of choice for dynamic applications requiring moderate heat and oil resistance, or where long‐term environmental resistance is required. The material is manufactured by emulsion polymerization of 2‐chloro‐1,3‐butadiene. The properties of the product can be optimized for specific end uses by selection of polymerization conditions, by use of comonomers such as 2,3‐dichlorobutadiene and methacrylic acid, and by choice of the method used to control molecular weight. The kinetics of the polymerization process and the structure of the polymer have been studied in detail and related to polymer properties. Commercial products vary widely in properties depending on the intended end use and the details of the manufacturing process. Tough crystalline or ionomeric polymers are preferred for adhesive applications, whereas softer, more flexible polymers are preferred for mechanical goods applications. The latter polymers may be compounded and fabricated by substantially all the techniques used for manufacture of rubber goods by molding, extrusion, or calendering operations. Lattices are used for various bonding and adhesive applications as well as for dipped goods requiring toughness in the unreinforced film.
Potassium
Authors: Chiu Kuen‐Wai
Published: July 2004

Potassium, the third element in the alkali metal series, is manufactured by a reduction process using sodium and potassium chloride, operated at high temperature. Sodium chloride is the by‐product.

Potassium is itself a powerful reducing agent and can serve as an electron source for many chemical reactions. It forms liquid–metal alloys with other alkali metals. The potassium–sodium liquid alloys are ideal for use as heat‐transfer, electrical contact, and hydraulic fluids.

Commercially important potassium derivatives prepared from potassium metal include potassium–sodium alloys, alkoxides, amides, hydride, graphite, and superoxide. Most are utilized as reducing agents. A potassium–sodium dispersion provides higher reaction surface and allows reduction at lower temperatures than the individual metals. Potassium alkoxides are strong, nonnucleophilic bases that have good solubilities, selectivities, and stabilities, and are ideal for deprotonation reactions. Potassium graphite, an intercalation compound, can serve as a solid reducing agent. Potassium superoxide, a radical anion, is a strong oxidizing agent, generating oxygen in contact with moisture and carbon dioxide.
Fluorine Compounds, Inorganic, Potassium
Authors: Papcun John R.
Published: July 2004

The two stable forms of potassium with fluorine of commercial significance are the normal fluoride and potassium bifluoride. Potassium fluoride is used in the manufacture of silver solder fluxes and in fluxes for various metallurgical operations. Polyurethane foams can be formed with KF and it is used as a catalyst for the reaction of adiponitrile carbonate and a polyester polyol. Potassium bifluoride is used in the electrolyte for cells in fluorine manufacture, and fluxes for a wide variety of metal joining applications utilize KHF2, usually in combination with potassium pentaborate, boric acid, and other fluorides and chlorides. Physical and chemical properties are discussed.
Powder Metallurgy
Authors: Johnson Peter K.
Published: July 2004

Johnson, Peter K. (Metal Powder Industries Federation, APMI International). Powder metallurgy uses metal powder as the raw material to manufacture products, especially precision metal shapes and parts. The process is cost effective in producing simple or complex parts at or very close to final dimensions. These parts are finding increasing consumer and industrial applications in automobile engines and transmissions, aerospace hardware, home appliances, power tools and hardware, computer disk drives, and surgical implements.

Powder metallurgy products include tungsten lamp filaments, self‐lubricated bearings, various magnet, tools, metal‐matrix composites, and electrical components. Use of the technology continues to grow in importance. Superalloys intermetallics, and nanoscale powders are all formed from powder techniques. Processes for producing metal powders are reviewed, and powder characteristics, are discussed.

Basically a chipless metalworking process, powder metallurgy typically uses more than 97% of the starting raw materials in the finished part. The new‐shape advantage makes it a process of choice for precision metal components at reduced manufacturing costs. Various production processes for consolidating metal powders into shapes such as traditional compacting and sintering, rapid solidification, cold and hot isostatic pressing, metal injection molding, powder forging and rolling, and spray forming are reviewed.
Printing Processes
Authors: Taggi Arthur J. , Walker Peter
Published: July 2004

The role of chemical technology in printing processes is changing. These changes are driven by cost, convenience, and environmental pressures. Rapid advances in alternative media and computer technology are enabling the incorporation of electronic processes into the printing workflow to meet industry cost and performance needs. Elements of the printing process from image creation, capture, assembly, storage, movement, approval, duplication, output, and distribution are examined. The continuing role of chemical printing processes such as lithography, flexography, letterpress, screen printing, and thermal printing, as well as the various media and inks employed, is described. The opportunities provided by electronic technology are also presented. The newer electronic digital processes involve consumable materials that are based on chemical systems more suited to the changing needs of the printing industry. The new digital systems capabilities are discussed in terms of their impact on industry practices and workflow. Technologies that are changing the nature of the printing industry include thermal imaging, electrophotography, and ink‐jet printing.
Graphite, Processing Artificial
Authors: Turk D. L.
Published: July 2004

Calcined petroleum coke arrives at the graphite manufacturer's plant in particle sizes ranging typically from dust to 50–80 mm diameter. In the first step of artificial graphite production, the run‐of‐kiln coke is crushed, sized, and milled to prepare it for the subsequent processing steps. The size of the largest particle is generally set by application requirements. The manufacturing process begins with the mixing operation. The purpose of mixing is to blend the coke filler materials and distribute the pitch binder over the surfaces. The intergranular bond ultimately determines the properties and structural integrity of the graphite. Thus the more uniform the binder distribution throughout the filler components, the greater the likelihood for a structurally sound product. After the forming operation, the purpose of which is to compress the mix so that pitch‐coated filler particles and flour are in intimate contact, in the next stage, the baking operation, the product is fired to 800–1000°C. One function of this step is to convert the thermoplastic pitch binder to solid coke. Another is to remove most of the shrinkage in the product associated with pyrolysis of the pitch binder at a slow heating rate. This procedure avoids cracking during subsequent graphitization. A variety of baking furnaces are in use. One common baking facility is the pit furnace, so named because it is positioned totally or partially below ground level to facilitate improved insulation. Another common baking facility is the so‐called ring furnace. Two equal rows of pit furnaces are arranged in a rectangular ring. A more recent development is the carbottom furnace, which is mounted on wheels and movable. The method used to improve those properties necessary for many high performance applications of graphite is impregnation with coal‐tar or petroleum pitches. Graphitization is an electrical heat treatment of the product to ca 3000°C. The purpose of this step is to cause the carbon atoms in the petroleum coke filler and pitch coke binder to orient into the graphite lattice configuration, producing graphite with intermetallic properties useful in many applications. In the temperature range of 1500–2000°C, most petroleum cokes and coal‐tar pitch cokes undergo an irreversible volume increase known as puffing, associated with thermal removal of sulfur. Depending on particle size and on the product size, heating rates must be adjusted in the puffing range to avoid splitting the product. Fortunately, the use of puffing inhibitors has eased the problem.
Fine Chemicals, Production
Authors: Pollak Peter
Published: July 2004

Fine chemicals are low volume, high priced chemical intermediates and bulk active ingredients primarily used in the preparation of pharmaceuticals and agrochemicals, but also in other specialties, such as dyestuffs and pigments, flavors and fragrances, and food and feed additives. In contrast to specialty chemicals, these are mostly sold within the chemical industry and according to specifications rather than performance criteria. Fine chemicals typically are manufactured in multipurpose plants starting from commodity chemicals and involving several distinct synthetic steps. The core production unit is a train of one or more modules where several fine chemicals can be produced in compaign fashion in the same production train. A complete plant also contains other facilities. Research and development play an important role, as does plant design.
Product Liability
Authors: Twerski Aaron
Published: July 2004

This article charts the changes of American products liability laws. It examines such topics as implied warranty of merchantability, prima facie case and affirmative defense, as well as the Second and Third Restatements, defining in the process such terms as defect, proximate cause, foreseeability, and the role of plaintiff conduct. Actual liability cases are used to illustrate the discussion.
Propylene
Authors: Calamur Narasimhan , Carrera Martin
Published: July 2004

Propylene is an important industrial chemical used as a feedstock in the production of polypropylene, acrylonitrile, propylene oxide, 2‐propanol, alkylated fuels, and other chemicals. It is obtained from steam cracking in pyrolysis furnaces in olefins plants and in refinery catalytic‐cracking reactors. Propane dehydrogenation is a new production technology not yet exploited on a large scale. Distillation in multitray columns yields purities in excess of 99.5 wt %. The physical and chemical properties of propylene are well characterized. Under ambient conditions, it is a colorless gas and has anesthetic properties at high concentrations. Propylene is usually transported in the liquid state at high pressures. Proper precautions must be taken when handling propylene.
Sugar, Properties of Sucrose
Authors: Colonna William J. , Samaraweera Upasiri
Published: July 2004

Sucrose is a nonreducing disaccharide produced by crystallization from syrups derived from processing sugarcane and sugarbeets. World production averaged\documentclass{article}\usepackage{amssymb}\pagestyle{empty}\begin{document}${{\rm{\sim }}113}$\end{document}million t/yr between 1990 and 1995, with\documentclass{article}\usepackage{amssymb}\pagestyle{empty}\begin{document}${{\rm{\sim }}65{\%}}$\end{document}derived from cane. Sucrose's most important properties are its water solubility and its sweetness. The latter is influenced by temperature, pH, etc, and is synergistic with other sweeteners. Sucrose is destroyed by strong oxidizing agents, and extremes of pH. Optical rotation, enzymatic analysis, and instrumental methods are used for sucrose quantitation. Sucrose is the leading food additive and contributes sweetness, mouthfeel, texture, body, humectancy, and appearance to foods. Sugar also enhances the taste of foods and minimizes undesirable flavors.

Esters, ethers, acids, polyurethanes, and other polymers are synthesized from sucrose. Sucrose esters are used as food emulsifiers, fat mimetics, detergents, bleach boosters, and antibacterials. Selective chlorination converts sucrose into sucralose, a noncaloric, high intensity sweetener. Alcohols, organic acids, antibiotics, dextrans, levans, and noncariogenic sweeteners are derived from sucrose by fermentation. Sucrose is used in medicines to mask unpleasant tastes, in tablet formulations, and to promote wound healing. Sucrose derivatives are used in treating ulcers and as antitumor agents. At current consumption rates, dietary sucrose promotes dental caries, but does not cause diabetes, hyperactivity, obesity, or heart disease.