bluuebunny/crossref_metadata_2025_split huggingface dataset:
Thermoforming
Authors: Throne James L. 
Published: October 2003

AbstractThermoforming is a generic term for the art and science of forming commercial products by heating plastic sheet to a pliable state, pressing the sheet against a cool mold, holding the formed sheet against the mold until cool, and trimming the formed part from the web or skeleton surrounding it. About 4.55 million metric tons of product are thermoformed worldwide at a value of about US$35,000 million. Thermoforming is characterized as capable of forming many polymers, of forming large surface area‐to‐wall thickness parts of forming parts against single‐surface molds that can be made of many materials, and of using moderate forming temperatures and pressures. Thermoforming does not produce a part with walls of well‐controlled, uniform thickness, and produces trim, web, or skeleton that usually must be recycled to achieve competitive economics.Thin‐gauge thermoforming represents about 75% of the product volume, with the major products being packaging and disposable containers. Heavy‐gauge thermoforming represents about 25%, with the major products being permanent or industrial products.A typical thermoforming machine consists of a sheet‐handling system, at least one heating station, a forming press, a vacuum system, and a control system. A trim station may or may not be integral to the machine. In addition, the machine may have sheet‐prestretching capability, a pressure system, and mold‐cooling capability. Cast or machined aluminum is the common mold material. Plugs or mechanical pushing devices are usually made of lower‐thermal‐conductivity materials such as molded nylon, epoxy, wood, or syntactic foam.Technically, thermoforming is three essentially separate sequential steps: sheet heating, stretching, and trimming. Radiation is the primary mode of sheet heating. Efficient heating relies on the specific absorption characteristics of long infrared wavelength energy by the polymer. Sheet stretching is biaxial deformation of the nonisothermal rubbery elastic or viscoelastic membrane achieved through differential pressure across the sheet surface. Trimming is mechanical cutting or breaking of the cooled plastic. This is usually achieved with steel rule dies, forged dies, or for heavy‐gauge parts, with bandsaws or numerically controlled multiaxis routers.Of late, twin‐sheet forming has become economically competitive. Improved process controls are being used to form parts from highly filled and reinforced polymers.
UV Stabilizers
Authors: Cangelosi Frank A. , Davis Leonard H. , Gray Robert L. , Stretanski Joseph A. , Jakiela Dennis J. 
Published: October 2003

AbstractThe beneficial effects of the major classes of light stabilizers are reviewed from a theoretical perspective as well as through practical application examples. The use of UV absorbers, hindered amine light stabilizers, other stabilizer types, and combination systems to reduce aesthetic as well as physical property deterioration due to UV exposure is discussed. Continued research on both the theoretical and practical aspects of polymer light stabilization will provide the basis for the successful development of new UV‐stabilized plastics and coatings formulations.
Vibrational Spectroscopy
Authors: Hsu Shaw Ling 
Published: October 2003

AbstractThis article presents various applications of vibrational spectroscopy for analysis of polymer structure. The relative merits of vibrational spectroscopy versus other techniques for characterization of polymer structure are discussed. Special emphasis is given to analysis of chain configuration, conformation, interchain interactions, crystallization behavior, and crystalline region size. Experimental data combined with data provided by normal coordinate analysis were utilized in analysis of spectroscopic features associated with disordered chains. Specialized topics such as amount of free volume, phase transformation, microspectroscopy, segmental orientation, and surface analysis are presented. Analysis of structural dynamics using double modulation spectroscopy and time resolved spectroscopy is also addressed.
Vinyl Alcohol Polymers
Authors: Marten F. L. 
Published: October 2003

AbstractPoly(vinyl alcohol) is a highly crystalline polyhydroxy polymer produced by the hydrolysis of poly(vinyl acetate) because the vinyl alcohol monomer is not available. The polymer is water‐soluble and possesses excellent tensile strength, abrasion resistance, and superior oxygen‐barrier properties. PVA has excellent emulsification and protective colloid properties. Solvent, oil, and grease resistance are matched by few other polymers.Poly(vinyl alcohol) undergoes chemical reactions in a manner similar to other secondary polyhydroxy alcohols, and is fully biodegradable. The polymer is considered a nonhazardous material according to the American Standard for Precautionary Labeling of Hazardous Industrial Chemicals.Industrial applications of poly(vinyl alcohol) are all based on and limited by the use of water solutions. The polymer is not considered thermoplastic as the degradation temperature is below the melting point.Poly(vinyl alcohol) is commercially available in granular and powdered form. Grades include both fully hydrolyzed and partially hydrolyzed products. A wide variety of molecular weight and hydrolysis is commercially available.Major end uses include textile sizing, adhesives, protective colloid for emulsion polymerization, paper coating, cement and mortar additive, poly(vinyl butyral), fibers, and films.
Vinyl Chloride Polymers
Authors: Allsopp Michael W. , Vianello Giovanni 
Published: October 2003

AbstractThis article covers the uniqueness and versatility of this high tounage thermoplastic. The unique morphology of PVC is covered in detail and related to both its polymerization and production processes and also to its subsequent processing at the customer end. Each of the main polymerization processes of suspension, mass, and emulsion are described in detail with particular emphasis on how the morphology of each different product is created. Other aspects such as environmental protection, quality and testing, processing, and economic aspects complete the story of this fascinating polymer.
Vinylidene Chloride Polymers
Authors: Wessling R. A. , Gibbs D. S. , Obi B. E. , Beyer D. E. , DeLassus P. T. , Howell B. A. 
Published: October 2003

AbstractVinylidene chloride is a versatile monomer used primarily for making vinylidene chloride copolymers. These copolymers are mostly used in food packaging to provide a good barrier to mass transport. Most applications rely on the low permeation of oxygen, carbon dioxide, and water vapor. However, the polymers have also been shown to have good barrier to flavors and aromas. Thus, a barrier layer of one of these copolymers in a package structure not only prevents spoilage of the food item but prevents flavor “scalping” on the supermarket shelf. These copolymers are available in three forms. First, resin for extrusion into film or sheet represents the largest segment. This includes monolayer and coextruded film and coextruded sheet. Second, a number of emulsion resins are used for solution applications. A thin layer is coated onto a substrate. Third, copolymer latexes are used for paper coatings, etc. The coatings from solution or latex dry clear. Vinylidene chloride homopolymer does not have commercial application because its melting temperature is too high to permit extrusion without degradation, and it does not dissolve in a suitable solvent for coating.
Viscoelasticity
Authors: McKenna Gregory B. 
Published: October 2003

AbstractA broad view of polymer viscoelasticity is presented. The article first discusses the basic definitions of stress and strain and the material modulus and compliance properties that relate the two in linear elasticity theory. The time‐dependent analogues in viscoelasticity are presented. The beginnings of polymer viscoelasticity concepts are then presented by building mechanical analogues of springs (elastic) and dashpots (viscous) elements that can capture the general features of polymeric behavior. A brief discussion of the elastic–viscoelastic correspondence principle is also provided. The general viscoelastic response of polymeric materials is presented by emphasizing the amorphous state and how the isochronal modulus changes with temperature. This is analyzed within the context of time–temperature superposition ideas and the Williams, Landel, and Ferry equation. In particular, it is interesting to divide the behavior into that below and far above the glass‐transition temperature. In the former case the local segmental motions of the polymer dominate behavior, while in the latter the long‐chain nature of the polymer dominates behavior. Molecular rheology ideas are briefly presented where the idea of the chain length or molecular weight dependence of the viscosity is introduced. This is extended by considering the scaling of viscosity and plateau modulus due to concentration as well as the introduction of time–concentration superposition principles similar to time–temperature principles.The nonlinear rheological response of polymers far above the glass‐transition temperature is handled within a combined framework of the phenomenological K‐BKZ model and the Doi–Edwards (DE) tube model, which is based on the reptation ideas of de Gennes. The K‐BKZ framework is particularly useful because it looks much like time‐dependent finite elasticity theory that has been widely and successfully applied to rubber network polymers. Extensive discussion is presented of the comparison between theory and experiment of both K‐BKZ and DE models for polymer nonlinear viscoelastic behavior in the melt and solution states. Below the glass‐transition temperature, measurements of the nonlinear viscoelastic response are examined within the framework of the BKZ model, but also considering compressibility. Emphasis is given to torsional experiments in which both the torque and the normal force are measured. This exposition is followed by a description of several other nonlinear viscoelastic models that have been used for describing solid polymers. This article ends with a brief mention of plasticity models for the behavior of polymeric solids.
Weathering
Authors: Searle Norma D. 
Published: October 2003

AbstractThe irreversible changes in chemical and physical properties of polymeric materials exposed to the environment are caused by the combined action of all weather factors, including solar radiation, heat, moisture, oxygen, and atmospheric pollutants. However, the actinic radiation of the sun absorbed by materials is the critical factor. It initiates the chemical reactions that lead to degradation through its bond breaking capabilities. The wavelength specificity of degradation, and its material dependency are illustrated by the activation spectra of various types of polymers. The contributions of the other major environmental factors to weathering and various types of outdoor weathering tests are described. The significant advances in development of weatherable polymeric materials have increased the need for more rapid evaluations by both outdoor and laboratory accelerated tests. Their validity depends on how well they simulate the effects of exposure to end‐use environments in terms of failure modes, mechanism of degradation, and stability rankings of materials. The most important factor in good correlations between laboratory accelerated and outdoor weathering tests is adequate simulation of the spectral power distribution of the natural source over the full range of actinic wavelengths. The types commonly used in laboratory accelerated devices are compared with solar radiation and the effects of their deviations in the uv and visible regions are discussed. The effect of increased stress levels of irradiance, temperature, and moisture on acceleration factors and on correlation with natural weathering tests are described. Techniques for predicting lifetimes under natural weathering based on laboratory accelerated tests are reviewed.
X‐ray Microscopy
Authors: Ade H. 
Published: October 2003

AbstractDuring the last few years near edge x‐ray absorption fine structure (nexafs) spectroscopy/microscopy has evolved into a useful characterization tool for polymer science, providing quantitative compositional mapping with minimal radiation damage at a spatial resolution of presently about 40 nm. This article reviews the spectroscopic principles of nexafs, discusses some polymer nexafs reference spectra to illustrate the underlying utility of nexafs spectroscopy to nexafs microscopy, and provides an overview of the state‐of‐the‐art of x‐ray microscopy instrumentation. Applications of nexafs microscopy are wide ranging and include mapping the composition of polymer thin films and their surfaces, as well as the composition of ultrathin sections of bulk materials ranging from polymer blends to multilayers. To date, nexafs microscopy is still a specialized technique that requires powerful synchrotron radiation sources, similar to established polymer science tools such as neutron and x‐ray small‐angle scattering and reflectivity.
Engineering Thermoplastics, Overview
Authors: Garbassi Fabio , Po Riccardo 
Published: October 2003

Abstract
This article provides a first key of access to engineering polymers. There is a compilation of materials classified as engineering thermoplastics, eg, cyclic olefin copolymers, syndiotactic polystyrene, acetal resins (polyoxymethylene), polyester resins [ie, poly(ethylene terephthalate), poly(butylene terephthalate), and poly(ethylene naphthalate)], polyarylates, liquid crystal polymers, poly(phenylene ether), polycarbonate, aliphatic and aromatic polyketones, acrylic resins, poly(phenylene sulfide), polysulfones, styrene copolymers, aliphatic and aromatic polyamide resins, polyimides, polyamide imide, polyphthalamide, polyetherimide, and fluoropolymers (polytetrafluoroethylene, ethylene–tetrafluoroethylene copolymers, fluorinated ethylene–propylene copolymers, perfluorovinylether–tetrafluoroethylene copolymers). For engineering thermoplastics in general, this article provides a short development history and a discussion of industrial production methods, physical, thermal, mechanical, electrical, and chemical properties, processing technologies, and some applications. Because property values can vary in a wide range, representative figures are reported, mostly from commercial data sheets compiled by producers; these data are available on‐line and are continuously updated. Some of the main properties are compared, on the frame of interpolymer competition.
Laser Light Scattering: Some Recent Developments
Authors: Chi Wu , Xiangjun Gong 
Published: October 2003

AbstractThis review summarizes some recent developments in the characterization of some special intractable macromolecules in solution by a combination of static and dynamic laser light scattering (LLS). Since both static and dynamic LLS are theoretically well established, we have limited this review on experimental details, such as the design of a high temperature LLS spectrometer, the clarification of polymer solutions, complementary apparatuses such as a novel differential refractometer, and portable particle sizer.
Ethylene Polymers,HDPE
Authors: Benham Elizabeth , McDaniel Max 
Published: October 2003

AbstractPolyethylene (PE) is the most widely used plastic throughout the world, and high density polyethylene (HDPE) is the most widely used type of polyethylene. It was invented independently in the early 1950s in three different laboratories across the world. Commercial catalytic processes were quickly developed based on three different transition metals: chromium, molybdenum, and titanium. Today hundreds of different grades of HDPE are manufactured by several different commercial processes worldwide to meet the demands of applications too numerous to describe completely. HDPE properties can be made to vary widely for these specialized applications by manipulating its molecular structure, such as the molecular weight (MW), the MW distribution, the amount, type and placement of short‐chain branching, the end group composition, and the degree of long‐chain branching. These affect the stiffness of the polymer, the gloss or clarity, the impact, puncture and tear resistance, chemical resistance, electrical insulation properties, molding characteristics, and tensile properties. Common uses for HDPE include food packaging, bottles, bags, drums, fuel tanks and other automotive parts, pipe, film, geomembranes, toys, and filament.
Ethylene Polymers, Chlorosulfonated
Authors: Ennis Royce 
Published: October 2003

AbstractChlorosulfonated polyethylene, introduced in 1951, represents a family of chlorinated polymers based on various types of polyolefins and some prefunctionalized resins. They are usually prepared by simultaneous chlorination and chlorosulfonation in a homogeneous solution with an inert solvent. Introduction of chlorine atoms onto the polyolefin chain interrupts its regularity, converting the crystalline polymer into semiplastic, elastomeric, or rigid plastic consistency, depending on the level and distribution of chlorine atoms. The sulfonyl chloride group provides a site for a variety of cross‐linking reactions for thermoset applications. Raw polymer processing and vulcanizate mechanical properties depend on the base resin parameters of molecular weight, molecular weight distribution, and density, in addition to the chlorine and cross‐link type. When properly compounded and cross‐linked, these polymers give superior resistance to oil, heat, and ozone compared to most other elastomers, making them valuable in many automotive, construction, and coating applications. Specific adhesion characteristics of the sulfonyl chloride group and other functionality, eg, maleic anhydride graft, leads to special applications as primers and binders.
Ethylene Acrylic Elastomers
Authors: Wu Yun‐Tai , Stewart Mark A. 
Published: October 2003

Abstract
Ethylene acrylic elastomers have been successfully used in automotive underhood applications where heat and oil resistance are required. Additionally, ethylene acrylic elastomers offer excellent compressive stress relaxation, dynamic fatigue resistance, vibration dampening, and resistance to acid condensates, making it suitable for demanding applications including seals, gaskets, hoses, and torsional dampers. New products with improved properties are introduced to further enhance the performance range to meet future needs for improved fuel efficiency and higher exhaust gas emission standards.
Antifoaming Agents
Authors: Owen Michael J. 
Published: October 2003

AbstractA review is presented of the materials used to control or eliminate foam in industrial processes and how they function. These materials are classified by their chemical type. Main active liquid‐phase components are hydrocarbon oils, polyethers, and silicone fluids; main solid‐phase components are waxy hydrocarbons and hydrophobic silica. Ancillary agents such as surfactants and carriers are also incorporated in some defoamer formulations. Sources of significant commercial defoamer products are listed. The theory of foaming and defoaming is outlined with emphasis on surface behavior such as entering, spreading, and dewetting phenomena. The role of dispersed hydrophobic solids is highlighted. Applications in various areas are briefly reviewed, including adhesives and sealants, chemical processing, cleaning compounds, construction, fermentation processes, fertilizers, food and beverages, leather, metal working, oil and petrochemicals, coatings, polymers, pulp and paper, textiles, and wastewater treatment. Economic and health and safety factors are considered. Test methods, such as pneumatic, dynamic, shaking, pour, stirring, and blending methods are also briefly reviewed.
Phosgene
Authors: Dunlap Kenneth L. 
Published: October 2003

AbstractPhosgene is a colorless liquid with a low boiling point. It is manufactured by the reaction of carbon monoxide and chlorine over activated carbon. It is a very toxic substance, and extensive safety procedures and equipment have been developed to help ensure its safe handling. Phosgene is an important and widely used intermediate for chemical synthesis. Its primary use is for the manufacture of polyisocyanates for the polyurethane industry. Phosgene is also used in the production of polycarbonate, chloroformates, agrochemicals, and intermediates for pharmaceuticals and dyestuffs.
Surface Properties
Authors: Koberstein Jeffrey T. 
Published: October 2003

AbstractThe properties of a polymer surface control many important industrial technologies because of their effects on such generic phenomena as wetting or spreading, adhesion, and release. The most important surface property for most applications is the surface tension, that is, the energy required to create an air–polymer interface or surface. This article reviews how the surface tension and other properties of an air–polymer interface depend on intrinsic factors such as the nature of the polymer, its end groups, and its molecular weight, as well as external factors such as temperature. Empirical methods for estimating surface tension and first principle methods for calculating surface tension are presented. Classical themodynamics pertaining to surface properties are presented to illustrate how surface tension is related to the work of adhesion and to the wetting of a polymer on a substrate. Surface properties are also described for heterogeneous polymers such as random, graft, and block copolymers; end‐functional homopolymers; and polymer blends. Theoretical frameworks and experimental data are presented to describe the following: the preferential surface segregation of the lowest energy component in these heterogeneous systems, how these segregation effects depend on molecular properties of the constituents, and how these systems reorganize when exposed to different environments. The most useful methods available for the measurement of polymer surface tension are discussed to conclude the article.
Perfluorinated Polymers, Tetrafluoroethylene–Perfluorovinyl Ether Copolymers
Authors: Gangal Subhash V. 
Published: October 2003

Abstract
Perfluoroalkoxy (PFA) fluorocarbon resins are designed to meet industry needs in chemical, electrical, and mechanical applications. These melt‐processible copolymers contain a fluorocarbon backbone in the main chain and randomly distributed perfluorinated ether side chains. A combination of excellent chemical and mechanical properties at evevated temperatures results in reliable, high performance service to the chemical processing and related industries. Chemical inertness, heat resistance, toughness and flexibility, stress‐crack resistance, excellent flex life, antistick characteristics, little moisture absorption, nonflammability, and exceptional dielectric properties are among the characteristics of these resins. These resins are produced by copolymerizing tetrafluoroethylene and perfluorovinyl ether in aqueous or nonaqueous media. The polymer is separated and converted into various forms, such as extruded cubes, powders, beads, or dispersions. PFA resins are fabricated by the conventional melt‐processing techniques used for thermoplastics. A general‐purpose grade is designed for a variety of molding and extrusion applications such as tubing, shapes, molded parts, and insulation for electrical wire and cables. Valves and fitting liners are made by a transfer‐molding process. Some grades of this polymer are suitable in semiconductor manufacturing, fluid handling systems for industry or life sciences, and instrumentation for precise measurements of fluid systems.