bluuebunny/crossref_metadata_2025_split huggingface dataset:
Elasticity, Rubber‐like
Authors: Queslel J. P. , Mark J. E. 
Published: October 2003

AbstractLong, flexible polymer chains with high mobility and weak interchain interactions may be covalently linked together to form network structures. These materials exhibit a unique behavior called rubber‐like elasticity, which is high and reversible deformability (up to 10 times the original dimension). The origin of elasticity at thermodynamic equilibrium is the decrease in entropy of the chains between cross‐linking points resulting from the extension. Elastomers therefore follow thermodynamic laws similar to those for gases. There is a minor intramolecular energetic component in the retractive force which can be extracted from thermoelasticity experiments and is related to conformational energy changes of the chains.Most of the theoretical and experimental works in the field of rubber‐like elasticity have been devoted to the characterization of network structures. Molecular models based on statistical mechanics have been applied to the analysis of equilibrium properties such as stress–strain measurements in uniaxial extension and swelling by a solvent. The real behavior of rubbers is between the predictions of the simple affine and phantom models and is well represented by molecular models which include entanglement constraints. These models associated with topological descriptions of networks are powerful tools to describe network structures.
Thermoplastic Elastomers
Authors: Holden Geoffrey 
Published: October 2003

AbstractThermoplastic elastomers are a rapidly growing part of the polymer industry. They combine the physical properties of rubbers with the ability to be processed on equipment designed for thermoplastics. This gives them two advantages over conventional rubbers—processing is much faster and scrap is recyclable. In addition, thermoplastic elastomers can be used to formulate adhesives, compatibilize and modify other thermoplastics, and modify asphalts. There are several types of thermoplastic elastomers. The most important are styrenic block copolymers, multiblock copolymers, and hard polymer/elastomer combinations. Most thermoplastic elastomers are multiphase systems, with one or more hard phases and an elastomeric phase. The properties of individual thermoplastic elastomers depend on the properties and proportions of the individual phases and on their morphology. This article reviews and compares the structure, synthesis, and properties of thermoplastic elastomers of all types. It includes details of their commercial uses, trade names, and consumption.
Electrically Active Polymers
Authors: Zarras Peter , Irvin Jennifer 
Published: October 2003

AbstractIn the years since the discovery of conductivity in polyacetylene, a tremendous amount of research has been devoted to the synthesis, characterization, and application development of electrically active polymers. This article reviews the theory of conduction in these materials and discusses the syntheses of the major types of electrically active polymers. Electrical conductivities of these polymers are presented along with stability and mechanical and optical properties. The unique combinations of properties in these materials have led to a wide range of practical applications, which are also discussed.
Electrooptical Applications
Authors: Dalton Larry R. 
Published: October 2003

AbstractAn overview of organic electronic electrooptic materials and the applications of those materials in prototype devices is given. This overview is set in the context of competing technologies. Quantum and statistical mechanical theoretical methods have recently provided significantly improved guidance in understanding organic electrooptic material structure/function relationships, leading to the systematic increase in electrooptic activity of such materials to values 15 times larger than the current commercial standard lithium niobate. In addition to discussion of electro‐optic activity, auxiliary properties of bandwidth, optical loss, thermal stability, photochemical stability, mechanical properties, and processability are discussed. Since the year 2000, substantial advances have been achieved in the processing of organic electrooptic materials and the integration with disparate materials, e.g., silicon photonics. For example, cycloaddition reactions have been employed to dramatically improve the thermal and photochemical stability of organic electrooptic materials. Integration of organic electrooptic materials with silicon photonic device structures have lead to new performance records, device concepts, and paves the way for the chipscale intergration of electronics and photonics. The fabrication of conformal and flexible devices have also been demonstrated with organic electrooptic materials and such materials have been amenable to production of complex photonic circuitry by nanoimprint/soft lithography techniques.
Ethylene Polymers,LDPE
Authors: Maraschin Norma 
Published: October 2003

AbstractLow density polyethylene (LDPE) was the first thermoplastic polyolefin used commercially. It was discovered serendipitously in 1933 and was quickly utilized for radar sheathing during the war. LDPE, along with high density polyethylene (HDPE) and linear low density polyethylene (LLDPE), offers an unparalleled combination of low cost, ease of fabrication into a variety of end uses, and balance of physical properties. Polyethylene has displaced paper, metal, wood, and other materials of construction. LDPE is unique in its polymerization process. Free‐radical‐initiated polymerization is used to make LDPE, as compared to transition‐metal catalysis for HDPE and LLDPE. The free‐radical process leads to the unique molecular structure of LDPE: the presence of long‐chain branching. The long‐chain branching imparts unusual rheological behavior in both shear and extension. LDPE is used in a variety of applications, such as film, coating, molding, and wire and cable insulation. One of the reasons for its wide range of utility is its thermal stability and low toxicity.
Ethylene Polymers,LLDPE
Authors: Simpson D. M. , Vaughan G. A. 
Published: October 2003

AbstractZiegler–Natta‐catalyzed linear low density polyethylene (LLDPE) was first commercialized in the late 1970s. Unlike low density polyethylene (LDPE) produced in the high pressure process, Ziegler–Natta LLDPE has no long‐chain branching and has a narrower molecular weight distribution. LLDPE offers improved mechanical properties relative to LDPE. Metallocene‐catalyzed LLDPE(mLLDPE) resins, commercialized in the 1990s, are more compositionally homogeneous than LLDPE and have narrower molecular weight distributions. mLLDPE resins offer improved toughness properties relative to LLDPE. LLDPE resins are used in film, injection molding, blow molding, rotational molding, tubing, and wire and cable coating applications.
Extrusion
Authors: Rauwendaal Chris 
Published: October 2003

Abstract
Extruders are the most common machines in the plastics processing industry. Extruders are used not only in extrusion operations, but also in molding operations for example, injection molding and blow molding. Essentially every plastic part has gone through an extruder at one point or another; in many cases, more than once. In typical plastics extrusion processing a viscous melt under pressure is forced through a shaping die in a continuous stream. The feed stock may enter the extrusion device in the molten state, but more commonly it consists of solid particles that must be subjected in the extruder to melting, mixing, and pressurization. This article discusses extruders and the extrusion process in detail, including screw design, dies, mixing, melting, conveying, and degassing.
Fatigue Behavior of Polymers
Authors: Lesser Alan J. 
Published: October 2003

AbstractPolymers and polymer‐based composites are increasingly displacing more traditional materials in a wide variety of engineering applications, and as such characterization of their fatigue behavior is of utmost importance. This article presents a general overview of the fatigue behavior of polymers. After a brief introduction that includes general terminology, the effects of test conditions (sample geometry, loading frequency, etc) are discussed. The effects of these conditions are also discussed in relevance to both the high cycle and low cycle fatigue behavior. Current models for predicting fatigue life are also reviewed, including cumulative damage theories and fatigue crack propagation models. Morphological and environmental effects are then discussed over a broad range of semicrystalline, amorphous, and modified polymer systems.
Fibers, Elastomeric
Authors: Boliek John E. , Denney Stacy A. 
Published: October 2003

Abstract
Elastomeric fibers are used commercially with hard fibers to provide stretch properties in textiles. The elastomeric polymer can be spun or cut into fibers that provide high elongation, low modulus, and good recovery from stretching. This article contains a description of the chemical composition, mechanical properties, and manufacturing methods of both natural and synthetic elastomeric materials. The economic aspects and commercial uses of the fibers in the textile industry are also described.
Films, Manufacture
Authors: Mount Eldridge M. 
Published: October 2003

AbstractThis article describes the methods and materials used in the commercial manufacture of polymer film products. Techniques for cast and oriented films using a variety of film‐making equipment are discussed and explained. The manufacturing process is broken down into a series of critical process steps to describe the function of each in the film‐making process and the impact of each on the film properties produced. Both extrusion and solvent‐based casting methods are described and a description of film‐finishing processes is given.
Fluorocarbon Elastomers
Authors: Worm Allan T. , Grootaert Werner 
Published: October 2003

AbstractFluorocarbon elastomers are fluorine‐containing cross‐linked amorphous polymers with a carbon–carbon backbone, which are designed for demanding service application in hostile environments. This article reviews the development history of fluorocarbon elastomers and the basic properties of the polymers. A brief manufacturing process for the polymers is presented along with processing information to convert the fluorocarbon elastomers into useful parts for various applications. Major uses and specifications for these uses are also presented.
Fracture
Authors: Kausch Hans‐Henning , Williams J. G. 
Published: October 2003

AbstractFracture of polymers is defined, and the essential phenomena of stable and unstable crack propagation are described and quantified using different concepts of fracture mechanics (linear elastic, confined plasticity, essential work of fracture). Particular attention has been given to a discussion of toughness and time‐dependent strength in terms of molecular parameters (eg, chain architecture, degree of entanglement, and molecular mobility) and of extrinsic variables (state of stress, rate of loading).
Glass Transition
Authors: Bicerano Jozef 
Published: October 2003

AbstractThe glass transition is by far the most important one among the many transitions and relaxations observed in amorphous polymers. It has a drastic effect on the properties and processing characteristics of such polymers. It is important in semicrystalline polymers as well, but its role diminishes in importance with increasing crystalline fraction. The glass‐transition temperature (Tg) can be defined operationally asthe temperature at which the forces holding the distinct components of an amorphous solid together are overcome, so that these components are able to undergo large‐scale molecular motions, limited mainly by the inherent resistance of each component to such flow. The practical effects of the glass transition on the processing and performance characteristics of polymers, as well as the key aspects of its physics, are implicit in this definition.
Hardness
Authors: Calleja F. J. Baltá , Flores A. 
Published: October 2003

Abstract
Hardness is related to the resistance to local deformation of a material surface when indented, drilled, sawed, or abraded. Hardness is shown to be a mechanical property that provides a rapid evaluation of variations in polymer microstructure and morphology. Recent results concerning the microhardness of semicrystalline polymers and amorphous polymers relating to their structure are reviewed. The hardness of polymer glasses is first discussed in relation to their glass‐transition temperature. The development of structure during crystallization of glassy polymers as revealed by microhardness is brought up, and the hardness dependence on structural parameters such as the degree of crystallinity and the crystalline lamellar thickness is discussed. The close existing relationship between crystal hardness and melting temperature is presented. The correlation between microhardness of polymers and macroscopic mechanical properties (yield stress and Young's modulus) is highlighted. Some applications of the microhardness technique to polymer blends are also illustrated. In case of uniaxially oriented polymers, the indentation anisotropy is shown to provide information of the elastic response of the material along chain direction. Finally, the present review presents a comprehensive summary of the different methods used for the determination of hardness numbers, stressing the correlation between the hardness values resulting from different indenter geometries.
Heat Stabilizers
Authors: Mesch Keith A. 
Published: October 2003

AbstractHalogenated polymers, particularly poly(vinyl chloride) (PVC) and poly(vinylidene chloride) (PVDE), require the use of heat stabilizers for effective processing. A variety of chemical classes are effective commercial heat stabilizers since they prevent the catastrophic degradation of these polymers at normal processing temperatures. The most effective class of heat stabilizers are the organotin mercaptides which can provide effective stabilization at dosages of the order of 1% or less of the PVC. Mixed metal products, consisting of combinations of calcium and zinc or barium, calcium and zinc soaps are used extensively in many flexible PVC applications. Heat stabilizers based on lead soaps and salts have been used commercially in PVC since the 1930s. Within the past few years. completely new heat stabilizer technologies, based on new organic compounds, have been introduced to the market for rigid PVC processing.All heat stabilizers must provide several functions to stabilize PVC. They must neutralize hydrogen chloride, react with “defect sites” on the polymer to replace weakened carbon–chlorine bonds, prevent autoxidation effects, and disrupt conjugated polyenes on polymer. Reactive mechanisms for the major classes of technologies are reviewed. The heat stabilizers must be very cost‐effective in a highly competitive marketplace. Several suppliers and their major products are highlighted. Health and safety concerns for the major classes of heat stabilizers are also presented.
Hydrogels
Authors: Künzler Jay Friedrich 
Published: October 2003

AbstractThe area of hydrogel research has expanded dramatically in the last 10 years. This is due primarily to the fact that hydrogels have performed well for biomedical applications. This has been true for both the synthetic‐ and natural‐based hydrogels. This article focuses on the properties, classes, preparation, and application of hydrogels, with particular emphasis on the design of hydrogels for biomedical applications including ophthalmic, drug delivery, tissue engineering, and biosensors. Advances in the use of hydrogels to restore, augment, or replace the natural functions of the tissues and organs of the body are described.
Hyperbranched Polymers
Authors: Hult Anders 
Published: October 2003

Abstract

Hyperbranched polymers are polymers based on A

x

B‐monomers, ie, monomers having one B‐functionality and two or more A‐groups resulting in polymers with a potential branching point in each repeat unit. The properties of hyperbranched polymers have been shown to depend on several parameters, the most important ones ate the backbone and the end‐group structure in combination. The properties of hyperbranched polymers differ from linear polymers, for example, the solubility, which is much higher for hyperbranched polymers. Attachment of reactive end‐groups in various amounts leads to thermoset structures where the
T
g
and cross‐link density can be greatly varied for the same hyperbranched polymer.

A wide variety of hyperbranched polymers has been described in the literature. The synthesis of hyperbranched polymers can be done in several different ways. Classical condensation reactions are the most commonly used. The condensation reactions are either made in bulk or in solution where the A

x

B‐monomers are condensed by themselves or in combination with a B

y

‐core monomer. Another approach to the synthesis of hyperbranched polymers is the use of self‐condensing vinyl polymerization which is a way of using vinyl‐functional monomers to obtain hyperbranched polymers.
Impact Resistance
Authors: Yee Albert F. , Sue Hung‐Jue 
Published: October 2003

Abstract
The impact resistance of plastics is one of the most important tests for the practical use of these materials in various applications. The commonly used standard test methods and the testing equipment are described in some detail in this article. The test results are related to basic mechanical properties, where possible. In particular, a method for correlating notched impact results with a more rigorous test of energy release rate is described. A few examples of techniques for toughening plastics for greater impact or fracture resistance are given, along with the toughening mechanisms.
Injection Molding
Authors: Bozzelli John W. 
Published: October 2003

AbstractInjection molding is an important thermal forming process for converting plastics, metals, ceramics, and wax into complex three‐dimensional products. Products range from large automotive body sections to microscopic gears and connectors. Applications appear limitless. Variations and extensions continue to evolve as this technology helps change the quality of life for the world's population. Injection molding consumed approximately 32 wt% of all plastics sold worldwide in the year 2000, roughly 4.95 × 107metric tons. This is an industry that will continue to grow and drive national economics.
Ionomers
Authors: Kim Joon‐Seop 
Published: October 2003

AbstractIonomers are polymers with low dielectric constants, containing a relatively small number of ionic groups, and they usually show unique physical properties, for example, two glass‐transition temperatures, small‐angle x‐ray scattering peaks, unusual transport properties, and high melt viscosity. Since the 1950s, the ionic interaction has been known as a very important factor in modifying polymer properties, and thus has received considerable attention from industrial as well as academic arenas. This overview begins with a brief discussion on three models of ionomers, ie, core–shell model, hard‐sphere model, and Eisenberg–Hird–Moore model, and then moves on to glass transitions. Styrene‐based ionomers, presently the best‐understood family of ionomers in terms of structure–morphology–property relationships, are described. There is a discussion of crystalline ionomers, block ionomers, and end‐capped ionomer systems. Three different types of plasticization using polar, nonpolar, and amphiphilic plasticizers are discussed. Some major applications of ionomers are selectively demonstrated very briefly.
Isocyanate‐Derived Polymers
Authors: Ulrich Henri 
Published: October 2003

AbstractHomo‐ and copolymers derived from mono‐ and diisocyanates are treated in this article. Also, addition, condensation, and addition/condensation polymers derived from diisocyanates are included. Of commercial interest are segmented block copolyamide elastomers produced from methylene di‐p‐phenylene isocyanate (MDI) and macrodicarboxylic acids and dicarboxylic acids. This reaction polymerization is conducted in a vented extruder or in solution. Also, engineering plastics are obtained from diisocyanates and dicarboxylic acids. Poly(amide imides) and poly(imides) are produced from MDI and TDI (toluene diisocyanate) and trimellitic acid anhydride and isophthalic acid and dianhydrides, respectively. Heterocyclic polymers with useful high temperature properties made from MDI and suitable monomers by a polyaddition/condensation reaction are also included.
Lignin
Authors: Lebo Stuart E. , Gargulak Jerry D. , McNally Timothy J. 
Published: October 2003

AbstractThe word lignin is derived from the latin wordlignummeaning wood. It is one of the main components of all vascular plants and the second most abundant polymer in nature. This article describes the current understanding of the structure of this complex natural polymer. The number and types of different chemical bonds present in lignin are discussed as are the ways in which different lignins are identified and their distributions determined in plant tissues. Means for isolating lignin from wood are described, and the chemical and physical properties of the resulting lignins are reviewed. The various chemical and instrumental methods for characterizing isolated lignins are also discussed. The article concludes with a review of commercial lignin products, including a discussion of producers, production methods, modification reactions, and the many industries in which lignins are used.
Mass Spectrometry
Authors: Guttman Charles M. 
Published: October 2003

AbstractThe two most common methods used to place charged high mass molecules into the gas phase, electrospray ionization and matrix‐assisted laser desorption/ionization (maldi), are described. Because of its dominant use with synthetic polymers, the maldi method is described in detail, including sample preparation and data analysis and the problems this method poses. The time‐of‐flight mass spectrometry system is also described in detail since it is the most common in use today for synthetic polymers. A variety of applications of maldi to synthetic polymers is reviewed. This includes molecular mass distribution, molecular composition distribution of copolymers, polymer architecture, combinations of maldi‐tof‐ms with size exclusion chromatography and other forms of polymer chromatography, and the use of maldi in elucidating polymer chemical reaction mechanisms.