bluuebunny/crossref_metadata_2025 huggingface dataset:
Economic Impact Analysis of Genetically Modified Crops
Authors: Naseem Anwar , Pray Carl
Published: July 2004

This chapter documents, evaluates and synthesises the actual impact of GM crops to date by reviewing previous surveys and empirical studies. We also review the ex‐ante studies and studies based on experimental trials. For the most part we limit our analysis to the impact at the farm level, as this is where the bulk of the evidence lies and where impacts are most direct and measurable. Given that widespread adoption of GM crops will have implications for the whole economy, we also review studies that estimate impacts at the national and global level, with an emphasis on who captures the benefits from the adoption of GM crops. Furthermore, since most of the current set of GM crops affects input use, we review the data on how adoption has affected pesticide/herbicide use.
Intellectual Property Rights and Patent Regimes in Biotechnology and their Impact on Agriculture Development in the Developing World
Authors: Henson‐Apollonio Victoria
Published: July 2004

Modern biotechnology has produced a revolution in agriculture, both in the developing and industrial world. Along with the scientific innovation, a transformation has occurred in the ways that information and knowledge is being transferred, as well. Intellectual property protection schemes have had a variable influence on both the rights associated with actual and perceived control of, and, use of, innovations in agricultural development. This perception has been particularly volatile in the developing world. This chapter discusses technical aspects of intellectual property and then reviews the role of IP regimes in the diffusion of transgenic/genetically engineered plant biotechnology (transgenic cotton) in two selected emergent countries, India and Argentina.
Safe or Unsafe? 15 Years of EU Risk Assessment Research on GMOs
Authors: Economidis Ioannis , Kessler Charles
Published: July 2004

The European Union has been active in supporting research on the safety of GMOs for over 15 years through the funding mechanism of the European Commission. This chapter examines what has been achieved. Although no particular safety or environmental problems have been revealed areas of concern remain. Communication of safety research results appears to be a particular bottleneck, especially from the perspective of public perception.
Factors Influencing Public Policy Development in Agricultural Biotechnology
Authors: Ammann Klaus , Ammann Biljana Papazova
Published: July 2004

It is obvious, that agricultural biotechnology is one of the centreer points of the recent debate. If we focus on the most neuralgic point, it is genetic engineering as a tool for modern plant breeding. It is clear that lay people are anxious regarding the new developments, and it is not only ignorance which makes them fearful. There is a big divide between lay people and scientists and between politicians and citizens, to name just two major divides. The important question is, how can we overcome divides of this dimension and what do we want to set as new policy goals in the appropriate time scales?
Political and Social Risk Amplification of GMOs
Authors: Jamison Wesley , BenDor Todd , Kolpak Adrianne , McDonnell Maureen
Published: July 2004

Risk is not a simple phenomenon; contrary to the arguments of frustrated scientists who claim evidentiary support for the development and release of genetically modified organisms (GMOs), opponents of these organisms claim that the risks associated with their release are unacceptable. Obviously, the evaluation of risk is often contentious and ambiguous, and yet the phenomenon of how people actually evaluate risk is not widely known among scientists. Hence, we present a review of the literature on risk that underscores its complexity. Scholars argue the merits of different types of risk assessment, but most agree that the process is far more complex than simple cost/benefit analyses. Indeed, the literature presents a plethora of theories, ranging from economic and actuarial assessment to psychological and social assessments. We agree with the social constructionist view, and argue that opponents of GMOs have amplified the socially derived feelings of risk that the various stakeholders and publics harbour towards GMOs. We likewise conclude that GMO opponents are amplifying the factors of control and unknown risk.
Global Social Acceptance of Plant Biotechnology
Authors: Jefferson Hoban Thomas
Published: July 2004

Plant scientists made remarkable strides during the 20th century. Now, biotechnology has the potential to significantly increase the quality and quantity of food and other needed products. This is particularly important given the increased demand for meat and poultry throughout much of Asia. Developing countries will benefit most from these new crop varieties designed to have enhanced nutrition, while minimising the impacts on the environment. However, the potential benefits of biotechnology will only be realised if society accepts the science and new products as safe, effective and ethical. As we have learned from the ‘GMO’ controversy in Europe, such acceptance is not guaranteed.
The Story of Bollgard® Cotton
Authors: Purcell John P. , Oppenhuizen Mark , Wofford Thomas , Reed Andrew J. , Perlak Frederick J.
Published: July 2004

Bollgard® cotton is one of the great success stories for agricultural biotechnology. It broke new ground as a commercially successful transgenic plant product that could protect itself from damage from insect pests. This provided farmers with a dramatic new technology that offered significant benefits over the chemical insecticides that were being used. Delivering this product took many years of discovery and development and required significant scientific advances. Since its introduction in 1996, the use of Bollgard® cotton has expanded rapidly. It is now a valuable tool for agriculture with commercial growings in nine countries on five continents. Bollgard® cotton provides economic, environmental and social benefits for large and smallholder farmers around the globe.
Benefits of Commercialised Biotechnology‐Derived Crops in the United States
Authors: Sankula Sujatha , Gianessi Leonard
Published: July 2004

This chapter examines the importance of pest management in crop production and details the commercially available biotechnology‐derived traits and the need for them in the context of available pest management options in conventional crops. The discussion is mainly focused on the actual and potential benefits of this innovation for crops commercialised so far in the United States. Economic advantage to growers is the ultimate key factor, which determines the adoption and success of biotechnology‐derived crops. Economic benefits normally result from reduced input costs, or increased yields or both.
Agricultural Biotechnology for Developing Countries: A Strategic Overview
Authors: Sasson Albert , Elliott Malcolm C.
Published: July 2004

More than 2 billion people have no food security while 840 million of them are chronically malnourished. Six million children under the age of five die each year as a result of hunger and malnutrition. This crisis of food security is focused in the developing countries where the populations continue to increase at an alarming rate. In order to confront the problem, which is often exacerbated by a decrease in the area of land available for agriculture coupled with a decrease in the amount of water available for irrigation and an increase in the environmental impact of agrochemicals, it will be necessary to fully exploit agricultural biotechnology.
Agricultural Biotechnology in Latin America and the Caribbean
Authors: Cockcroft Claire E. , Herrera-Estrella Luis , Borroto Nordelo Carlos G.
Published: July 2004

The area of land viable for agriculture is diminishing each year due to topsoil erosion, loss of soil fertility, water insecurity and climatic change, factors which limit productivity and threaten crop yields. The changing climate will exaggerate the existing differences between developed and developing countries and may also see pests and diseases infiltrating wider geographical zones, further threatening productivity. These factors are particularly important for many countries in Latin America and the Caribbean (LAC). Hence, with the current range of agricultural land having reached a supply threshold and limited prospects of increasing the area, the rate of increase in food production will not keep pace with the rate of population growth.

Modern biotechnology offers a means of delivering sustainable agricultural practices and this chapter provides an overview of the institutions and research projects in LAC countries, whose objective is to provide more food in a safe, sustainable way. There is a wealth of research being undertaken in Latin America on both commodity crops and locally‐important staples. Molecular breeding, genetic engineering,
in vitro
micropropagation, germplasm screening and conservation projects are being used to identify useful traits, improve resistance to a variety of abiotic and biotic factors and boost crop yields throughout the region. An overview of the current status of GM crops–research, approval and commercialisation status–demonstrates that these biotechnological methods, together with the development of novel bioproducts and integrated pest management strategies, are facilitating an environmentally conscious attitude to crop protection and enabling more sustainable agricultural practices in a number of countries from the LAC region.

Engineering crops that are tailored to the environment, so as to resist climate change and environmental stress, may permit marginal lands to be brought into agricultural use to produce locally‐important crops and commercially relevant crops for a growing population, as well as feed for the livestock on which the population depends. Some countries in Latin America, such as Costa Rica and Colombia, have a particularly rich biodiversity so changing agricultural practices and the adoption of genetically modified (GM) varieties in such regions must not pose a threat to local biodiversity. Projects to assess the likelihood of GM traits passing into weedy and wild relatives are being conducted in centres of biodiversity for key crops within Latin America.

Agriculture in Latin America will come under increasing pressure to provide food, income and livelihoods for current and future generations. Its success will depend on the appropriate integration of traditional methods with contemporary technologies to enhance productivity in a sustainable way, without jeopardising ecological security.
Poverty Alleviation, Plant Biotechnology and the Importance of the CGIAR International Agricultural Research Centres
Authors: Spillane Charles , Doyle Aisling
Published: July 2004

Over 75% of the 1.2 billion who live in extreme poverty currently live in rural areas, and over half of the poor will still be located in rural areas by the year 2025. Food staples can absorb half the consumption of the poor who live on less than US $1 per day. At present the rural poor who subsist on less than a dollar a day are not a target market for any research and development efforts funded by venture capital. Agricultural biotechnology can contribute to poverty alleviation if public sector research funding and activities are targeted towards the needs of the poor. Such pro‐poor agricultural biotechnology will be most effective if it is integrated with existing poverty reduction approaches and measures. Most agricultural biotechnology research and development is conducted in institutions that have minimal multi‐disciplinary capacity or expertise to accurately assess the livelihood needs of the rural poor. Many public sector agricultural research institutions such as NARs, universities and the Consultative Group on International Agricultural Research (CGIAR) play a vital role in conducting applied agricultural research to meet the needs of the poorer groups of society, who do not represent a lucrative commercial market for most companies. In particular, the CGIAR is an example of an institution, which is explicitly mandated to perform ‘public good’ oriented agricultural research to meet the needs of the poor. Yet, public funding for pro‐poor agricultural research (including biotechnology) is declining, even though alleviating rural poverty is central to meeting the primary Millennium Goal of the world's governments who stresses the broad global commitment to halve the proportion of people living in extreme income poverty (less that 1$ a day) by the year 2015. Sustainable funding strategies for pro‐poor agricultural biotechnology research will require a clearer definition of pro‐poor research targets and objectives. In this regard, there are lessons to be learnt from the innovative funding strategies developed recently by the pro‐poor biomedical research community. There remains a pressing need to actively develop policies, mechanisms and/or institutions that ensure that the poor could benefit from agricultural biotechnologies.
Crop Biotechnology for Developing Countries: Opportunity and Duty
Authors: Khush Gurdev S. , Ma Julian
Published: July 2004

Plant biotechnology has the enormous potential to benefit mankind through numerous applications. Perhaps the most significant beneficiary will be the poor in the developing countries, where illnesses associated with malnutrition and infectious diseases are most prevalent. There are several key areas where a pressing need exists to develop new technologies. These include increasing the productivity of agriculture and tackling the problems of malnutrition including those of micronutrient deficiencies. Plant biotechnology can also be harnessed to improve health care and disease control in other ways, including the production of recombinant pharmaceuticals such as medicines, antibodies and vaccines. In order to achieve these goals, there are not only technical hurdles that need to be overcome. The greatest challenges will be to assuage public concerns and develop momentum within the established pharmaceutical industry.
Drilling Fluids
Authors: Ukeles Shmuel D. , Grinbaum Baruch
Published: July 2004

Drilling fluids (muds) play a vital role in the drilling of oil and gas wells. These muds are typically complex chemical mixtures formulated to perform a variety of functions under a wide range of down hole temperatures and pressures, but yet are nondamaging to the environment and safe for personnel to handle. These fluids are circulated down the hollow drill string and up the annulus, formed by the drill string and the hole to remove formation material dislodged by the bit. The fluids must have sufficient density to offset formation pressures to prevent a blowout and to maintain a stable well bore, but be formulated to prevent excessive loss of fluid to permeable formations. Other important functions include lubrication of the drill bit and drill string, collection of information about subsurface formations, and noncorrosivity to surface and down hole equipment. Drilling fluids are composed of liquids (water, petroleum oils, and other organic liquids, eg, synthetic brine fluids), dissolved inorganic and organic additives, and suspended, finely divided solids of various types. This article describes drilling fluid classification, properties, materials used as drilling fluid additives, testing, economics, and an update on current environmental restrictions on drilling fluids/muds in the North Sea and in the Gulf of Mexico. A detailed section has been devoted to clear brine drilling fluids (CBFs) that are used in completion and workover operations. Also presented is a selection of new and recent drilling fluid formulations from the patent literature.
Dyes, Application and Evaluation
Authors: Glover Brian
Published: July 2004

The physical and organic chemistry of dyes and the dyeing process is described outlining the importance of the fiber choice, the basic chemistry of the dye, the interactions between dyes and fibers, and the driving forces of the dyeing process. The molecular design of dyestuff molecules to give desired dyeing properties and performance is outlined, as are the basic principles of the physical chemical processes taking place in the dyebath. Detailed practical dyeing procedures including preparation, dyeing mechanisms, dyestuff selection, and practical processes are given for the primary fiber types: cellulose (direct, reactive, vat, and other dyes); wool (acid, mordant, metallized, and reactive dyes); synthetic polyamides (acid, metallized, disperse, and other dyes together with the use of auxiliary agents to enhance dyeing behavior); polyacrylonitrile (cationic dyes); and polyester and related synthetics such as acetates (disperse dyes). The equipment used in bulk dyeing is also described. Textile printing techniques and paper and leather coloration are included. The main methods used for assessing the fastness of dyed fabrics to agencies they are likely to be exposed to in use, eg, light or water, are outlined, together with the methods of classifying and characterizing dyestuffs and their performance.
Dyeing
Authors: Bide Martin
Published: July 2004

Dyes are used to color textile fibers, paper, and leather. Today's dyes are almost exclusively synthetic: They are classified chemically and by application class. The properties of the dyes and of the substrates to which they are applied (and their interactions with water as an application medium) lead to the attractive forces that drive the dyeing process, and to an understanding of the thermodynamics and kinetics of dyeing.

Practical dyers control their processes with agitation, heat, and auxiliaries, and aim to achieve a dyeing that is the correct color, level, fast to subsequent use, in an efficient and profitable manner.

The wide range of textile fibers requires different dyes and application processes and conditions. Dyes can be applied in batch or continuous processes, and dyeing machines are also designed to handle material at different stages of the textile chain (fiber, yarn, fabric, and garment). The application of dyes to paper and leather takes into account the ways in which those materials are processed.

Dyeing should lead to a level coloration, but dyes are also printed on textiles to provide colored patterns. Printing is carried out with dyes and with pigments, in a range of styles and with a variety of printing machines.

The fastness of colored materials to many different agencies can be assessed using standard test methods. Dyes themselves can be tested for application performance, and can be analyzed both qualitatively and quantitatively.
Electroless Plating
Authors: Krulik Gerald A.
Published: July 2004

Electroless plating is the controlled autocatalytic deposition of a continuous metallic film on a nonconductive or a metallic article. High purity chemicals are needed for the electroless coatings that are applied for both functional and decorative uses. Key application areas are multilayer and surface mount printed circuit boards, radio frequency interference shielding for computers, corrosion‐ and wear‐resistant metal surfaces, and lightweight plated plastics. The ability to produce metal deposits in controlled patterns makes electroless plating of primary importance to modern electronics technology.

The most important electroless plating baths are copper and nickel‐phosphorus. Electroless gold, nickel‐boron, and composites of nickel having particles for higher wear resistance or greater lubricity are also commonly used. Aluminum, steel, copper, and other metals, as well as plastics, ceramics, glass, fibers, and composite materials, are all coated by means of electroless plating.
Flocculating Agents
Authors: Heitner Howard I.
Published: July 2004

Flocculating agents are chemical additives that cause suspended solids to form aggregates called flocs. These agents are used in water treatment, municipal and industrial waste treatment, mineral processing, and papermaking. Flocculating agents are either inorganic salts or water‐soluble organic polymers. They act by shrinking the ionic double layer, or neutralizing the surface charge of suspended particles, or bridging between particles. The type of flocculant used depends on the type of solid‐liquid separation being performed. The physical properties and size of the flocs as well as the rate of floc formation are the critical parameters in this process. Flocculants are usually selected by the results of laboratory‐scale experiments. The manner in which the flocculating agent is mixed with the substrate can affect the results. Special analytical methods are used for some flocculating agents. Some agents or impurities in them may present toxicological or environmental problems. The general economic trend is the replacement of inorganic salts with organic polymers, which give improved performance.
Flocculating Agents
Authors: Heitner Howard I.
Published: July 2004

Flocculating agents are chemical additives that cause suspended solids to form aggregates called flocs. These agents are used in water treatment, municipal and industrial waste treatment, mineral processing, and papermaking. Flocculating agents are either inorganic salts or water‐soluble organic polymers. They act by shrinking the ionic double layer, or neutralizing the surface charge of suspended particles, or bridging between particles. The type of flocculant used depends on the type of solid–liquid separation being performed. The physical properties and size of the flocs as well as the rate of floc formation are the critical parameters in this process. Flocculants are usually selected by the results of laboratory‐scale experiments. The manner in which the flocculating agent is mixed with the substrate can affect the results. Special analytical methods are used for some flocculating agents. Some agents or impurities in them may present toxicological or environmental problems. The general economic trend is the replacement of inorganic salts with organic polymers, which give improved performance.
Polychloroprene
Authors: Glenn Furman E.
Published: July 2004

Polychloroprene has been in commercial use for over 65 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. Latexes are used for various bonding and adhesive applications as well as for dipped goods requiring toughness in the unreinforced film. Monomers can undergo runaway reactions so strict handling procedures must be followed.
Nutraceuticals
Authors: Eggersdorfer Manfred , Burdick David , Goralczyk Regina , Raederstorff Daniel , Riegger Christoph , Schalch Wolfgang , Stöcklin Elisabeth , Weber Peter , Bonrath Werner
Published: July 2004

Nutraceuticals are the active ingredients in functional food or nutritional supplements that deliver a health benefit. The past years have seen an enormous increase in the understanding of the role of these ingredients for health and wellness. Consequently, this resulted in a fast growing market of new active ingredients as well as consumer products containing them. Examples of products well established on the market aren‐β long‐chain fatty acids to reduce cardiovascular riks, probiotics to improve the growth of beneficial intestinal flora, phytosterols to reduce cholesterol uptake and folic acid to reduce homocysteine, a risk factor for cardiovasucular disease. Combinations of essential nutrients and nutraceuticals contribute to wellness, may strenghen the health promoting potential by synergy and could be expected to reduce risk for chromic diseases.

Regulatory authorities worldwide catch up with these developments and provide guidelines and rules and define requirements regarding safety, efficacy, and intake levels.

Based on their deifinition, nutraceuticals contain product classes like vitamins, carotenoids,n‐3 long‐chain fatty acids, polyphenols, flavons and isoflavons, sterols, and an enormous number of products from different chemical structures. Nature provides thousands and thousands of minor constituents from which as a mixture a health benefit has been described or claimed in the literature. The identification of the single compounds and the investigation of their potential health effects are a difficult and science‐intensive process.

This article describes trends in nutrition, processes for the identification of nutraceuticals and major established products as well as products in development including markets and future trends.
Acrylic Fibers
Authors: Capone Gary J. , Masson James C.
Published: July 2004

Acrylic fibers are spun from copolymers in which acrylonitrile is the major component. The fibers are solution spun from solvents such as dimethylformamide, dimethyl sulfoxide, and sodium thiocyanate–water either by wet (extrusion into a nonsolvent) or dry (extrusion into a hot inert gas) technologies. The basic technologies were developed in the 1950s and first commercialized in the United States. Expansion to Europe and Japan soon followed. In the twenty‐first century, the locus has shifted to Asia, with significant downsizing in the United States. An extensive table lists producer capacities. Acrylic fibers occupy market niches such as sweaters, half hose, upholstery, hand‐knitting yarns, and carbon fiber precursor. The technology adapts the basic polymer and fiber for each of these products is described. The physical properties of standard acrylic fiber are compared to those of other synthetic and natural fibers in a table. Stress–strain curves are shown under differing conditions. Chemical properties of the fiber such as resistance to acids and bases and flame retardancy are detailed and compared. Commercial polymer and spinning technologies are explained in detail, including processes for bicomponent and producer‐dyed fiber.
Carbon Fibers
Authors: Newell James A.
Published: July 2004

Carbon fibers provide exceptional properties when used as reinforcing materials in
composite materials
. This article describes the production, processing, and properties of carbon fibers made from a variety of precursor materials. Most commercial carbon fibers are made from polyacrylonitrile (PAN), which must be converted to a thermally stable form that will not melt. The resultant carbon fibers have a fibrillar microtexture and exhibit exceptional tensile strength. Carbon fibers made from stabilized mesophase pitch, either petroleum‐based or synthetic, tend to possess lower strengths, but can exhibit vastly superior lattice‐dependent properties including thermal conductivity and Young's modulus. By controlling the flow of the liquid crystalline mesophase domains, the orientation and properties of the fiber can be improved substantially. High performance polymers such as Kevlar and poly
p
‐phenylene benzobisoxazole (PBO) can be converted directly to carbon fiber without the stabilization step, but have lower mechanical properties. Activated rayon‐based carbon fibers provide an economically attractive means of adsorbing many organic contaminants. Vapor‐grown carbon fibers (VGCFs) are produced by the decomposition of methane or benzene over a catalyst. Submicron VGCFs have commercial applications in batteries, while large VGCFs provide potentially inexpensive filler material in composites.
Characterization of Polymers
Authors: Pethrick Richard A.
Published: July 2004

In order to effectively use polymeric materials, it is important to understand what factors influence their physical and chemical properties. This article attempts to develop a framework for the systematic discussion of the characteristics of polymeric materials in terms of the methods used in their synthesis, the dominant nature of the organization or lack of it in the solids state, and their process ability. Many properties of a polymer are influenced by the length or the polymer chain or its size, and techniques which allow quantification of these properties are very important in defining the nature of a polymer. The final physical properties of a polymer can be influenced by the nature of the structure developed on formation of a solid, and relating physical properties to morphology is often required in order to understand the subtle effects which can be observed and to make polymeric materials commercially interesting for a wide range of applications.
Dynamic Mechanical Analysis
Authors: Menard Kevin P.
Published: July 2004

Dynamic mechanical analysis (DMA) measures the damping of an oscillatory signal in a material. The technique allows the detection of very weak transitions as well as fast determinations of modulus as a function of temperature and frequency, damping, viscosity, and compliance. It is commonly used to study polymer melts as well as solid polymers. It has the advantage of allowing testing on a wide variety of materials, and both liquids and solids can be handled in the same instrument, making it extremely useful for the study of curing systems.
Fractionation
Authors: Soares Joao B. P.
Published: July 2004

Polymer fractionation techniques attempt to fractionate polymers according to specific characteristics of their microstructures as defined by their distributions of molecular weight, chemical composition, comonomer sequence length, tacticity, and long‐chain branching. Because of the heterogeneous nature of polymers, fractionation techniques are essential for understanding structure‐property relationships, polymerization mechanisms and kinetics, and polymer reaction engineering.

In this entry, theoretical models to describe the microstructure of polymers are initially reviewed and used as a basis to understand the several polymer fractionation techniques described in the subsequent sections. Batch fractionation methods are covered next, including temperature variation and solvent/nonsolvent fractionation procedures. The recent technique of crystallization analysis fractionation (Crystaf), together with temperature rising elution fractionation (TREF), are reviewed as methods for fractionation by crystallizability. The well‐established technique for molecular weight fractionation by size‐exclusion chromatography (SEC) is covered next, followed by a section on the versatile field flow fractionation (FFF). Large‐scale fractionation of polymers is covered in the section for continuous polymer fractionation (CPF). Mass spectrometry, particularly matrix‐assisted laser desorption ionization coupled with time‐of‐flight analyzers (MALDI‐TOF) is the subject of the next section. Finally, a section in interaction chromatography and some other less general polymer fractionation techniques is followed by the concluding section on cross‐fractionation techniques.
Polypeptide Synthesis, Solid‐Phase Method
Authors: Barany George , Kneib‐Cordonier Nancy , Mullen Daniel G.
Published: July 2004

Solid‐phase peptide synthesis (SPPS) has continued to evolve since originally conceived by R.B. Merrifield in 1959. This article is a general introduction into the current state of the art of SPPS. The review covers synthesis strategies, including protecting group combinations, coupling chemistry, monitoring, solid supports, cleavage, and purification. The most troublesome side reactions are also covered. Finally, the prognosis for future developments in SPPS is discussed.
Polypeptide Synthesis, Ring‐Opening Polymerization of α‐Amino AcidN‐Carboxyanhydrides
Authors: Klok Harm‐Anton
Published: July 2004

The ring‐opening polymerization of α‐amino acidN‐carboxyanhydrides (NCAs) represents the most convenient pathway for the large‐scale synthesis of polypeptides. Traditional initiators for the NCA ring‐opening polymerization include a variety of nucleophiles and bases. NCA polymerizations initiated by such initiators, however, proceed along multiple concurrent pathways, which hampers precise control over molecular weight, molecular weight distribution, composition, and architecture of the resulting polypeptides. A second parameter, which is of critical importance for the polymerization of NCAs, is monomer purity. This contribution provides an overview of the current methods for the synthesis and polymerization of NCAs. In addition to the traditional methods for NCA synthesis and polymerization, several recent developments are discussed that allow controlled/“living” polymerization of NCAs and facilitate the synthesis of structurally well‐defined polypeptide architectures.
Rubber Compounding
Authors: Rodgers Brendan , Waddell Walter H. , Klingensmith William
Published: July 2004

Rubber compounding is the complex, multidisiplinary science of selecting and blending the optimum combination of elastomer and other ingredients that meet the performance, processing, environmental, and cost requirements for rubber goods made and used in commerce. Chemical and physical properties of the wide variety of elastomers and ingredients available in making rubber goods are provided. Vulcanization, oils, plasticizers, general compounding, curing, fillers, latex, and testing are discussed.
Silk
Authors: Kaplan David L.
Published: July 2004

Silks are naturally spun fibrous proteins most often associated with silkworms and spiders. Silk fibers are unusual in combining strength, toughness, and resistance to mechanical compression. The proteins are characterized by a β‐sheet secondary structure for the highly crystalline regions, as well as regions of lower crystallinity. Silkworm cocoon fibers have been used in textiles for thousands of years. Silk production by spiders has not been domesticated to date. Water‐soluble silk proteins are synthesized and stored in glands until spun into fibers, via micellar and gel states, at which point they become insoluble in water upon spinning. The silk spinning process is regulated by the organism and involves the extrusion of the silk gel in a liquid crystalline state through spinnerettes. Silk fibers are mechanically stable to approximately 200°C. Membranes, hydrogels, fibers, and foams have been formed from reconstituted silks that provide useful means to explore structure development, to entrap enzymes, and for use as biomaterial scaffolds such as for tissue engineering. Worldwide production of silkworm silk for textiles is expected to increase, and future applications will depend on biotechnological approaches to generate suitable levels of specifically tailored silk compositions.
Sutures
Authors: Chu C. C.
Published: July 2004

Among wound closure biomaterials, sutures have the longest history, have received the most attention, and are the most widely used. A suture is a strand of material, either natural or synthetic, used to ligate blood vessels and to approximate tissue together. In this article, all aspects of suture‐based wound closure biomaterials, their classification, and chemical, physical, mechanical, biological, and biodegradation properties are concisely covered. Catgut and silk dominated the suture market until 1930. The introduction of steel wire and synthetic nonabsorbable fibers such as nylon, polyester, and polypropylene during and after World War II greatly expanded the chemical composition of suture materials. The introduction of absorbable suture materials in the 1970s opened a new milestone for suture materials. The most important advantage of synthetic absorbable sutures is their reproducible and predictable degradability inside a biological environment.
Transport Properties
Authors: Koros William J. , Madden William C.
Published: July 2004

This article covers the transport properties of gases, low activity vapors, and intermediate‐sized penetrants through rubbery, semicrystalline, and glassy polymers. The article emphasizes polymer transport properties under conditions of low to intermediate penetrant concentration where extraordinary differences can exist between the diffusivities of penetrants having relatively small differences in molecular size or shape. Nonideal transport effects, such as plasticization, clustering, and non‐Fickian transport, are covered. Particular attention is given to the nonequilibrium nature of glassy polymers and the resulting effects on penetrant transport. The recent development of positron annihilation lifetime spectroscopy (PALS) and molecular modeling of diffusion are described. Transport through porous polymers and reptation of macromolecules within a macromolecular matrix are not covered in this article.
Vinyl Acetate Polymers
Authors: Cordeiro Cajetan F. , Petrocelli Francis P.
Published: July 2004

This article provides information related to the chemistry, manufacture, and use of poly(vinyl acetate). Summary information is provided on vinyl acetate as the primary ingredient in the manufacture of the polymer. This information focuses on the chemical and physical properties of the material and the handling and safety aspects pertinent to its use in a polymerization system. The key material properties of poly(vinyl acetate) homopolymer and copolymers are described. The influences of key components of the polymerization recipe are discussed, such as the effect of the stabilizers, comonomers, and chain‐transfer agents on the reaction and product. Polymerization process aspects are covered with a focus on emulsion polymerization. The mechanisms involved in the vinyl acetate polymerization reaction are discussed. An overview is provided of the applications of the homopolymer and copolymers in adhesives, paint, paper, and other areas. General information is provided in these areas with references which can be used to obtain more specific information.
Degradable Polymers and Plastics in Landfill Sites
Authors: Swift Graham , Wiles David M.
Published: July 2004

Through the ages, landfill sites have been the repositories of human garbage. They were once prized sites for excavation to yield information of past cultures and civilizations. However, with the advent of the polymer and plastics age, what had once been an acceptable level of landfill waste of pottery, metals, and yard and agricultural debris became significantly larger in volume with the disposal of low density plastic waste from packaging and polymers from the ubiquitous disposable diapers, for example. This serious situation, of course, has had a very adverse effect on the number and capacity of landfill sites available for the disposal of all grades of trash. The very apparent limitation of available sites precipitated the waste‐management era, where alternative approaches were considered and developed to at least limit the problem. Some of these alternatives include recycling, incineration, and biodegradation under controlled environmental conditions such as composting. Not unexpectedly, the development of suitable polymers and plastics and the implementation of these alternatives is a slow process. Consequently, there are still huge amounts of plastic and polymer residues that are entering landfill sites every year. This article attempts to overview the issue and to summarize the limited evidence that we have on waste polymers and plastics as to their ultimate fate—recalcitrance, degradation, or biodegradation.
Scratch Behavior of Polymers
Authors: Wong Janet S. S. , Sue Hung‐Jue
Published: July 2004

Scratch and wear is a long existing deteriorating phenomenon occurring when two moving surfaces are in intimate contact. This problem in polymers has been emphasized because of the increasing popularity of polymers as the materials of choice in various applications. It is thus important for us to understand this phenomenon in order to engineer polymers with good scratch and wear resistance. This article focuses on the fundamental process that leads to abrasion and wear, ie, scratch behavior of polymers. The objective of this article is to highlight the importance of understanding scratch behavior of polymers by giving readers an up‐to‐date knowledge in this field of research. The theoretical framework concerning interfacial contacts and the experimental aspects in terms of methodology and quantitative measures is introduced. The effects of various material and testing parameters on the scratch behavior of polymers are summarized. Directions for future research are also suggested.
Melamine–Formaldehyde Resins
Authors: Binder Wolfgang H. , Dunky Manfred
Published: July 2004

Melamine‐based resins [MF, MUF, MUPF, PM(U)F] used as wood adhesives represent one of the largest groups of aminoplastic resins. They are made by the reaction of formaldehyde with melamine using urea, phenol, or other components as comonomers. The hardened resins show duroplastic hardening behavior; they are three‐dimensionally cross‐linked and hence insoluble, nonmeltable networks. Analytical methods to determine the chemical identity of the complex mixtures (ie, NMR spectroscopy, IR spectroscopy, HPLC, as well as mass spectrometry) are described in this article. Melamine‐based resins show higher hydrolysis resistance compared to UF resins. The field of application comprises the production of wood‐based panels such as particleboards, MDF, OSB, plywood, blockboards, and others especially for use under humid conditions. The molar ratio between formaldehyde/reactive amino groups [F/(NH2)2] distinctly determines reactivity, the degree of cross‐linking, and hence the bonding strength. Cocondensation between melamine, formaldehyde, and other components (such as urea and phenol) is possible, furnishing cocondensates with improved properties and reduced price.
Telechelic Polymers
Authors: Yagci Yusuf , Nuyken Oskar , Graubner Vera‐Maria
Published: July 2004

In this article common synthetic routes toward telechelics, which are polymers with well‐defined functional end groups, are described. Telechelic polymers are available via radical, cationic, and anionic polymerization including reversible addition–fragmentation chain transfer polymerization, atom transfer radical polymerization, and nitroxide mediated polymerization. Furthermore, metathesis has become a valuable tool for the preparation of telechelics. Last but not least selected examples are presented in which step‐growth polymerization has been successfully applied for the synthesis of such well‐defined macromolecules. In specific cases chain scission can also be a useful route.
Scanning Force Microscopy
Authors: Schönherr Holger
Published: July 2004

Scanning force microscopy (SFM) belongs to a class of real‐space microscopic techniques, which combine high spatial resolution, 3‐D imaging capabilities, and contrast mechanisms based on specific materials contrast. In particular, in the field ofpolymer science and technology, SFM quickly developed into an indispensable characterization technique and has found widespread use. In this article the application of SFM to polymers is discussed based on a selection of topics covering the whole breadth from topography imaging to mapping of surface properties and studies of dynamic processes in real time. The basic concepts and modes of SFM, as well as some rudimentary theory, are introduced as a self‐supporting basis for the following sections. The visualization of the morphology and ordering of polymers at various hierarchical levels is reviewed starting from the visualization of single macromolecules, chain packing, and surface crystal structures. The imaging of lamellar crystals, hedrites, and spherulites by SFM approaches is discussed, followed by studies of the effects of deformation and processing, as well as studies on the morphology of latex particles and fibers. The mapping of surface properties and composition in the heterogeneous and surface‐modified polymer systems via the spatially resolved measurement of adhesion and friction forces, as well as surface mechanical properties, are covered. The final section is focused onin situstudies of structure development and dynamic processes, including polymer crystallization, followed in real time by SFM.
Nonwoven Fabrics, Staple Fibers
Authors: Chapman Roger
Published: July 2004

This article provides an overview of the production methods, properties, and uses of nonwoven fabrics. The discussion includes a brief introduction, short history, and compilation of definitions of a nonwoven fabric. Staple fiber processes, including fiber selection, web formation, web layering, web consolidation, and finishing, are described. Descriptions and illustrations of the manufacturing sequences follow. Production trends and product applications are discussed.
Ultrasound‐Induced Radical Polymerization
Authors: Kuijpers Martijn W. A. , Kemmere Maartje F. , Keurentjes Jos T. F.
Published: July 2004

Sonochemistry comprises all chemical effects that are induced by ultrasound. Most of these effects are caused by cavitations, ie, the collapse of microscopic bubbles in a liquid. The chemical effects of ultrasound include the formation of radicals and the enhancement of reaction rates at ambient temperatures. For the development of sustainable polymer processes, ultrasound is an interesting technology, as it allows for polymerizations without the use of initiator. The radicals are generatedin situby cavitation events, which enable a clean and intrinsically safe polymerization reaction. As a result of the high strain rates outside the bubble, cavitation can also induce chain scission, which provides an additional means to control the molecular weight of the produced polymer. This article discusses the possibilities, mechanisms, and challenges of several types of ultrasound‐induced radical polymerizations.
Latex Technology
Authors: Grady Michael C.
Published: July 2004

Latices are colloidal dispersions of discrete polymer particles, usually in an aqueous medium. Technology used to make and use latex involves many aspects of colloidal and polymer chemistry. This article reviews the fundamentals of emulsion polymerization, the techniques used to make most synthetic latices, general properties of latices, as well as colloidal and polymer compounding ingredients to convert latices into useful products, and discusses the wide variety of applications in which latices are used.
Electron Spin Resonance
Authors: Schlick Shulamith , Jeschke Gunnar
Published: July 2004

This article begins with a description of the fundamentals of electron spin resonance (ESR) spectroscopy, with emphasis on the experimentally available parameters relevant for elucidation of the polymer structure, dynamics, transport, and stability. Advanced ESR methods, including high field and time‐domain ESR, and double resonance methods are then outlined. The part that describes the ESR methods concludes with an outline of the transition from ESR spectroscopy to ESR imaging.

Specific, and important, applications of ESR spectroscopy to polymeric systems follow: the use of CW ESR of nitroxide spin probes to describe the local polarity and dynamics in ion‐containing polymers; pulsed ESR methods for the characterization of the distribution and structural parameters of ion clusters in telechelic block‐copolymer based ionomers; and spatially resolved degradation in heterophasic polymers by 1‐D and 2‐D spectral‐spatial ESR imaging.

The article concludes with an evaluation of the strengths of ESR methods, and views on further applications of this approach and on areas that require further development.