File Name: processing and finishing of polymeric materials volume 2 .zip
- Specific Features of Turning Parts Made of Polymer Materials
- Aqueous processing in materials science and engineering
- Processing and Finishing of Polymeric Materials, 2 Volume Set (eBook, PDF)
- Processing and Finishing of Polymeric Materials, 2 Volume Set
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Specific Features of Turning Parts Made of Polymer Materials
E-mail: rdams1 mmm. An overview is given of fluorinated monomers, building blocks, oligomers and polymers, their industrial production and some of their applications. Functional perfluoropolyethers, functional meth acrylate oligomers and their applications in low surface energy coatings are areas of special attention.
Environmental aspects of fluorinated emulsifiers, used during fluoropolymer manufacturing and recycling of fluorinated materials with the ultimate goal of closing the fluorine cycle, are reviewed. In the early s, researchers of IG-Farbenindustrie in Frankfurt Germany studied systematically the first polymerizations of fluoroethenes; the Hoechst researchers had already prepared polychlorotrifluoroethylene PCTFE and polytetrafluoroethylene PTFE , including copolymers, recognizing the outstanding properties of these polymers.
DuPont de Nemours while investigating fluorinated refrigerants. The unique properties of PTFE were recognized during the Manhattan Project, where there was an urgent need for a material that would withstand the highly corrosive environment during the process of separating the isotopes of UF 6 for the first atomic bomb. PTFE apparently fulfilled all the needs, spurring the development of processing and production methods for this unique polymer.
DuPont de Nemours under the trade name Teflon. During the following decades, many fluoropolymers, including fluorothermoplastics and fluoroelastomers, were developed. Many synthetic routes to oligomers have been described, including radical oligomerization, oligocondensation, ionic oligomerization and ring-opening reactions. In Sections 1. Some of these manufacturing processes are fairly energy consuming e. Also, special care has to be taken in producing and handling TFE owing to its tendency to self-decompose into carbon and tetrafluoromethane.
In Table 1. A key-intermediate in the preparation of vinyl ethers and their oligomers is hexafluoropropylene oxide HFPO. HFPO is prepared from HFP via direct oxidation with oxygen, by electrochemical oxidation or by reaction with hypochlorides or hydrogen peroxide: 8.
HFPO reacts readily with nucleophiles; for example, in the presence of fluoride salts e. Other important perfluorinated vinyl ethers are synthesized by reaction of fluorinated alkoxides with HFPO followed by pyrolysis; the fluorinated alkoxides are usually prepared in situ from the corresponding acid fluorides Scheme 1.
An attractive, alternative route to perfluoro methyl vinyl ether PMVE is based on the reaction of perfluoromethyl hypofluoride and dichlorodifluoroethene followed by dehalogenation Scheme 1. Starting materials with functional groups can be prepared by direct or electrochemical fluorination ECF or by standard synthesis 10 Scheme 1. The synthesis of comonomers for the preparation of perfluorinated amorphous polymers with high glass transition temperatures T g involves multiple steps and has recently been described in detail 11 Figure 1.
The perfluorinated chain may contain from one up to 16 carbon atoms. Telomer iodides and the carbonyl and sulfonyl fluorides can be converted on an industrial scale into alcohols and meth acrylate monomers.
The first surfactants and textile treatments, containing perfluoroalkyl chains, were commercialized by 3M in the s. In the late s, PFOS and related compounds were identified at parts per billion levels in the sera of the general population.
During the following years, new materials based on C 4 F 9 technology that addressed the bioaccumulation and toxicity concerns associated with longer chain functional perfluoroalkyls, were developed and commercialized in selected markets. Many of the functionalized fluorinated oligomers used on an industrial scale are made by ring-opening reactions of HFPO, photo-oxidation of fluoroolefins and telomerization of fluorinated meth acrylates with functional mercaptans.
Their synthesis is summarized in Scheme 1. These PFPE carbonyl fluorides can be further converted into other functional groups, such as hydroxy, meth acrylate, nitrile and trialkoxyalkylsilane. The synthesis of functionalized fluorinated oligomers can be carried out by radical oligomerization of acrylic monomers in the presence of a functional mercaptan, such as 2-mercaptoethanol.
The synthesis is summarized in Scheme 1. Using the same synthetic procedure, mixed co-oligomers can also be prepared using fluorine-free hydrophilic and hydrophobic comonomers. Functional oligomers can be reacted and blended with many different compounds through their functional group s. For example, fluorinated oligomeric alcohols can be used in combination with isocyanates to make poly urethanes 24,26 or in combination with carboxylic acids to make poly esters.
Fluorochemical oil and water repellents for textile fabrics were discovered in the s by researchers at 3M 34 and, since then, many commercial products have been developed for a wide variety of surfaces by different companies.
Water and oily substances will not be able to wet and spread on such a treated surface, resulting in water and oil repellency of the treated fabric 38 Figure 1. Many fluorine-containing repellents are based on poly meth acrylates. These acrylic polymers can be visualized as consisting of pendant perfluoroalkyl groups R f and hydrocarbon groups R h , an acrylic polymer backbone and non-fluorinated linkages between the two.
The composition and ratio of the comonomers in such polymers affect the repellent properties. Comonomers with a crosslinking function, such as 2-hydroxyethyl acrylate, glycidyl methacrylate or N -methylolacrylamide, are used to increase the durability of the repellent treatment. It was observed that organizing the fluorinated groups, R f , into small domains improves their efficiency and effectiveness as oil and water repellents.
Much of the research and development work at 3M involved the combination of hydroxy-functionalized oligomers with isocyanates and fluorine-free mono-, di- or polymeric alcohols, amines, thiols and other isocyanate-reactive materials to form urethanes, ureas, thioureas or their polymeric analogs such as polyurethanes. Crosslinking of such urethane derivatives can be achieved by incorporating specific blocking agents such as oximes or imidazoles, thus forming thermolabile urethane groups. An interesting class of isocyanate-derived repellents are polycarbodiimides, 40,41 since the carbodiimide group, —N C N—, itself can react with functional groups present at the surface of the textile fabric.
Another important finding was the discovery of functionalized fluorinated spacer oligomers, prepared by radical oligomerization of spacer monomers with functional mercaptans. Fluorochemical textile treatments provide excellent oil and water repellency and stain-repellent finishes, but for the release of soil and stains, water needs to displace the contaminants and the laundering detergent must be able to wet the fabric. Fluorinated silanes have the ability to form chemical bonds with the hydroxy groups present on the glass through the formation of Si—O—Si bonds.
Perfluoro polyether silanes can be easily prepared by reaction of the corresponding esters with aminopropyltrialkoxysilanes 45 or the corresponding alcohols with isocyanatopropyltrialkoxysilanes. These silanes can be easily applied to siliceous surfaces, such as shower panels or bathroom ceramics, by applying dilutions in alcohols, such as ethanol or 2-propanol, in combination with catalytic amounts of acid.
In a first step, the trialkoxysilanes are hydrolyzed into silanols, which then undergo condensation reactions silanols reacting with themselves and crosslinking, where the fluorochemical is chemically bonded to the hydroxy groups of the siliceous surface.
The PFPE layer is very thin about 20— nm and provides excellent repellent and easy-to-clean properties and very good durability against aggressive chemicals, such as acids or bases, and against mechanical abrasion. Methods for aqueous delivery of PFPE-silanes were also developed. One method consists of making a non-aqueous concentrate containing the PFPE-silane and a fluorosurfactant, diluting the concentrate in water and applying the aqueous formulation to the siliceous surface.
A wide variety of fluoropolymers have been developed and produced on an industrial scale for a broad range of applications. Starting materials include low molecular weight perfluoro polyether dinitriles , such as shown in Figure 1. The principal method for synthesizing fluoropolymers is free-radical polymerization, as other typical methods, e.
Fluoroolefins can be polymerized using anionic catalysts, but termination by fluoride ion elimination prevents the formation of high molecular weight polymers.
Coordination catalysts do not lead to polymerization of fluoroolefins. The free-radical polymerizations are mostly water based, either as aqueous suspension polymerization mostly applied for PTFE polymers or as aqueous emulsion polymerization in the presence of emulsifiers, most preferably in the presence of fluorinated emulsifiers. In early times, radical copolymerization of fluorinated olefins in chlorinated fluorocarbon solvents e. Owing to the high emissions of these ozone-depleting solvents and to the Montreal Protocol, these processes had to be changed so as to use either environmentally friendly solvents [ e.
Polymerization in supercritical sc media e. Table 1. Details of polymerization, processing and product properties are provided in some excellent review articles. Alternating copolymers of HFIB hexafluoroisobutylene and VDF have been prepared, offering outstanding creep resistance and excellent mechanical and chemical properties; however, these copolymers have not attracted much commercial interest.
Important ionomers are shown in Figure 1. The main application is in coatings. In Asia, there is a capacity of more than tonnes available.
Owing to the outstanding, unique product properties, fluoropolymers are indispensable materials and consequently their socioeconomic value is extremely high. Fluoropolymers are now serving highly demanding applications in a diverse range of industries, which no other class of polymers can achieve Table 1.
For decades, the ammonium salts of perfluorooctanoic acid PFOA and perfluorooctylsulfonic acid PFOS have been used in aqueous emulsion polymerization to produce fluoropolymers cf. Section 1. With the recognition of the environmental and health concerns associated with long-chain functional perfluoroalkyls, fluoropolymer manufacturers began the development of alternative emulsifiers and different polymerization techniques using less or no fluorinated emulsifier. The challenge was to insure that fluoropolymers could still be safely manufactured while minimizing emulsifier emissions and use.
Ultimately, the goal became the replacement of PFOA and related materials with emulsifiers that had an improved hazard profile and still met polymerization process needs. The initiative also suggested that manufacturers replace these substances in their manufacturing processes with compounds having an improved toxicity and ecotoxicity profile or, even better, develop polymerization techniques that require less or no fluorinated emulsifier.
Meanwhile, most fluoropolymer manufacturers have been pursuing PFOA replacements. According to the literature, different PFOA replacements have been reported by the companies mentioned in Figure 1. By the mids, a large-scale facility to recover PFOA from off-gas streams was implemented by using scrubbing systems. During the following years, large-scale units to recover PFOA from aqueous waste water streams and aqueous fluoropolymer dispersions, using anion-exchange methods, were implemented; a recycling facility to reuse the recovered PFOA was installed in parallel.
Increased environmental awareness requires the complete life cycle of products to be considered, and consequently recycling of polymers comes into the focus. There are numerous different sources and different types of fluoropolymers for recycling purposes. Consequently, one has to consider these issues from various angles. The amounts of scrap, wet waste materials and off-specification materials of unfilled PTFE from manufacturers are usually in the lower percentage range.
The large amounts of waste are due to the very specific processing technologies for PTFE molding, sintering, machining and cutting. For unfilled PTFE resin, three established recycling paths exist today: Sintered, unfilled PTFE resin is cleaned from all contaminants and milled into certain particle size classes, which can be reused e. Such processes are used on a commercial scale.
Alternatively, clean and unfilled PTFE can be degraded by high-energy radiation such as with X-ray, gamma-ray or electron beam techniques. After irradiation, the material is milled to the desired particles size. In contrast to clean, unfilled PTFE, where some recycling opportunities are well established and the recycling rates reach a significant level, there are no large-scale recycling technologies for PTFE compounds.
This is primarily due to the presence of a large variety of different fillers e. Nearly all of these materials are recycled back into the corresponding processes; the end-use properties are almost unaffected.
In some cases, used perfluorinated fluoropolymers e. Perfluorinated thermoplastics e. PFA are reused in applications where the quality requirements e.
Overall, the major share of used fluoropolymers ends up in landfills, in incineration plants or in blast furnaces.
Communal waste incinerators can tolerate only very limited amounts of fluoropolymers owing to the high corrosiveness of the hydrofluoric acid formed during the process. In the past, many attempts were made to recover perfluorinated monomers from waste materials.
Aqueous processing in materials science and engineering
Please note that we only supply polymer in granular form for Injection Moulding or Extrusion applications. We do not supply polymer in rod, sheet or block form. Our team are available from 8am-5pm and we always aim to get back to you the same day. If you would rather contact us immediately please join us on live chat or give us a call on The conversion of raw polymers into finished products involves a series of polymer manufacturing processes. The first step consists of mixing additives into the polymer to achieve the required modification to the properties of the raw polymer. The second stage is to create the desired shape.
The application of the turning of parts made of polymer materials is considered. The choice of materials for the cutting part of the tools, their geometric parameters, the purpose of technological conditions, and cutting forces are discussed with allowance for the properties of polymer materials that characterize their machinability. The differences between the machining of parts made of polymeric materials and the processing of metal products are revealed. The ways of expanding the technological capabilities of machining of polymeric materials are shown. This is a preview of subscription content, access via your institution. Rent this article via DeepDyve.
Processing and Finishing of Polymeric Materials, 2 Volume Set (eBook, PDF)
Fluoroplastics, Volume 2: Melt Processible Fluoropolymers - The Definitive User's Guide and Data Book compiles the working knowledge of the polymer chemistry and physics of melt processible fluoropolymers with detailed descriptions of commercial processing methods, material properties, fabrication and handling information, technologies, and applications, also including history, market statistics, and safety and recycling aspects. Both volumes of Fluoroplastics contain a large amount of specific property data useful for users to readily compare different materials and align material structure with end use applications. This new edition is a thoroughly updated and significantly expanded revision covering new technologies and applications, and addressing the changes that have taken place in the fluoropolymer markets. Professionals involved in polymer manufacturing and part fabrication.
Reviews of aqueous processing in JOM have traditionally focused on hydrometallurgical process routes. This article, however, addresses the application of aqueous processing in materials engineering and presents some promising developments that employ aqueous-based routes for the manufacture of high-tech components and specialty products. Such applications include producing metallic and ceramic powders; etching; surface modification by electroplating and electroless plating; manufacturing jewelry and intricate components by electroforming; and producing advanced ceramics, composites, and nanophase materials by sol-gel and biomimetic processing.
Correspondence should be addressed to Faheem Uddin; dfudfuca yahoo. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The use of clay mineral in modifying the properties of polymeric material is improved in application.
Processing and Finishing of Polymeric Materials, 2 Volume Set
E-mail: rdams1 mmm. An overview is given of fluorinated monomers, building blocks, oligomers and polymers, their industrial production and some of their applications. Functional perfluoropolyethers, functional meth acrylate oligomers and their applications in low surface energy coatings are areas of special attention. Environmental aspects of fluorinated emulsifiers, used during fluoropolymer manufacturing and recycling of fluorinated materials with the ultimate goal of closing the fluorine cycle, are reviewed.
Not a MyNAP member yet? Register for a free account to start saving and receiving special member only perks. Materials as a field is most commonly represented by ceramics, metals, and polymers. While noted improvements have taken place in the area of ceramics and metals, it is the field of polymers that has experienced an explosion in progress. Polymers have gone from being cheap substitutes for natural products to providing high-quality options for a wide variety of applications. Further advances and breakthroughs supporting the economy can be expected in the coming years.
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By Wiley. An authoritative reference on the processing and finishing of polymeric materials for scientists and practitioners. Owing to their versatility and wide range of applications, polymeric materials are of great commercial importance. Manufacturing processes of commercial products are designed to meet the requirements of the final product and are influenced by the physical and chemical properties of the polymeric material used. Based on Wiley's renowned Encyclopedia of Polymer Science and Technology , Processing and Finishing of Polymeric Materials provides comprehensive, up-to-date details on the latest manufacturing technologies, including blending, compounding, extrusion,molding, and coating.
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