Fluoropolymers family

The fluoropolymer family consists of polymers produced from alkenes in which one or more hydrogens have been replaced by fluorine. The most important members of this family are polytetrafluoroethylene (PTFE) (XLVII), polychlorotrifluoroethylene (PCTFE) (XLVIII), poly(vinyl fluoride) (PVF) (XLIX), poly(vinylidene fluoride) (PVDF) (L) copolymers of... 

Poly(vinylidene fluoride) (PVDF) is the second most important thermoplastic within the fluoropolymer family after PTFE. Although, both the thermal and chemical stability of PVDF are somewhat lower compared to PTFE, the hydrogenated polymer can be more easily processed with conventional equipment, and it offers an advantageous compromise between quality and price. When the... 

Fluoropolymers are chemically stable and inert or relatively unreactive. Reactivity, generally, decreases as the fluorine content of the polymer increases. Fluorine induces more stability than chlorine. The fluoropolymer family of plastics has low toxicity and almost no toxicological activity. No fluoropolymers have been known to cause skin sensitivity and irritation in humans. Polyvinyl fluoride contains one fluorine atom and three hydrogen atoms per monomer unit and has been shown to cause no skin reaction in human beings.Excessive human exposure to fluoropolymer resin dust resulted in no toxic effects, although urinary fluoride content increased. 

As depicted in this chapter, specific structural and electronic properties of fluo-ropolymers have made them the polymers of choice to be used in SC-CO2. The study of different families of fluoropolymer demonstrated that, apart from the effect of polymer architecture and CO2 density, the lowering of polymer-polymer interactions appeared as the main critical parameter to improve polymer solubility. Moreover, the use of those polymers as building blocks to design macromolecular surfactants allows the successful formation of micelle-like structures or the formation of emulsions in the presence of additional water. Based on this knowledge, development of new fluoropolymer families will surely pave the way for the preparation of stable W/SC-CO2 emulsions with great promise for the development of environmental-friendly chemical processes in diverse fields of organic and inorganic synthesis and polymerization. 

A good review on fluoropolymers was published in 2009 [85], Fluoropolymers (olefinic) are classified as perfluorinated and partially fluorinated products. The former are homo and copolymers of TFE. The speciality fluorinated polymers include perfluoroethers, fluoroacrylates and fluoro silicones, which are used in significantly smaller volumes than olefinic fluoropolymers. The most important monomers are TFE, VDF, ethylene and CTFE. Figure 11.11 highlights fluoropolymers family tree. 

Another impetus to expansion of this field was the advent of World War 11 and the development of the atomic bomb. The desired isotope of uranium, in the form of UF was prepared by a gaseous diffusion separation process of the mixed isotopes (see Fluorine). UF is extremely reactive and required contact with inert organic materials as process seals and greases. The wartime Manhattan Project successfully developed a family of stable materials for UF service. These early materials later evolved into the current fluorochemical and fluoropolymer materials industry. A detailed description of the fluorine research performed on the Manhattan Project has been pubUshed (2). 

Core technical competencies may be composed of a number of core or key technologies. The competencies in turn can support product families, platforms, or core products, which then support individual products. These products may ultimately be found in a number of forms or shapes. For example, a key technology such as polymer characterization may support a competency in polymer synthesis and architecture, which in turn supports the platform of fluoropolymers and the product family of Teflon (DuPont) fluoropolymer resins that can be found as films, fibers, or in other forms. 

Teflon AF A Family of Amorphous Fluoropolymers with Extraordinary Properties... 

Amorphous polymers characteristically possess excellent optical properties. Unlike all the other commercially available fluoropolymers, which are semicrystalline, Teflon AF is quite clear and has optical transmission greater than 90% throughout most of the UV, visible, and near-IR spectrum. A spectrum of a 2.77-mm-thick slab of AF-1600 is shown in Figure 2.5. Note the absence of any absorption peak. Thin films of Teflon AF have UV transmission greater Ilian 95% at 200 mm and are unaffected by radiation from UV lasers. The refractive indexes of Teflon AF copolymers are shown in Figure 2.6 and decrease with increasing FDD content. These are the lowest refractive indexes of any polymer family. It should be noted that the abscissa could also be labeled as glass transition temperature, Tg, since Tg is a function of the FDD content of the AF copolymer. Abbe numbers are low 92 and 113 for AF-1600 and AF-2400. 

Teflon AF is truly a family of amorphous fluoropolymers with an extraordinary combination of properties. All of the excellent properties of die existing fluoropolymers have either been retained or improved upon and properties arising from the amorphous nature and the presence of microvoids in the AF family of polymers have been added. The similarities and differences of AF and other Teflon polymers are summarized in Table 2.3. This unique combination of properties of Teflon AF amorphous fluoropolymers makes them well suited for applications that had previously precluded polymeric materials,... 

Fluoropolymers. These form one of our oldest and most spectacular families of engineering plastics. Polytetrafluoroethylene was developed by DuPont over two decades ago, and more recently by Allied Chemical, Hoechst, ICI, Pennwalt, and other manufacturers as well. It combines unusually low adhesion and friction, high temperature and flame resistance, excellent electrical properties, and extreme chemical inertness. Its high melting point and melt viscosity make thermoplastic processing extremely difficult, so that many... 

Fluorine contamination has been reported in various environments and applications in the past. It has shown up in plasma processing [10-18], as crosscontamination from storage in contaminated containers or with contaminated samples [14,18], and modification of aluminum deposited on fluoropolymer substrates and other polymers having fluorine-based plasma treatments has also been observed [19-21]. Fluorocarbon lubricants have also been noted to modify the oxide structures on aluminum alloys [22,23], and the degradation of AI2O3 catalytic supports has been associated with fluoride conversion during reactions with fluorocarbons [24]. Alloy oxide modification has also been well noted in the presence of fluorine compounds not of the fluorocarbon family [25]. 

Fluoropolymers can be injection-molded in plunger or ram-type equipment but a screw machine works best with this family of plastics. The screw-type injection molding machines have a number of advantages including those listed in Table 6.23. Various components of screw-type machines for processing fluoropolymers are described in this section. 

Applications of fluoropolymers are still growing, even decades after the discovery of the first plastic (polytetrafluoroethylene) in this family. The increasing use of fluoropolymers in such dynamic industries as wire and cable insulation, automotive, aerospace, oil and gas recovery, and semiconductor manufacture has led to significant material developments and trends in the last few years. New fluoropolymers have been introduced to the market (amorphous fluoroplastics, modified PTFE, low-temperature fluoroelastomers, and amine-resistant fluo-... 

Fluoropolymers are a family of polymers containing C-F bonds. Polytetrafluoro-ethylene (PIPE) has the following structure ... 

In addition to Nafion, the family of sulfonated fluoropolymers includes Dow chemical membranes and Membrane C. Weber and Newman predict that the clusters formed within Dow membranes are smaller than in Nafion due to the higher elastic deformation energy [27]. For sulfonated polyetherketone membranes, which are under investigation due to their potential in lowering costs, separation into hydrophobic and hydrophilic domains is not as well defined as in Nafion [28]. As a result, their structure consists of narrower channels and clusters that are not as well connected as in Nafion [27, 28]. 

Fluoropolymers (PTFE and Other Polymers in the Teflon Family) 404... 

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