Fluoropolymers commercial

Limited solubility in selected perfluorinated solvents (unique amongst commercial fluoropolymers), enabling solution-cast ultra-thin coatings in the submicrometre thickness range. 

There are several types of mesh available, and these are identified by mesh thickness, density, wire diameter and weave pattern. Table 4-9 identifies most of the commercial material now available. The knitted pads are available in any material that can be formed into the necessary weaves, this includes stainless steels, monel, nickel, copper, aluminum, carbon steel, tantalum, Hastelloy, Saran, polyethylene, fluoropolymer, and glass multi-filament. 

A classification by chemical type is given in Table 1. It does not attempt to be either rigorous or complete. Clearly, some materials could appear in more than one of these classifications, eg, polyethylene waxes [9002-884] can be classified in both synthetic waxes and polyolefins, and fluorosilicones in silicones and fluoropolymers. The broad classes of release materials available are given in the chemical class column, the principal types in the chemical subdivision column, and one or two important selections in the specific examples column. Many commercial products are difficult to place in any classification scheme. Some are of proprietary composition and many are mixtures. For example, metallic soaps are often used in combination with hydrocarbon waxes to produce finely dispersed suspensions. Many products also contain formulating aids such as solvents, emulsifiers, and biocides. 

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. 

Fluorocarbons and fluoropolymers have been in commercial use for over half a century and have found their way into a diverse array of products. The members of this array are too numerous to hst but they include nonstick coatings for cookware, construction materials, carpets, textiles, paints, electronic materials, household cleaners and personal hygiene products. As fluorocarbons are expensive compared to their hydrocarbon analogues, they are chosen carefully and usually to fill a void in a product attribute that simply cannot be accommodated by another material. The attributes typically afforded by the use of fluorocarbons are repellency, lubricity, chemical and thermal inertness, and low dielectric constant, in regards to which fluorocarbons are unique among their hydrocarbon counterparts. 

For some years a wide range of labware (e.g., flasks, vessels, Erlenmeyer flasks, syringes, separation funnels or even complete distillation apparatus) made of fluoropolymers (Table 4) has been commercially available and can be almost universally utilized over a temperature range of — 270 to + 260 C. Polyethylene and polypropylene can both be used for short periods, however, hydrogen fluoride can remove plasticizers from these polymers resulting in brittleness and also adversely affecting fluorinations. 

Indeed, free radical polymerization of fluoroolefins continues to be the only method which will produce high-molecular weight fluoropolymers. High molecular weight homopolymers of TFE, CFC1 = CF2, CH2CF2, and CH2=CHF are prepared by current commercial processes, but homopolymers of hexafluoro-propylene or longer-chain fluoroolefins require extreme conditions and such polymerizations are not practiced commercially. Copolymerization of fluoroolefins has also led to a wide variety of useful fluoropolymers. Further discussion of the subject of fluoroolefin polymerization may be found elsewhere and is beyond the scope of this review [213-215]. 

Registered Trade Names of Common Commercial Fluoropolymers... 

Fluoropolymers represent a rather specialized group of polymeric materials. Their chemistry is derived from the compounds used in the refrigeration industry, which has been in existence for more than 60 years. In the 1930s, efforts were made to develop nontoxic, inert, low boiling liquid refrigerants mainly for reasons of safety. The developed refrigerants based on compounds of carbon, fluorine, and chlorine, commonly known as freons, quickly became a commercial success. Eventually, they also became widely used as aerosol propellants. 

Monomers for commercially important large-volume fluoropolymers and their basic properties are shown in Table 1.1. These can be combined to yield homopolymers, copolymers, and terpolymers. The resulting resins range from rigid resins to elastomers with unique properties not achievable by any other polymeric materials. Details about the basic chemistry and polymerization methods are included in Chapter 2, fundamental properties of the resulting products are discussed in Chapter 3, and processing and applications in Chapter 4. 

FIGURE 3.2 Elongation values from commercial fluoropolymers (ASTM D638). (From Scheirs, J., in Modem Fluoropolymers, Scheirs, J., Ed., John Wiley Sons, New York, 1997. With permission.)... 

The glass transition temperature of PMTFPS is -75°C (-103°F). Moreover, it does not exhibit low-temperature crystallization at -40 C (-40°F) as PMDS does. Because of this and the low Tg, fluorosilicone elastomers remain very flexible at very low temperatures. For example, the brittleness temperature by impact (ASTM D 746B) of a commercial fluorosilicone vulcanizate was found to be -59°C (-74°F).62 This is considerably lower than the values typically measured on fluorocarbon elastomers. Fluorosilicones combine the superior fluid resistance of fluoropolymers with the very good low-temperature flexibility of silicones. 

The following fluoropolymers are commercially available in aqueous systems PTFE, PFA, MFA, FEP, ETFE, PVDF, THV Fluoroplastic, fluorocarbon elastomers, fluoroacrylates, and fluorinated polyurethanes. 

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