Fluoropolymers extruders

Atlas FA 10OH Atlas FA 10OS Aflas FA 150E Aflas FA 1 SOL Aflas FA 1 SOP fluoropolymer, extruded film Dyneon THV 220G fluoropolymer, glass fabric coatings Teflon PTFE 30B... 

The products of degradation of molten fiuoropoly-mers are highly corrosive, often containing hydrofluoric acid. It is important that the surfaces of machines that come in contact with molten fluoropolymers are constructed from special grades of corrosion-resistant metals. These metals are significantly more expensive than lower grades of steel. Corrosion of process surfaces can result in the contamination of the finished product and deterioration of its physical properties. Section 7.8 provides information about the metals and their suppliers that are recommended for the construction of the various parts of fluoropolymer extruders. 

Like many other fluoropolymers, Nafion is quite resistant to chemical attack, but the presence of its strong perfluorosulfonic acid groups imparts many of its desirable properties as a proton exchange membrane. Fine dispersions (sometimes incorrectly called solutions) can be generated with alcohol/water treatments. Such dispersions are often critical for the generation of the catalyst electrode structure and the MEAs. Films prepared by simply drying these dispersions are often called recast Nafion, and it is often not realized that its morphology and physical behavior are much different from those of the extruded, more crystalline form. 

FIGURE 4.9 Vertical ram extruder, main components. (Courtesy of AG Fluoropolymers.)... 

With developments in equipment and the fluoropolymers that have high melt viscosities, the maximum extrusion rate using screws is normally limited by melt fracture. However, these plastics have exceptional melt strength. This characteristic makes possible ram extruding using a die with a large opening and apply a draw down of the extrudate to the desired insulation thickness. 

Miscellaneous Extrusion-Applied Polymers. As mentioned earlier, there is a tendency to develop solventless magnet wire enamel formulations, and extrudable polymer systems would fulfill that requirement. There have been reports about extrusion of thin coatings of polyesters over copper wire. At this point, the state of the art allows extrusion of thin insulating films only with thermoplastic materials. The reliable extrusion of uniform and concentric insulating films of approximately 0.001-0.002 in. wall thickness is already an improvement over the more traditional extrusions of polyethylene, poly(vinyl chloride), and several fluoropolymers in much greater wall thicknesses. Because cross-linked insulation is ultimately required for most magnet wire applications, further materials development needs to be done to provide polymer compositions that are both extrudable as thin films and can be cross-linked in an economical process suitable for large-scale industrial application. 

Table 5.5. Recommended Tooling and Processing Conditions for Extruding E223 Constructions of Teflon CFP 6000 Fluoropolymer Resin ...

Anthony, P. V., Extrusion of Fluoropolymer in a Melt Processable Extruder, Chemical Engineering World, XXIX(4) (Apr. 1994)... 

Another, more common commercial use of the phenomenon is the addition of fluoropoly-mers to polyolehns. In this case, a small amount of fluoropolymer progressively migrates to the die surface, reducing the die pressure drop and making it possible to extrude the resin at high throughput without the melt fracture. It has been shown that this approach also works for other polymers, viz. PEEK. Thus, blends of PEEK with polytetrafluoroethylene, 1-5 wt% PTFE, were extruded. The pressure drop across the die was reported to decrease with time to an equilibrium value, R.. The value of P,. depended on PTFE content, whereas the time to reach it depended on the rate of extrusion — the higher was the rate, the shorter was the saturation time [Chan et al., 1992]. 

Fluoropolymers have been used as processing aids because small quantities can reduce signih-cantly the overall viscosity and thus facilitate extrusion. Feng et al. [1996] examined the mechanism of viscosity reduction in the capillary flow of HDPE/fluoroelastomer blends. X-ray photoelectron spectroscopy, used to characterize the composition of the extmdates surface, indicated only very small traces of the fluoroelastomer on the extrudate, pointing to the fact that the viscosity reduction is due to adhesive failure between the fluoropolymer layer and HOPE. 

All three commercial amorphous fluoropolymers. Teflon AF, Hyflon AD, and Cytop posses a unique set of properties. All dissolve in fluorinated solvents and thus may be spin coated to produce thin hlms and coatings. The polymers may also be extruded and molded using traditional polymer processing techniques. Note that the polymers are not soluble in hydrocarbon solvents or water and retain the chemical and thermal stability of perfluorinated polymers such as Teflon . These polymers have lower density than the well-known semicrystalline perfluorinated polymers such as pTFE that results in lower refractive index, lower thermal conductivity, higher gas permeability, and lower dielectric constant. The polymers are transparent and have excellent mechanical properties below their Tg due to their amorphous character. The presence of a heterocyclic ring in the polymer backbone of these materials is key... 

Plastics find extensive use in several areas of fiber optic cables. Buffer tubes, usually extruded from high-performance plastics such as fluoropolymers, nylon, acetal resins, or polybutylene terephthalate (PBT) are used for sheathing optical fibers. A blend o PVC and ethylene vinyl acetate (EVA) polymer, such as Pantalast 1162 of Pantasote Incorporated, does not require a plasticizer, which helps the material maintain stability when in contact with water-proofing materials. PVC and elastomer blends, Carloy 6190 and 6178, of Cary Chemicals are also used for fiber optic applications (Stiffening rods for fiber optics are either pultruded epoxy and glass or steel. Around these is the outer jacketing, which is similar to conventional cable.)... 

Uses Fluoropolymer tor extruded films, tubes, profiles, and wire coatings Features For applies, requiring highest level of flexibility, transparency, low temp, fusion or bonding capability with mod. chem. resist. exc. weath-erability and good antisoiling props. 

Uses Fluoropolymer for extruded films, tubes, profiles, wire coatings, laminated films... 

The polymer in this sulfonyl fluoride form is thermoplastic and can be melt processed with conventional fluoropolymer processing equipment. For use in chlor-alkali electrolyzers, the polymer is extruded to film form and reinforced, if necessary, with... 

Fluoropolymers are now being developed which are resistant to a very wide range of acids and solvents and have a high thermal capability, up to 200 °C. They can, in most cases, be extruded moulded or applied by spraying, electrostatic coating or by fluidized bed technique. Some of the materials are listed here for reference Polyvinyli-dene Fluoride (PVF2), or (PVDF) Fluorinated Ethylene Propylene (FEP). 

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