Melt-Processible Perfluoroplastics

The melt processible fluoroplastics are often desired due to the cost benefits of melt extrusion over paste extrusion. FEP, PEA and specially formulated melt processible perfluoroplastics are used in many of these applications however, in some of these applications, perfluoroplastics may not be the ideal choice. In cases where high cut-through resistance and better tensile properties are required, it is often desirable to employ a partially fluorinated polymer such as ETFE (ethylene-tetrafluoroethylene). ETFE is the copolymer of ethylene and TEE [16] that normally includes an additional termonomer to increase the flexibility required in commercial applications [17]. The increased physical and electronic interactions of the ETFE polymer chain are responsible for the comparatively enhanced physical properties. Additionally, the partially fluorinated polymers may be cross-linked to further improve physical properties. These benefits, however, are obtained at the expense of the unique properties of perfluoroplastics discussed in the Introduction and Overview. 

The melt processible perfluoroplastics highlighted in the above sections are often polymerized in totally aqueous media and are therefore available as aqueous dispersions of perfluoroplastic particles with a mean volumetric particle size of 150 to... 

Except for a small introduction in the section on aqueous dispersions, high MW PTFE is one perfluoroplastic which is not covered in this chapter. This is because, in the strictest sense, resins of high MW PTFE are not melt processible. Granular PTFE resins are processed by sintered metal technology techniques. PTFE fine powders are processed by paste extrasion techniques. The structures created with the use of these resins can be quite similar to melt processible perfluoroplastic parts or can be very... 

High MW PTFE tends to be favored in applications where the potential for extreme temperatures, harsh chemicals, and other extremely aggressive environments exist. This is particularly true when combined with high frequency requirements such as coaxial cable applications where the excellent dielectric properties are also required. Unfortunately, such FITE cannot be processed by conventional melt processing techniques. With the recent developments in foamed perfluoroplastic products, economical cables with properties very near to those of expanded PTFE are possible. 

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