Melt-processible fluoroplastics, processing copolymers

Other melt-processable fluoroplastics include ethylene-chlorotrifiuoroethylene (ECTFE) copolymer (melting point 240°C), polyvinylidene fluoride (PVDF) (melting point 170°C), and polyvinyl fluoride (PVF), which is commercially available only as film. 

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. 

TFE and VDF can be polymerized in any proportion, thus giving rise to a broad variety of products. The copolymers are obtained in either emulsion or suspension process. An approximate composition of TFE PVDE of 20 80 is the eutectic point in the system, with a melting point of 120 ° C. It is widely used as a technical polymer and is available under the brand names Kynar 7200 and Kynar SL (Pennwalt Corporation). A composition with the an approximate composition of TFE PVDF 29 71) is available as Fluoroplast 42 (Russia). Both copolymers are soluble in ketones and esters but are insoluble in alcohols and chlorinated hydrocarbons and are mainly processed via melt extrusion at temperatures between 190 and 260 °C [27, 28]. The low-wave-number FTIR spectrum of the copolymer is depicted in Figure 3.13. 

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