ECTFE electrical properties

Fluoroplastic FPs have superior heat and chemical resistance, excellent electrical properties, but only moderate strength. Variations include PTFE, FEP, PFA, CTFE, ECTFE, ETFE, and PVDF. Used for bearings, valves, pumps handling concentrated corrosive chemicals, skillet linings, and as a film over textile webs for inflatables such as pneumatic sheds. Excellent human-tissue compatibility allows its use for medical implants. 

Examples of fluoroplastics include polytetrafluoroethylene (PTFE), fluorinated ethylene propylene (FEP), ethylene—chlorotrifluoroethylene (ECTFE), ethylene—tetrafluoroethylene (ETFE), poly(vinylidene fluoride) (PVDF), etc (see Fluorine compounds, organic). These polymers have outstanding electrical properties, such as low power loss and dielectric constant, coupled with very good flame resistance and low smoke emission during fire. Therefore, in spite of their relatively high price, they are used extensively in telecommunication wires, especially for production of plenum cables. Plenum areas provide a convenient, economical way to run electrical wires and cables and to interconnect them throughout nonresidential buildings (14). Development of special flame-retardant low smoke compounds, some based on PVC, have provided lower cost competition to the fluoroplastics for indoors application such as plenum cable, Riser Cables, etc. 

Halar ECTFE (ethylenechlorotrifluoroethylene) This material is an alternating copolymer of ethylene and chlorotrifluroethylene. This fluoropolymer withstands continuous exposure to extreme temperatures and maintains excellent mechanical properties across this entire range (from cryogenic temperatures to 180°C). It has excellent electrical properties and chemical resistance, having no known solvent at 121°C. It is also nonbuming and radiation-resistant. Its ease of processing affords a wide range of products. 

Some electrical properties of ECTFE are given in Table 3.80. The dielectric strength (ASTM D149) is higher than the breakdown strength of PVDF. 

Table 3.80. Typical Electrical Properties of ECTFE Film at 23°C[ i...

The exterior of foamed wire insulation can be coated with a solid layer (jacket) of ETFE or ECTFE for wires used in telecommunications and fiber optics. This arrangement allows the foamed perfluoro-polymer to provide good electrical properties while the skin layer supplies sufficient mechanical properties. A foamed FEP wire insulation (eore), with a thickness of 0.5 mm, was coatedl with 51 pm of an ETFE jacket it had a dielectric constant of 1.64 and dielectric breakdown strength of 26.6 kV/mm. 

Some of the electrical properties of ECTFE are given in Table 13.39. The dielectric strength (per ASTM D149) is higher than breakdown strength of PVDF. The dielectric constants and dissipation factors of ECTFE, PVDF, and PTFE are given in Figs. 13.91 -13.96 as a function of temperature and frequency. 

Ethylene chlorotrifluoroethylene copolymer (ECTFE, E/CTFE) n. A fluoroplastic with good mechanical, thermal, electrical, processing, and resistance properties. 

Wires have been insulatedl and jacketed with ETFE and ECTFE resulting in excellent electrical and mechanical properties. A 24-gauge wire was insulated with an ETFE jacket and core. The jacket was solid (25 pm thick) and covered a foam insulation core (0.127 pm). This insulation had 45% void content and a dielectric breakdown voltage of 20 kV/mm. 

The simphfled structure in Fig. 11.15 shows the ratio of the monomers being 1 1 and strictly alternating, which is the desirable proportion. Commonly known by the trade name, Halar , ECTFE is an expensive, melt-processable, semicrystalhne, whitish semiopaque thermoplastic with good chemical resistance and barrier properties. It also has good tensile and creep properties and good high-frequency electrical characteristics. 

---