Perfluoropolymers chemical resistance

Copolymers of ethylene with tetrafluoroethylene (ETFE) and chlorotrifluoroethylene (ECTFE) are mechanically stronger than perfluoropolymers, with some reduction in their chemical resistance and continuous use temperature and an increase in the coefficient of friction. 

Perfluoropolymers such as PTFE, PFA, and FEP are by far the most chemically resistant among thermoplastics. Few substances chemically interact with... 

Perfluoropolymers derive their chemical resistance from an extremely strong carbon-fluorine bond and an impermeable sheath of fluorine atoms surrounding the carbon-carbon chain. Relatively high crystalline content renders these polymers insoluble in solvents. 

Perfluorinated ethylene-propylene (FEP) is a copolymer of tetrafluoroethylene (TFE) and hexafluoro-propylene (HFP). It has the basic properties of poly-tetrafluoroethylene such as chemical resistance, low friction, and good electrical properties. FEP was the first tmly melt processible perfluoropolymer developed in the 1950s and commercialized in 1960. 

Carbon, fluorine, and hydrogen are the major elements that form the perfluorinated and partially fluori-nated fluoropolymers. The presence of fluorine is the main reason that these plastics have many special properties, which surpass those of most polymers. The desirable properties span across mechanical, tribological, electrical, and thermal characteristics of these polymers in addition to chemical resistance. Increased fluorine content of the fluoropolymers enhances these properties. Consequently, perfluoropolymers should be sought out when ultimate chemical resistance, electrical properties, etc., are required. This chapter concentrates on presenting the key properties of fluoropolymers. Properties of fluoroplastics films can be found in Ch. 6 and Appendix VI. 

As in the case of ETFE, ECTFE terpolymers (same termonomers) have better mechanical, abrasion, and radiation resistance than those of PTFE and other perfluoropolymers. Dielectric constant of ECTFE is 2.5-2.6, and it is independent of temperature and frequency. Dissipation factor is 0.02 and much larger than ETFE s. ECTFE is resistant to most chemicals except for hot polar and chlorinated solvents. It does... 

Huorinated polymers have quite different properties compared to their hydrocarbon counterparts, due to the nature of the C-F bond. They often have a particularly high thermal and chemical stability, insolubility in common organic solvents and resistance to swelling by condensable gases or vapours. Such properties are an advantage for those membrane applications where the separation takes place under harsh conditions. Crystalline perfluoropolymers such as Teflon are extremely stable but their crystalline nature makes them mostly suitable for porous membranes, either for filtration of liquid media, or for instance for membrane distillation processes which take advantage of the... 

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