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Permeability
editYes, it ECTFE has low permeability for a fluoropolymer, but "the best"? Better than PVF? From "Permeability Properties of Plastics and Elastomers" and manufacturer datasheets for the two products we see the following:
cm³-mm/m²-day-atm H2: PVF = 22.9@24°C, ECTFE = 108@25°C He: PVF = 59.1@24°C, ECTFE = 1798@25°C CO2: PVF = 4,4@24°C, ECTFE = 90@15°C N2: PVF = 0.1@24°C, ECTFE = 1.23@25°C or 10.0@25°C (sources vary) O2: PVF = 1.3@24°C, ECTFE = 9,9@25°C or 45.6°25°C (sources vary)
Water permeability seems to be about the same, though. But in general, PVF is about on par with PET. ECTFE... isn't. Even though it's orders of magnitude better than, say, PTFE.
Also... the article claims that ECTFE's permeability properties are a consequence of the size of the chlorine atom. Is that... actually the case? -- Rei (talk) 03:54, 17 July 2016 (UTC)