Properties
Useful comparison tables of PTFE against FEP, PFA and ETFE can be found on DuPonts website, listing the mechanical, thermal, chemical, electrical and vapour properties of each, side by side.
In terms of corrosion resistance, FEP is the only other readily available fluoropolymer that can match PTFE's own resistance to caustic agents, as it is a pure carbon-fluorine structure and fully fluorinated.
Thermally, FEP stands out from PTFE and PFA by having a melting point of 260 °C (500 °F), around forty degrees lower than PFA and lower again than PTFE.
Electrically, PTFE, FEP and PFA have identical dielectric constants, but FEP's dielectric strength is only surpassed by PFA. However, while PFA has a similar dissipation factor to PTFE, FEP's dissipation is around six times that of PFA and EFTE (making it a more non-linear conductor of electrostatic fields).
Mechanically, FEP is slightly more flexible than PTFE. Perhaps surprisingly, it does not withstand repetitive folding as well as PTFE. It also features a poorer co-efficient of dynamic friction, is softer and has a slightly lower tensile strength than PTFE and FAP.
A noteworthy property of FEP is that it is vastly superior to PTFE in some coating applications involving exposure to detergents.
ETFE, in many ways, can be thought of as belonging to a different group, as it is essentially a high strength engineering version of the others featuring what are likely to be considered slightly diminished properties in the other fields when compared with PTFE, FEP and PFA.
Read more about this topic: Fluorinated Ethylene Propylene
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