FEP (/11)
FEP
You may not recognize the name fluorinated ethylene propylene (FEP), but it was also originally marketed as Teflon® because of similarities in the material. The main difference is that although it's also considered high temperature, FEP has a lower operating temperature range, -88°F to 392°F (-67°C to 200°C), stopping below PTFE's 644°F (340°C). Consequently, FEP is not used in cookware or utensils.
It can be used for things like coating surgical instruments, jacketing guidewires, abrasion and corrosion protection, and so on. It shrinks at 212°F (100°C), which is again much lower than PTFE's minimum of 617°F (325°C). It's available in 1.3:1 and 1.6:1 shrink ratios, but can also shrink up to 15% in length.
A: Teflon® is just a brand name that's been used for both, but chemically they are slightly different. PTFE comprises a chain of molecules with four fluorine atoms and two carbon atoms. FEP has this same molecule but it alternates with a molecule containing six fluorine atoms and three carbon atoms, which is what gives them different properties.
A: They are similar elements and in the same grouping in the periodic table, known as Halogens. Fluorine is the lightest and chlorine is next up in mass, and both are gases on their own and would be dangerous. However, fluorine in particular bonds very tightly with other molecules such as carbon, so once it's been put into a material it's most likely not coming out.
