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These polymers are essentially those in which some or all of the
hydrogen atoms in polyethylene have been replaced by fluorine, with
polytetrafluoroethylene (PTFE) perhaps the best known. PTFE is a tough,
flexible, crystalline polymer that retains ductility down to -150°C.
Its solvent and chemical resistance is the best of all the
thermoplastics and it has the lowest coefficient of friction of any
known solid (0.02). On the downside, it has to be moulded by a powder
sintering technique, although it can be extruded very slowly, and it is
very expensive with low strength and stiffness. Applications of PTFE
are therefore limited to those that make use of its special properties,
for example, bearings, chemical vessel linings, gaskets and non-stick
coatings. Other fluoropolymers include: polyvinyl fluoride (PVF),
polyvinylidene fluoride (PVDF), perfluoroalkoxy tetrafluoroethylene (PFA)
and polychloro trifluoroethylene (PCTFE).
These are largely the results of attempts to derive polymers with all
the benefits of PTFE that are melt processable. These attempts have met
with some success, although none of the melt processable fluoropolymers
can match the chemical inertness of PTFE. PVDF has useful piezoelectric
properties.
 Teflon
Material
Notes
This is the brand name for a number of fluorinated polymers. Teflon is
polytetrafluroethylene (PTFE). This is a polymer with repeating chains
of –(CF2-CF2)- in it.
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