PTFE is the most heat stable techno-polymer: the maximum temperature of use for short periods is approximately 300 0C, and 250 0C for long periods.
It has a low solidity and resistance, whilst its extension at breaking point exceeds 100%. Shrinkage following processing is high.
Its advantages consist in its huge temperature range of use, universal chemical stability, insolubility in all known solvents at temperatures below 300 0C, resistance to atmospheric agents, excellent electrical and dielectric properties and its excellent non-stick and sliding behaviour with all materials.
Over the past 60 years, the industry has commercialized seven additional fluoroplastics: FEP, PVDF, PFA, ETFE, PCTFE, ECTFE and PVF.
PVF (polyvinyl fluoride) has outstanding resistance to weathering and good resistance to abrasion and staining. It is used as a surfacing film for industrial, architectural and decorative building materials.
PTFE (molded) is not able to be melt processed. The resin must be compressed, then sintered (a controlled heat treatment) to produce useful plastic.
FEP (fluorinated ethylene propylene) processes by conventional means. It is extruded and injection molded. It has the chemical resistance, mechanical and electrical properties of PTFE but a more narrow temperature range - maximum temperature is 400°F. Commonly used to make chemical resistant tanks and vessels for the corrosive chemical industry.
PVDF (poly-vinylidene fluoride) is not a processable fluoropolymer capable of being injection and compression molded and screw extruded. It is stiffer and resists cold flow better than PTFE, FEP, and PFA. It has a lower useful temperature range (-80 to +300°F). Glass backed sheets of PVDF make liners for vessels as does FEP. Pipe and fittings of PVDF are one of the most economical and chemical resistant, high temperature solid pipe systems available.
PFA (polyfluoroalkoxy) is also melt processable. Its properties are those of PTFE and include resistance to practically all chemicals, the useful temperature range of PTFE, resistance to weathering, low friction coefficient and excellent electrical insulation characteristics. It is however, more expensive than PTFE and FEP resins.
ETFE (ethylene tetra fluoro ethylene) is a copolymer of ethylene and tetrafluoroethylene and is readily processed by conventional methods. It has maximum service temperature of 300°F but greater strength and stiffness than PTFE, FEP and PFA. ETFE also has excellent impact strength.
PCTFE (polychlorotrifluoroethylene) is melt processible. Within its service temperature range, it has greater tensile and compressive strength than PCTFE, FEP, or PFA. At high temperatures it is subject to stress cracking. It does not have the solvent resistance of PTFE, FEP, PFA or ETFE. However, its radiation resistance is better than any of these others.
ECTFE (ethylene-chlorotrifluoroethylene) is a copolymer of ethylene and PCTFE. It is melt processible. It has excellent electrical insulating properties. At ambient temperatures its mechanical properties compare to those of nylon 6. It has excellent impact resistance at ambient and sub ambient temperatures. Its service range is -80 to +300°F.
Dielectric Properties, High Surface and Volume, Resistivity, Corrosion Resistant, Nonflammable, High Heat Resistance, Chemically Inert, Weather Resistant, Low Friction