Guide to Fluoropolymers
PFA is the material of choice for the majority of Savillex’s products due to its superior properties. Of key importance is the purity of the material and its excellent chemical resistance, making it ideally suited for products serving the analytical, semiconductor, medical, pharmaceutical and chemical processing industries. PFA is translucent so the user can see inside the product. It has the widest service temperature range of the fluorocarbons, ranging from -328deg.F/-200deg.C to 500deg.F/260deg.C. In comparison to PTFE, PFA demonstrates greater strength, stiffness and creep resistance. In addition, it has a low coefficient of friction and beneficial anti-stick properties. PFA is considered by some to be the best melt processable fluoropolymer.
An extremely low coefficient of friction makes PTFE an excellent material where surface wear might be a problem. PTFE exhibits a useful service range from below -100deg.F/-73deg.C to temperatures of over 500deg.F/260deg.C. Its resistance to solvents is excellent throughout a wide range of temperatures. Its low dielectric constant and electric resistance also remain constant throughout this range. The major disadvantage with PTFE is the very high melt viscosity that makes processing difficult by normal extrusion and injection molding methods, and its propensity to creep and cold flow. For use in the fabrication of sample introduction products, PTFE is not ideal because the material is opaque, which does not allow the user to see inside the product. Parts are typically machined into final use products.
FEP (fluorinated ethylene propylene)
FEP has similar mechanical and chemical properties to PTFE but better impact strength and is melt processable. The material tends to be translucent in color and fairly rigid. It offers excellent chemical resistance. FEP can withstand temperatures ranging from -328deg.F/-200deg.C to 392deg.F/200deg.C and may be sterilized repeatedly.
ECTFE is translucent white and is a melt-processable alternating copolymer of ethylene and chlorotrifluoroethylene. It has excellent electrical properties and chemical resistance. ECTFE can withstand continuous exposure to extreme temperatures while maintaining its excellent mechanical properties. In addition, it is non-burning and resistant to radiation.
ETFE is a partially fluorinated copolymer that is translucent white in color and has good chemical resistance. Its mechanical properties approach that of fully fluorinated polymers but have a lower maximum service temperature. ETFE is another melt-processable fluoropolymer with greater abrasion resistance and impact strength than FEP and PTFE.
PVDF (polyvinylidene fluoride)
PVDF is a partially fluorinated homopolymer and is made by polymerizing vinylidene monomer. It is opaque in color, resists UV radiation, and offers high mechanical strength and abrasion resistance. These properties, along with its chemical resistance, make PVDF a popular choice for molded automotive, electrical and chemical piping products.
PEEK is a high temperature thermoplastic with excellent strength, creep and wear resistance properties, even at high temperatures. Though it is resistant to a wide range of organic and inorganic liquids, its chemical compatibility is not as high as PFA and other fully fluorinated polymers.