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PFA

PFA is short for perfluoroalkoxy, or better known by DuPont’s brand name, Teflon® PFA. PFA has outstanding non-stick properties by having a low friction coefficient. It is a fairly flexible polymer with a high resistance to stress cracking and is resistant to almost all solvents and chemicals. PFA is also capable of withstanding both high and low-temperature conditions. It is able to provide continuous service temperatures up to 260°C (500°F). PFA offers extraordinary flame resistance, chemical stability, and high dielectric strength.

A wide variety of applications involving critical, highly corrosive processes use PFA tubing. PFA lining material can protect chemical equipment from corrosion. Additional applications can include filtration housings, heat exchangers, pump housings, fittings, etc. Process Technology utilizes PFA in the construction of TIH inline chemical heaters, Pulsar point-of-use (POU) inline heater, XC Series inline exchanger, and X Series immersion coils.

PTFE

PTFE (polytetrafluoroethylene) is the most popular form of Teflon and is also a synthetic fluoropolymer of tetrafluoroethylene. Additional names for PTFE are Fluon and Syncolon. In 1938, PTFE was accidentally discovered by Roy Plunkett of the DuPont Company while attempting to create a non-flammable and non-toxic coolant for refrigerators. It is a high-molecular-weight compound consisting of carbon and fluorine, a fluorocarbon solid. PTFE is hydrophobic – no, it’s not afraid of water – it doesn’t get wet from water or any substances containing water. The high electronegativity of fluorine provides PTFE with a very low friction coefficient when it comes into contact with solids giving PTFE its well-known “slipperiness” property. Other characteristics of PTFE include high chemical resistance, low- & high-temperature capabilities, resistance to weathering, as well as electrical & thermal insulation.

PTFE has many applications such as a non-stick coating for pans and cookware. Its non-reactive properties make it ideal for lining pipes, containers, and tanks that contain corrosive and reactive chemicals. An exceptional lubricant, PTFE can improve energy consumption and less wear & tear when used in machinery as it reduces friction. Process Technology utilizes PTFE in the construction of the TIH, and SHC inline chemical heaters, as well as the Lufran ultra-pure water heater, HX Series immersion heaters, X Series immersion coils, and LTFH high-temperature filter housing.

The Difference

There are a few significant property differences between these two fluoropolymers to consider when choosing the right one for your process. Differences in alkoxy substituents allow PFA to be melt processable through conventional injection molding and screw extrusion techniques, whereas PTFE is not. PFA is more flexible but has a lower flex-life, so it isn’t as capable of enduring repetitive folding. PTFE has a slightly higher heat resistance but lacks when compared with the flow, creep resistance, and thermal stability. The melting points of PFA and PTFE are 260°C and 327°C respectively. Water absorption and weathering affect PFA more than PTFE, although PFA is superior in salt spray resistance. Finally, the most notable difference between the two is that PFA’s dielectric strength is 3 to 4 times higher than PTFE.

We hope that this has left you with a better understanding of these fluoropolymers!

 Shared January 5th, 2018

By Kevin Harrison, Process Technolog