PFA resins such as Dupont PFA are relatively newer fluorocarbon resin products. It is especially important for designers and end-users requiring release (non stick) performance or chemical stability.

Tensile strength, stiffness, and flexural modulus are outstanding. Both at cryogenic and higher continuous temperatures (500 F). With a lower molecular weight than PTFE, it is not intended for low friction.

PFA is defined as a ‘perfluorocarbon’ compound. This is a type of fluoropolymer in which the hydrogen directly attached to the carbon atoms is replaced by fluorine. The result is protection from chemical corrosion not unlike fully fluorinated polymers. Chemical resistance is outstanding.

For example, PFA plastic is chemically inert to strong mineral acids, inorganic bases, inorganic oxidizers, or salt solutions. Its resistance to organic compounds includes acids, anhydrides, aromatics, aliphatic hydrocarbons, alcohols, aldehydes, ketones, ethers, esters, chlorocarbons, fluorocarbons, and mixtures of these compounds. Though halogen products containing fluorine, for example, will attack.

So, why the advantage in PFA coating corrosion protection? Besides high permeation strength, thickness is key. With the ability to reach 0.010 inch or more, chemical penetration can be significantly retarded, thus reducing the likelihood of reaching the corrosion vulnerable substrate.

What about non-stick performance? Besides low surface energy (non wetting) look again to permeation strength. This becomes more evident in sticky applications involving compounds with sublimation byproducts (solids converted to vapors).

Keep in mind higher temperatures increased rates of permeability. It’s the fall in specific gravity, the result of more spacing between molecules and more molecular activity, that causes the easier pathway for diffusion.

PFA resins are in a class known as melt-processable fluoroplastics. PFA is similar to PTFE and FEP, although it has somewhat better mechanical properties than FEP at temperatures above 302 degrees Fahrenheit, and can be used to 500 degrees Fahrenheit. It is about equal to PTFE in chemical resistance.