Take a trip down the street and ask someone if they know what fluoropolymers are. Ignore the look they give you and then ask again if they now what Teflon is. You’ll most probably get an answer this time.
Teflon is renowned for being used in frying pans to give them the ‘non-stick’ character. But most people are unaware that it is a fluoropolymer. There are other fluoropolymers widely used in various industries.
The two most common fluoropolymers are Perfluoroalkoxy (PFA) and polytetrafluoroethylene (PTFE). The same class of polymers, they have a number of similar properties. However, there are a few differences too.
These differences are the deciding factor of what material is used for which application.
Physical and chemical properties
One of the major differences between these two types of Teflon materials is that PFA is melt processable while PTFE isn’t. This is done through either screw extrusion techniques or conventional injection molding.
On the other hand, PTFE has a high molecular weight and is comprised mainly of carbon and fluorine. As a fluorocarbon solid, PTFE is hydrophobic and thus can get wet if exposed to water or water containing substances. It also has a low coefficient of friction and high electronegativity.
PFA is often used for laboratory equipment because of its resistance to most chemicals. It also has a high optical transparency and flexibility making it suitable for laboratory plastic.
PFA tubing is also used for handling critical or corrosive processes. These are also used as sheet linings for chemical equipment.
PTFE is the popular non-stick covering of frying pans and other kitchen ware. It is also used in pipes and containers for handling corrosive and reactive materials. It is sometimes used as a lubricant to reduce friction in machinery, minimize friction-related damage and improve energy consumption.
Flexibility, resistance and electrical properties
PFA is more flexible than PTFE tubing; however, it has lower flex life (ability to endure repetitive folding) than PTFE.
PTFE is a bit more resistant to heat. It is also less affected by water absorption and weathering. However, PFA is more resistant to salt spray. While both PFA and PTFE have almost the same dielectric constant and dissipation factor, the dielectric strength of PFA is almost four times higher than PTFE.