PTFE has a particular chemical composition of polymers which contain only carbon and fluorine atoms. This gives it a particularly remarkable set of chemical, physical and dielectric properties which place the PTFE among the thermoplastics although it does not melt. PTFE is very resistant to virtually all chemicals. This property is due on the one hand to the strength of the CF bond (484 kJ / mol compared to 412 kJ / mol of the CH bond) and on the other hand to the fact that the polyethylene chain is "embedded" in a matrix d 'fluorine atoms that protects it. For example, the PFA, immersed for seven days in aqua regia at 120 ° C., undergoes a modification of its physical properties (traction, elongation) of the order of only 1%.
It can undergo high operating temperatures. They range from 155 ° C for Tefzel to 260 ° C for PTFE for permanent use and can be increased for shorter use. These products only begin to degrade at around 400-500 ° C.
Due to its properties PTFE finds many applications, both in industry and for domestic jobs:
Mechanical, automotive, aviation: it is used to manufacture mechanisms that do not need to be lubricated as well as joints. It is involved in the isolation of power steering accessories, automatic transmissions and shock absorbers, in brake control cables. It is also used in the manufacture of kerosene and lubricant resistant seals, pressure piping and engine parts. A European automobile of average type contains about 100 g.
Industry, construction and electricity : it is found in the lining of pipes, in pumps for the chemical, pharmaceutical and food industries in the coating of woven glass fibers in insulation for cables and wires.
Protection of the environment : it can be found in recycling processes (desulphurisation of gases from thermal power plants, dust filters in industrial processes, etc.).
Medicine : it is found in implants (artificial ligaments, artificial hearts and burn care) as well as in various utensils (catheters, capillary tubes, hypodermic syringes).
Sport and leisure : it is used in textile membranes intended for clothing, as a component in ski bindings. We find about 20 g in an anorak. The Gore-Tex® fabric is obtained by gluing a textile on a foamed membrane and has protection against the weather while letting escape the water vapor emitted by the body.