Fluoropolymer
A fluoropolymer is a fluorocarbon-based polymer with multiple carbon–fluorine bonds. It is characterized by a high resistance to solvents, acids, and bases. The best known fluoropolymer is polytetrafluoroethylene under the brand name "Teflon," trademarked by the DuPont Company.
History
In 1938, polytetrafluoroethylene was discovered by accident by a recently hired DuPont Ph.D., Roy J. Plunkett. While working with tetrafluoroethylene gas to develop refrigerants, he noticed that a previously pressurized cylinder had no pressure remaining. In dissecting the cylinder, he found a mass of white solid in a quantity similar to that of the tetrafluoroethylene gas. It was determined that this material was a new-to-the-world polymer. Tests showed the substance was resistant to corrosion from most acids, bases and solvents and had better high temperature stability than any other plastic. By early 1941, a crash program was making substantial quantities of PTFE for the Manhattan Project.Properties
Fluoropolymers share the properties of fluorocarbons in that they are not as susceptible to the van der Waals force as hydrocarbons. This contributes to their non-stick and friction reducing properties. Also, they are stable due to the stability multiple carbon–fluorine bonds add to a chemical compound. Fluoropolymers may be mechanically characterized as thermosets or thermoplastics. Fluoropolymers can be homopolymers or copolymers.Examples of monomers used to prepare fluoropolymers
- Perfluorocycloalkene
- Ethylene
- Vinyl fluoride
- Vinylidene fluoride
- Tetrafluoroethylene
- Chlorotrifluoroethylene
- Propylene
- Hexafluoropropylene
- Perfluoropropylvinylether
- Perfluoro
Examples of fluoropolymers
Typical properties
| Property | Method No. | Units | PTFE | FEP | PFA | ETFE | ECTFE | PCTFE | PVDF |
| Specific gravity | D792 | - | 2.17 | 2.15 | 2.15 | 1.7 | 1.7 | 2.15 | 1.78 |
| Yield strength | D638 | MPa | 10 | 12 | 15.5 | 24 | 31 | 40 | 46 |
| Yield strength | D638 | PSI | 1,450 | 1,740 | 2,250 | 3,480 | 4,500 | 5,800 | 6,670 |
| Elongation | % | 200-500 | 250-350 | 300 | 200-500 | 200-300 | 80-250 | 20-150 | |
| Tensile modulus | D638 | MPa | 600 | 500 | 700 | 1500 | 1655 | 1500 | 2400 |
| Tensile modulus | D638 | ksi | 87 | 72.5 | 101.5 | 217.5 | 240 | 218 | 348 |
| Hardness | D2240 | Shore D | 60 | 57 | 62 | 75 | 75 | 90 | 79 |
| HDT, @ 66 PSI | D648 | °F | 250 | 158 | 164 | 219 | 240 | 248 | 300 |
| HDT, @ 264 PSI | D648 | °F | 122 | 129 | 118 | 160 | 169 | - | 239 |
| Limiting oxygen index | D2863 | % | >95 | >95 | >95 | 30-36 | |||
| Dielectric constant | D150 | 1 MHz | 2.1 | 2.1 | 2.1 | 2.6 |