PTFE
Polytetrafluoroethylene
(PTFE) resin is in a class of paraffinic polymers that have
some or all of the hydrogen replaced by fluoride. The original PTFE
resin was invented by DuPont in 1938 and called Teflon®.
PTFE is a completely fluorinated polymer manufactured by free
radical polymerization of tetrafluoroethylene. With a linear molecular structure
of repeating –CF-CF2-units, PTFE is a crystalline polymer with a melting
point of about 621F (327C). Density is 2.13 to 2.19 g. PTFE
has exceptional resistance to chemicals. Its dielectric constant (2.1) and loss
factor are low and stable across wide temperature and frequency range. PTFE
has useful mechanical properties from cryogenic temperatures at 500oF (280oC)
continuous service temperatures. Its coefficient of friction is lower than almost
any other material. It also has a high oxygen level.
Filled PTFE
PTFE reinforced with various fillers suited for more severe applications. The fillers such as Barium Sulfite, Silica or Glass Spheres give varying enhanced properties Over conventional PTFE gasketing properties. Increased resistance to cold flow, strength & chemical resistance. Trademarks such as Gylon, Sigma, Flurogreen are some of the most popular Filled PTFE products.
| Properties | ATM Method | Units | Virgin PTFE | Reprocessed PTFE | 25% Glass PTFE |
| Specific Gravity | D792 | 2.14-2.20 | 2.15-2.20 | 220-230 | |
| Tensile Strength | D638 | PSI | 1500-3500 | 1500-2400 | 2000-3000 |
| Elongation | D638 | % | 250-350 | 75-200 | 100-260 |
| Hardness | D1700 | Durometer "D" | 50-60 | 55-65 | |
| Deformation %730°F, 1500 psi, 24 hours | D621 | 4-8 | 1.73 | ||
| Deformation %1000°F, 1500 psi, 24 hours | D621 | 10-18 | 1.91 | ||
| Deformation %2000°F, 1500 psi, 24 hours | D621 | 20-25 | 4.57 | ||
| Impact Strength,Izod7300°F Average1700F Average | D256 | Ft./Lb./In. | 3.00 6.00 | 2.543.69 | |
| Water Absorption | D570 | % | 0.001 | 0.013 | |
| Coefficient of Friction(Static) 730°F | *3 | 0.04 | 0.013 | ||
| Dielectric Constant(100 CPS) | D150 | 2.00 | 2.26 | 2.4 | |
| Dielectric Strength (4) (air) | D257 | Volts | 1000 | 450 | 235 |
| Coefficient of Thermal Expansion 730°F | D696 | In./In./Ft. | 5.5 x 10.3 | 2.75 x 10.3 | |
| Coefficient of Thermal Conductivity | *5 | Btu/hr/ftz | 1.7 | 3.12 | |
| PV at 900 ft./min | 2500 | 15,000 | |||
| Color | *6 | white | off white | brownish white |
