General Properties
Short Name:
Name:
PTFE
Polytetrafluoroethylene
Polytetrafluoroethylene (PTFE) is the most widespread and important fluoropolymer. It is a linear, semi-crystalline thermoplastic showing several transitions between 0°C and 340°C. Due to its abrasion resistance and high chemical resistance, PTFE is used often in tribological systems. PTFE is also used as a coating in frying pans in many households.
Structural Formula
Properties
| Glass Transition Temperature | 120 to 130°C |
|---|---|
| Melting Temperature | 325 to 335°C |
| Melting Enthalpy | 82 J/g |
| Decomposition Temperature | 575 to 590°C |
| Young's Modulus | 400 to 750 MPa |
| Coefficient of Linear Thermal Expansion | 100 to 150 *10-6/K |
| Specific Heat Capacity | 1.0 J/(g*K) |
| Thermal Conductivity | 0.23 to 0.25 W/(m*K) |
| Density | 2.13 to 2.23 g/cm³ |
| Morphology | Semi-crystalline thermoplastic |
| General properties | Good thermal and oxidative stability. High toughness. Very good chemical resistance. Good electrical insulation. Low friction coefficient. High UV resistance |
| Processing | Special techniques for extrusion, compression/sintering for molding, films, components |
| Applications | Chemical plant construction. Food and pharma technology. Medical engineering. Nonstick coating. Sealing technology. High-frequency technology |
NETZSCH Measurement
| Instrument | DSC 204 F1 Phoenix® |
| Sample Mass | 12.80 mg |
| Isothermal Phase | 20 min |
| Heating/Colling Rates | 10 K/min |
| Crucible | Al, pierced lid |
| Atmosphere | N2 (40 ml/min) |
Evaluation
The DSC curve of the PTFE sample exhibits two overlapping peaks around 20°C. The peaks were sharper in the 2nd heating (red) than they were in the 1st heating (blue) with peak temperatures of 23°C and 32°C. A very weak glass transition at approx. 130°C was detected in the 2nd heating. The melting transitions peaked at 334°C in both heatings. The melting enthalpy with 65 J/g in the 2nd heating (red) is approx. 11% below the melting enthalpy in the 1st heating. This indicates a lower crystallinity in the 2nd heating and is consistent with the somewhat clearer glass transition step, which indicates an increase in amorphous content.