Expanded PTFE (ePTFE) gaskets are composed of a synthetic fluoropolymer derived from polytetrafluoroethylene (PTFE), consisting solely of carbon and fluorine atoms. This unique molecular structure gives them exceptional properties like chemical inertness, temperature resistance (-200°C to +260°C), and hydrophobicity. The material is mechanically stretched during manufacturing to create a microporous structure, enhancing flexibility and compressibility while maintaining PTFE's inherent benefits. These gaskets excel in sealing applications due to their low friction, electrical insulation, and resistance to creep relaxation, making them ideal for demanding industrial environments.
Key Points Explained:
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Base Material Composition
- Expanded expanded ptfe gasket are made from PTFE (polytetrafluoroethylene), a synthetic fluoropolymer consisting exclusively of carbon (C) and fluorine (F) atoms arranged in a linear molecular chain.
- The chemical formula is (CF₂-CF₂)ₙ, forming a highly stable structure resistant to bond breaking under stress or heat.
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Manufacturing Process
- PTFE is mechanically stretched to create a microporous matrix, transforming it into ePTFE. This expansion:
- Increases surface area for better sealing
- Enhances compressibility (up to 40% deformation rate)
- Maintains the base material’s chemical resistance
- PTFE is mechanically stretched to create a microporous matrix, transforming it into ePTFE. This expansion:
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Key Properties from Composition
- Hydrophobicity: The fluorine-carbon bonds repel water and water-based fluids.
- Thermal Stability: Withstands -200°C to +260°C due to strong C-F bonds (457 kJ/mol dissociation energy).
- Chemical Inertness: Resists virtually all industrial chemicals except molten alkali metals and fluorine gas.
- Low Friction: Coefficient of 0.05–0.10, reducing wear in dynamic applications.
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Performance Advantages
- Sealing Efficiency: Microporous structure adapts to flange irregularities better than solid PTFE.
- Electrical Insulation: Dielectric strength of 60–100 kV/mm (virgin PTFE).
- Non-Aging: No plasticizers to leach out, ensuring stable performance over decades.
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Industry Applications
- Chemical processing (pumps, reactors)
- Semiconductor manufacturing (ultra-pure fluid handling)
- Energy (flange seals in oil/gas pipelines)
The combination of PTFE’s atomic structure and the expansion process creates a material that outperforms conventional gaskets in extreme environments while remaining compliant enough for delicate sealing tasks.
Summary Table:
| Property | Value/Characteristic |
|---|---|
| Base Material | PTFE (Polytetrafluoroethylene) |
| Chemical Formula | (CF₂-CF₂)ₙ |
| Temperature Range | -200°C to +260°C |
| Compressibility | Up to 40% deformation rate |
| Hydrophobicity | Repels water and water-based fluids |
| Dielectric Strength | 60–100 kV/mm (virgin PTFE) |
| Key Industries Served | Chemical, Semiconductor, Energy |
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