Material Guide
PTFE (Teflon) Properties
PTFE has the widest chemical resistance and temperature range of any common polymer. Learn its properties, applications in seals and gaskets, and limitations.
5 min readUpdated July 2026
Overview
PTFE (Polytetrafluoroethylene), commonly known as Teflon, is a fluoropolymer with extraordinary chemical resistance and the lowest coefficient of friction of any solid material. It is used extensively in seals, gaskets, valve seats, and non-stick coatings.
Key Properties
| Property | Value |
|---|---|
| Density | 2200 kg/m³ |
| Max service temperature | 260°C |
| Min service temperature | -200°C |
| Coefficient of friction | 0.05–0.10 (lowest of any solid) |
| Thermal conductivity | 0.25 W/m·K (very low) |
| Tensile strength | 20–35 MPa |
Advantages
- Exceptional chemical resistance: Resists virtually all chemicals — only molten alkali metals and elemental fluorine attack it.
- Wide temperature range: -200 to 260°C — the widest range of any common polymer.
- Lowest friction of any solid: Nothing sticks to PTFE — used for non-stick coatings and low-friction bearings.
- Non-toxic and food-safe: Inert and non-toxic — approved for food contact and medical applications.
- Excellent electrical insulator: High dielectric strength — used in wire and cable insulation.
Limitations
- Cold flow (creep): PTFE deforms under continuous load — it 'cold flows' and loses preload. Use filled grades (glass, carbon, bronze) for structural applications.
- Low strength: Tensile strength of 20–35 MPa is very low — not a structural material.
- Poor thermal conductivity: 0.25 W/m·K — acts as a thermal insulator, not suitable where heat transfer is needed.
- Difficult to bond: Nothing sticks to PTFE — surfaces must be chemically etched before bonding.
- High thermal expansion: Expands significantly with temperature — gasket design must accommodate this.
Common Filled Grades
| Filler | Benefit | Application |
|---|---|---|
| Glass fibre | Increases strength, reduces creep | Seals, gaskets, bearings |
| Carbon | Increases conductivity and wear resistance | Bearings, piston rings |
| Bronze | High wear resistance, conducts heat | Heavy-duty bearings |
| Graphite | Self-lubricating, reduces friction | Dynamic seals |
Typical Applications
- Valve seats and seals (ball, plug, needle valves)
- Gaskets (envelope and full-face)
- O-rings and chevron seals
- Pipe linings for chemical service
- Non-stick coatings (cookware, molds)
- Electrical insulation (wire, cable)
- Expanded PTFE tape (thread seal)
Chemical Compatibility
| Chemical | Rating |
|---|---|
| Acids (all concentrations) | Excellent |
| Alkalis | Excellent |
| Solvents (organic) | Excellent |
| Oxidising agents | Excellent |
| Molten alkali metals | Poor |
| Elemental fluorine | Poor |
| Steam | Good (up to 260°C) |
How CHI can help
Ask CHI about PTFE properties and to recommend filled grades for structural sealing applications. The CHI assistant can recommend the right material for your specific application, explain chemical compatibility, and flag when a material is unsuitable for your operating temperature or environment.