Materials
PEEK vs PI vs PTFE: Choosing a High-Performance Polymer
PEEK, polyimide (PI) and PTFE overlap in temperature and chemistry, but they fail in different ways. The right choice usually comes down to which single property dominates your application.
Side-by-side
Comparison
| Property | PEEK | PI (Vespel-type) | PTFE |
|---|---|---|---|
| Max service temp. | 260 °C | 300+ °C | 260 °C |
| Friction | Low | Low | Very low |
| Chemical resistance | Excellent | Good | Near-universal |
| Stiffness / strength | High | Highest | Low (cold flow) |
| Wear resistance | Excellent | Excellent | Poor |
| Relative cost | High | Very high | Medium |
Decision guide
How to decide
- Choose PEEK for a balance of strength, temperature and wear - the default for structural parts in semiconductor, medical and analytical equipment.
- Choose PI when the application runs hotter than PEEK allows and strength must be retained.
- Choose PTFE when chemical inertness or the lowest possible friction dominates, and mechanical load is light.
- Where cold flow rules out PTFE, PEEK usually takes its place.
FAQ
Frequently asked questions
PEEK and PI both wear well; PTFE does not. For sliding and bearing duty, PEEK with a bearing grade is usually the pragmatic answer.
PTFE is essentially inert against almost everything; PEEK is excellent against most chemicals but not all; PI is good but the least resistant of the three.
Polyimide is difficult to synthesise and machine, and it is usually chosen only when its temperature ceiling is genuinely required.
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