1. Material Property Comparison
In engineering-plastics procurement, polytetrafluoroethylene (PTFE) and polyetheretherketone (PEEK) form the most common “high-performance fluoropolymer vs. specialty engineering plastic” pairing. Both deliver excellent chemical resistance and high-temperature stability, yet they differ sharply in mechanical strength, friction behavior, and cost. This article uses standard test data to help buyers make a fast, confident decision.
| Property | PTFE | PEEK | Test Standard |
|---|---|---|---|
| Density | 2.14–2.20 g/cm³ | 1.30–1.32 g/cm³ | ASTM D792 |
| Melting point | 327°C | 343°C | — |
| Glass transition Tg | — | 143°C | — |
| Continuous service temp. | 260°C | 240–260°C | UL 746B |
| Tensile strength | 25–35 MPa | 90–100 MPa | ASTM D638 |
| Tensile modulus | 0.5 GPa | 3.6 GPa | ASTM D638 |
| Elongation at break | 300–400% | 40–50% | ASTM D638 |
| Coeff. of friction (dry) | 0.04–0.10 | 0.30–0.40 | ASTM D1894 |
| Dielectric constant (1 MHz) | 2.1 | 3.2 | ASTM D150 |
| Volume resistivity | >10¹⁸ Ω·cm | 10¹⁵–10¹⁶ Ω·cm | ASTM D257 |
| Limiting Oxygen Index | 95% | 35% | ASTM D2863 |
| Thermal conductivity | 0.25 W/(m·K) | 0.25 W/(m·K) | — |
2. Reading the Performance Data
Mechanical strength: PEEK’s tensile strength is about 3× that of PTFE and its modulus about 7×, making it a true load-bearing structural material. PTFE is low-strength and prone to creep, suited only to low-load seals and linings.
Friction & wear: PTFE is famous for its very low self-friction coefficient and is ideal for dry-running bearings and oil-free lubrication. However, virgin PTFE wears poorly and is usually filled with glass fiber, bronze, or carbon fiber. PEEK has a higher dry-friction coefficient, but carbon-fiber filling greatly raises its PV (pressure × velocity) limit.
Chemical resistance: Both are excellent. PTFE resists virtually all chemicals (except molten alkali metals and fluorine). PEEK resists most organics, acids, and bases, but is slightly weaker against concentrated sulfuric acid and some high-temperature halogenated solvents.
Temperature & flame: PTFE is stable long-term at 260°C with an LOI of 95% (non-combustible). PEEK’s LOI is 35% and it is UL 94 V-0 self-extinguishing.
Electrical: PTFE’s lower dielectric constant and loss make it the first choice for high-frequency and high-voltage insulation; PEEK performs well but slightly higher.
3. Application Scenarios
Typical PTFE uses: Chemical-pipe linings and valve seals, non-stick coatings, low-load oil-free bearings, high-frequency wire & cable insulation, gaskets, and expansion joints.
Typical PEEK uses: Aerospace fasteners and brackets near engines, automotive under-hood sensor housings, orthopedic implants and surgical instruments, semiconductor wafer carriers, high-PV bearing cages, and compressor valve plates.
4. Cost-Benefit Assessment
At the resin level, PTFE costs about USD 8–15/kg while PEEK runs USD 50–100/kg — PEEK is roughly 5–8× more expensive per kilogram. Yet look at total-lifecycle cost: where load-bearing, wear-resistant, or precision dimensions are required, PTFE must be thickened or replaced often, so its all-in cost may not be lower. For pure sealing, insulation, or anti-stick duty, PTFE meets the need at lower cost and higher value.
5. Selection Guidance
Choose PTFE when: ① chemical corrosion resistance is the top priority; ② you need very low friction, oil-free lubrication, or non-stick behavior; ③ the part is a low-load seal/lining/insulator; ④ budget is tight and volumes are high.
Choose PEEK when: ① high mechanical strength or stiffness is needed (load-bearing structure); ② strength and dimensional stability must hold at elevated temperature; ③ high wear resistance, high PV, and tight tolerances are required; ④ the part serves medical/aerospace with strict certification.
Conclusion
There is no “better” material, only a “more suitable” one. Frame your need with the four factors — load + temperature + media + budget — then match against the table above for a fast selection. If still undecided, request samples of both materials and run measured PV-value and creep tests.
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