In high-performance engineering plastic selection, polytetrafluoroethylene (PTFE) and polyetheretherketone (PEEK) are frequently compared side by side. Both offer excellent chemical resistance, yet they differ significantly in mechanical strength, high-temperature load capacity, and cost. Based on standard test data, this article helps purchasers make quick decisions.
1. Material Property Comparison Table
| Parameter |
PTFE |
PEEK |
Test Standard |
| Density (g/cm³) |
2.13–2.20 |
1.30–1.32 |
ASTM D792 |
| Melting point (°C) |
327 |
343 |
ISO 11357 (DSC) |
| Glass transition Tg (°C) |
— |
143 |
ISO 11357 |
| Continuous service temp (°C) |
-200 ~ 260 |
-50 ~ 250 |
— |
| Tensile strength (MPa) |
20–35 |
90–100 |
ASTM D638 |
| Tensile modulus (GPa) |
0.5–0.7 |
3.6–4.0 |
ASTM D638 |
| Elongation at break (%) |
300–500 |
30–50 |
ASTM D638 |
| Coefficient of friction |
0.05–0.10 |
0.30–0.40 |
ASTM D1894 |
| Water absorption (%) |
<0.01 |
~0.5 |
ASTM D570 |
| Rockwell hardness |
R25–R58 |
R126 |
ASTM D785 |
| Flammability |
V-0 |
V-0 (natural) |
UL 94 |
| Dielectric constant (1MHz) |
2.1 |
3.2 |
ASTM D150 |
2. Performance Analysis
Temperature & Load: PTFE has a melting point of 327°C and short-term resistance to 260°C, but its mechanical strength drops sharply as temperature rises, and it exhibits significant cold flow (creep) even at 23°C, making it unsuitable for load-bearing structural parts. PEEK has a Tg of 143°C and melting point of 343°C, retaining about 40 MPa tensile strength at 250°C with far superior creep resistance — one of the few thermoplastics that can bear load at high temperatures.
Friction & Wear: PTFE is among the lowest-friction solids known (0.05–0.10) with excellent self-lubrication, but pure PTFE has poor wear resistance and cold-flows easily. PEEK’s friction coefficient is higher (0.30–0.40), but with carbon fiber, PTFE, or graphite fillers its wear resistance improves by an order of magnitude, making it better suited for gears, bearings, and other dynamic friction scenarios.
Chemical Resistance: Both resist most chemicals. PTFE resists nearly all chemicals (except molten alkali metals, fluorine, and some fluorides); PEEK resists acids, alkalis, oils, and most organic solvents but not concentrated sulfuric/nitric acid or halohydrocarbons. In extreme corrosive environments, PTFE remains the first choice.
Electrical Properties: PTFE’s dielectric constant of just 2.1 makes it an ideal low-loss insulator; PEEK’s 3.2 is good but with slightly higher high-frequency loss.
3. Application Scenarios
PTFE: Chemical pipe linings and seals, non-stick coatings, high-frequency cable insulation, gaskets, filled bearings (with glass fiber/bronze powder), semiconductor wet-process components. Its strengths are extreme chemical inertness, very low friction, and wide temperature range.
PEEK: Aerospace fasteners and brackets, medical implants (ISO 10993 biocompatible), semiconductor wafer carriers, automotive transmission gears and bearings, compressor valve plates, oil & gas downhole components. Its strengths are high strength, creep resistance, and repeatable steam sterilization.
4. Cost-Benefit Evaluation
PTFE raw material costs about $10–20/kg (by grade), processed mainly by molding/sintering with moderate difficulty. PEEK costs about $80–120/kg — 5–8× PTFE — and requires high-temperature injection molding (melt ~350–400°C), with higher tooling and energy costs. However, over the full lifecycle, PEEK parts often last 3–10× longer than PTFE. In applications with frequent replacement and high downtime costs, PEEK’s per-use cost is actually lower. PTFE stands out for cost-sensitive, high-volume sealing and insulation scenarios with modest strength requirements.
5. Selection Advice
- Choose PTFE when: extremely low friction/self-lubrication, extreme chemical corrosion, wide temperature range (-200~260°C), and no high mechanical load are needed — e.g., gaskets, chemical linings, cable insulation. Prioritize when budget is tight and volume is high.
- Choose PEEK when: structural load-bearing, high-temperature creep resistance, wear-resistant moving parts, medical/food-grade compliance, or repeatable sterilization are required — e.g., gears, bearings, implants, aerospace parts. Prioritize for long life and reliability over short-term cost.
- Compromise: Use filled PTFE (glass/carbon fiber) to improve wear and creep resistance, or carbon-fiber-reinforced PEEK to reduce cost sensitivity; for pure sealing at low pressure, PTFE remains the more economical choice.
Conclusion: There is no “better” material, only a “more suitable” working condition. For low-temperature, low-pressure sealing and chemical barriers, choose PTFE; for high-temperature load-bearing and structural wear resistance, choose PEEK. We recommend purchasers clarify working temperature, load, media, and compliance requirements first, then select against the table above, and obtain third-party test reports (SGS/CMA) to verify key parameters when necessary.