In the selection of high-performance engineering plastics, polytetrafluoroethylene (PTFE) and polyetheretherketone (PEEK) are two names frequently discussed side by side. Both offer excellent chemical resistance and wide-temperature stability, yet their physical nature, mechanical behavior, and cost structures differ fundamentally. This article compares the two across material properties, performance parameters, application scenarios, and cost-effectiveness to help procurement professionals make rational decisions.
1. Material Property Comparison
| Dimension | PTFE (Polytetrafluoroethylene) | PEEK (Polyetheretherketone) |
|---|---|---|
| Chemical class | Fluorocarbon polymer | Semicrystalline aromatic polyketone |
| Appearance | Opaque, milky white | Translucent, beige/amber |
| Density (g/cm³) | 2.13–2.20 | 1.30–1.32 |
| Melting point (°C) | 327 | 343 |
| Continuous service temp (°C) | ~260 | ~240–260 |
| Coefficient of friction | 0.05–0.10 (very low) | 0.30–0.40 (needs modification) |
| Tensile strength (MPa) | 20–35 (neat) | 90–100 (neat) |
| Dielectric constant (1MHz) | ~2.1 | ~3.2 |
| Processing | Compression sintering, molding | Injection molding, extrusion |
| Relative cost index | 1.0 (baseline) | 8–15× |
2. In-Depth Performance Comparison
Chemical Resistance
Both are inert to the vast majority of acids, bases, and organic solvents. PTFE is attacked by almost nothing (except molten alkali metals, fluorine, and certain fluorinating agents at high temperature); PEEK is also excellent but degrades under hot concentrated sulfuric or nitric acid. On extreme chemical inertness, PTFE has the edge.
Mechanical Strength
This is the biggest divide. PTFE has low mechanical strength and poor creep resistance; neat resin can hardly serve as a load-bearing structural part. PEEK reaches 90–100 MPa tensile strength (neat), and over 200 MPa when reinforced with glass or carbon fiber, with strong creep and fatigue resistance—directly replacing metal in structural components.
Friction and Wear
PTFE is an exceptional self-lubricant, among the lowest-friction solids known, ideal for oil-free lubrication. PEEK has a higher friction coefficient but can be improved by filling with PTFE, graphite, or carbon fiber, and its wear resistance surpasses neat PTFE.
Temperature and Flame Retardancy
PTFE melts at 327°C with a continuous service temperature around 260°C and a limiting oxygen index (LOI) >95, inherently non-flammable. PEEK melts at 343°C, serves continuously at 240–260°C, with LOI ~35 and UL94 V-0 rating. Both suit high-temperature environments; PEEK tolerates higher short-term peaks.
Electrical Properties
PTFE’s dielectric constant is low and stable (~2.1), making it the first choice for high-frequency/RF insulation. PEEK’s is about 3.2, suitable for general electrical insulation but inferior to PTFE at high frequencies.
3. Application Scenario Analysis
Typical PTFE applications:
- Seals, gaskets, valve liners (aggressive media)
- Non-stick coatings (cookware, industrial molds)
- High-frequency coaxial cable insulation, PCB substrates
- Oil-free bearings, piston rings
- Medical tubing, vascular grafts (bio-inert)
Typical PEEK applications:
- Aerospace structural parts, engine-adjacent components
- Automotive transmission gears, bearing cages
- Medical implants (spinal fusion cages, orthopedic plates, X-ray transparent)
- Semiconductor wafer carriers
- Oil & gas downhole corrosion-resistant structures
4. Cost-Benefit Evaluation
PTFE resin is relatively inexpensive (roughly 30–60 RMB/kg by grade), with low cost per unit volume, ideal for high-volume sealing and anti-corrosion scenarios with modest mechanical demands. PEEK resin is costly (roughly 400–800 RMB/kg), requires high-temperature injection equipment, and carries high processing cost—but as a structural substitute for metal it delivers weight savings, maintenance-free operation, and long service life.
From a total-lifecycle-cost perspective: PTFE offers excellent value in static sealing and anti-corrosion linings; PEEK delivers better cost-per-function in dynamic/structural parts that must simultaneously meet high strength, temperature, chemical, and lightweight requirements.
5. Selection Recommendations
- Choose PTFE if: your core needs are extreme chemical inertness, ultra-low friction, and high-frequency insulation, with no high mechanical load. Typical: chemical seals, non-stick coatings, RF insulation.
- Choose PEEK if: your part must bear structural loads, resist temperature and chemicals, require lightweighting and long life, and budget allows. Typical: aerospace structures, medical implants, automotive drivetrain parts.
- Hybrid approach: High-end seals often use PEEK as the matrix with PTFE filler, combining strength and self-lubrication.
Conclusion
PTFE and PEEK are complementary, not substitutive. PTFE is the “king of chemistry and friction”; PEEK is the “all-rounder of strength and temperature.” Procurement teams should map requirements across four coordinates—load, temperature, chemical media, and budget—and adopt composite solutions where necessary. Before ordering, request third-party test reports (e.g., ASTM D4894, ISO 10993) and validate with small batches before scaling up.
Leave a Reply