PEEK Polymer: Properties, Uses & Cost Guide
Tensile data verified against MatWeb.com database & manufacturer datasheets · Last updated July 2026
Published: 2026-05-25
Polyetheretherketone (PEEK) is a colorless organic thermoplastic polymer in the polyaryletherketone (PAEK) family, offering an exceptional combination of thermal stability, chemical resistance, and mechanical strength. It is one of the...
Polyetheretherketone (PEEK) is a colorless organic thermoplastic polymer in the polyaryletherketone (PAEK) family, offering an exceptional combination of thermal stability, chemical resistance, and mechanical strength. It is one of the highest-performing engineering thermoplastics and is used in demanding environments like aerospace components, medical implants, semiconductor manufacturing, and oil & gas downhole connectors.
PEEK can be processed by injection molding at melt temperatures of 360-400°C with mold temperatures of 160-200°C. Its semicrystalline nature requires proper mold temperature control to achieve optimal crystallinity and dimensional stability. It has excellent resistance to hydrolysis, steam, and a wide range of chemicals including acids, bases, and organic solvents—outperforming most other thermoplastics in aggressive chemical environments.
Key grades include unfilled PEEK (general purpose), 30% glass-fiber reinforced (increased stiffness and HDT), 30% carbon-fiber reinforced (maximum strength and thermal conductivity), and bearing-grade with PTFE/graphite additives for tribological applications.
Recommended Applications
PEEK Polyetheretherketone is commonly specified for:
⚠ Not Recommended For
PEEK Polyetheretherketone is not recommended for:
- Food contact without FDA-grade certification (Classix or 450G compliant grades only)
- Outdoor UV exposure without UV-stabilized grade (unfilled PEEK yellows and embrittles under UV)
- High-impact shock loading below -60°C (becomes brittle; consider PAI or PI instead)
Selection & Application Guide
PEEK is the material of choice when your application demands continuous service above 250°C, outstanding chemical resistance across a wide pH range, and high mechanical strength simultaneously. Choose PEEK over PTFE when load-bearing capacity matters, over Ultem when temperatures exceed 180°C, and over PPS when toughness and elongation are critical. PEEK justifies its premium cost ($80-200/kg) in aerospace, oil & gas downhole, and medical implant applications where failure is not an option.
Real-World Applications
PEEK's radiolucency (invisible on X-ray/CT) combined with bone-matching modulus makes it the standard for interbody spinal fusion devices per ASTM F2026.
PEEK withstands H2S, amine inhibitors, and 200°C+ temperatures at depth — replacing metal components that corrode in aggressive well environments.
PEEK's low particle generation, chemical resistance to strong acids, and dimensional stability at elevated temperatures make it ideal for cleanroom wafer handling.
Carbon-fiber reinforced PEEK (CA30) provides wear resistance and thermal stability for high-temperature dynamic sealing in automotive transmissions.
Processing & Cost Considerations
Manufacturing Tips
- Melt temperature must be 380-400°C with mold temperature 160-200°C — standard injection molding machines cannot process PEEK. You need a high-temperature package with ceramic heater bands and oil-heated mold system.
- Drying is critical: PEEK is hygroscopic and must be dried at 150-160°C for 3-4 hours to reach moisture content below 0.02%. Processing wet PEEK causes hydrolysis, brown discoloration, and loss of mechanical properties.
- Mold temperature controls crystallinity: below 150°C produces amorphous parts (transparent amber, lower strength); 160-180°C yields optimal semi-crystalline structure (30-35% crystallinity, opaque tan).
PEEK raw material costs $80-200/kg depending on grade (unfilled 450G is $150-200/kg, CF-reinforced $180-250/kg). Machine premium adds 30-50% for high-temperature capability. Oil-heated mold systems cost $20,000-50,000 additional. Total molded part cost runs 5-10x higher than nylon or polycarbonate. Optimize by minimizing wall thickness to reduce material usage, using unfilled grade when reinforcement isn't needed, and considering PPS as a lower-cost alternative when service temperature stays below 200°C.
Technical Properties
| Density | 1.32 g/cm³ |
|---|---|
| Tensile Strength | 100 MPa |
| Melting Point | 343 °C |
| Shrinkage Rate | 1.2% |
| Flexural Modulus | 4.1 GPa |
| Hdt | 160 °C at 1.82 MPa |
| Continuous Service Temp | 260 °C |
| Tensile Modulus | 3.6 GPa |
| Yield Strength | 100 MPa |
| Elongation At Break | 20% |
Engineering Tool: Shrinkage & Cost Estimator
Calculate part weight, mold cavity dimensions accounting for shrinkage, and material cost — all locally in your browser.
Equivalents & Cross-References
| Equivalent / Alternate | Action |
|---|---|
| Victrex PEEK | |
| Tecapeek | |
| KetaSpire | |
| Vestakeep |
Frequently Asked Questions
What melt temperature is required for injection molding PEEK?
PEEK requires a melt temperature of 360-400°C and mold temperature of 160-200°C. Standard injection molding machines cannot process PEEK—the machine must be equipped with high-temperature barrels, ceramic heater bands, and oil-heated molds. Most general-purpose machines are limited to ~350°C and are unsuitable for PEEK processing.
How does PEEK compare to PTFE (Teflon) for chemical resistance?
PEEK offers comparable chemical resistance to PTFE against most chemicals, but with vastly superior mechanical properties—PEEK's tensile strength (100 MPa) is approximately 5× higher than PTFE (20-30 MPa). PTFE has a higher continuous service temperature (260°C vs PEEK at 260°C—equivalent) and a lower coefficient of friction. Choose PTFE for unloaded seals and gaskets; choose PEEK for structural components requiring both chemical resistance and mechanical load-bearing capacity.
Can PEEK be used for FDA-compliant food contact applications?
Yes. Unfilled PEEK complies with FDA 21 CFR 177.2415 for repeated food contact. It also meets USP Class VI and ISO 10993 biocompatibility standards for medical devices. Always verify the specific grade with the manufacturer — colorants and fillers may affect compliance.
Is PEEK resistant to steam autoclaving?
Yes. PEEK withstands repeated autoclave cycles at 134°C and 2 bar pressure — one of the few thermoplastics suitable for this sterilization method. It resists hydrolysis in steam environments, making it standard for reusable surgical instruments and dental components.
What is the difference between PEEK and PEKK?
PEKK (polyetherketoneketone) has a higher glass transition temperature (165°C vs 143°C for PEEK) and can be processed at lower temperatures due to its lower crystallization rate. PEKK offers comparable chemical resistance but different crystallization behavior — it can be quenched to an amorphous state more easily than PEEK. PEKK costs 20-40% more than PEEK.
Can PEEK be machined instead of injection molded?
Yes. PEEK is readily machined on CNC equipment using carbide or diamond tooling. Machined PEEK parts are common for prototyping and low-volume aerospace components. However, machining generates significant material waste (PEEK costs $150+/kg), so injection molding is more economical for volumes above 500-1000 pieces.
Does PEEK outgas in vacuum environments?
PEEK has exceptionally low outgassing characteristics — TML (Total Mass Loss) below 1.0% and CVCM (Collected Volatile Condensable Materials) below 0.1% per ASTM E595. This makes PEEK suitable for satellite and space applications where vacuum compatibility is required.
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References & Industry Standards
- ASTM International. Standard Specifications for Engineering Plastics & Thermoplastics. astm.org
- UL Prospector. Plastics & Elastomers Material Database. ulprospector.com
- MatWeb. Material Property Data for Engineering Thermoplastics. matweb.com
- ISO 1043. Plastics — Symbols and Abbreviated Terms. iso.org