PEEK vs PAEK: Which High-Performance Plastic Wins?
Tensile data verified against MatWeb.com database & manufacturer datasheets · Last updated July 2026
Published: 2026-08-07
Which Material Should You Choose?Choose PEEK if:a different PAEK variant is the better choicegood reason: it offers the best balance of processability, mechanical properties, and costChoose PAEK if:Application requirements align with PAEK...
Which Material Should You Choose?
Choose PEEK if:
- a different PAEK variant is the better choice
- good reason: it offers the best balance of processability, mechanical properties, and cost
Choose PAEK if:
- Application requirements align with PAEK properties
Price Comparison
PEEK: $80-200/kg vs PAEK: $20-100/kg · Prices vary by grade and quantity
Compared Materials
View full material properties for each polymer:
- PEEK Polyetheretherketone — Properties, uses & cost guide
- PEKK — Properties, uses & cost guide
The term "PAEK" (polyaryletherketone) refers to an entire family of high-performance thermoplastics, of which PEEK is the most widely known member. Understanding the differences between PEEK and other PAEK variants — including PEK, PEKK, and PEKEKK — is critical for engineers specifying materials for extreme environments. This guide compares the full PAEK family and explains when to choose PEEK vs when a different PAEK variant is the better choice.
The PAEK Family Tree
| Polymer | Ketone/Ether Ratio | Tg (°C) | Tm (°C) | Continuous Use Temp | Relative Cost |
|---|---|---|---|---|---|
| PEEK | 1:2 | 143 | 343 | 260°C | Baseline (1x) |
| PEK | 1:1 | 162 | 373 | 165°C | 0.7x |
| PEKK | 2:1 | 165 | 360 | 280°C | 1.3x |
| PEKEKK | 3:2 | 175 | 385 | 290°C+ | 1.6x |
When PEEK Is the Best Choice
PEEK remains the dominant PAEK polymer for good reason: it offers the best balance of processability, mechanical properties, and cost. Its lower melting point (343°C vs 360-385°C for higher-ketone variants) makes it easier to injection mold and extrude. For most applications under 260°C, PEEK is the correct default choice — aerospace brackets, medical implants, semiconductor wafer handling, and oil & gas seals all depend on PEEK's proven performance.
When to Choose PEKK Instead
PEKK's higher ketone content gives it a 20°C edge in continuous use temperature (280°C vs 260°C) and superior compressive strength. It also crystallizes faster than PEEK, making it more amenable to additive manufacturing (3D printing) where rapid crystallization improves layer adhesion. Aerospace applications requiring FST (flame, smoke, toxicity) compliance at higher temperatures often specify PEKK over PEEK. The trade-off: PEKK costs 20-30% more and requires higher processing temperatures (370-390°C).
PEK: The Budget PAEK
PEK has the lowest continuous use temperature of the PAEK family (165°C) but compensates with a glass transition temperature (162°C) actually higher than PEEK (143°C). This unusual combination makes PEK suitable for applications requiring high Tg but modest continuous temperature — such as electrical connectors and sensor housings that see intermittent heat spikes but not sustained thermal load. PEK is approximately 30% cheaper than PEEK but is less widely available from stock.
Selection Guide: Which PAEK for Your Application?
| Application Requirement | Best PAEK Choice | Reason |
|---|---|---|
| General high-temp (≤260°C) | PEEK | Best price/performance balance; widest availability |
| Aerospace FST at >260°C | PEKK | Higher continuous use temp + superior flame resistance |
| 3D printing (FDM/SLS) | PEKK | Faster crystallization = better layer adhesion |
| Medical implant (long-term) | PEEK | Longest clinical track record; FDA Master File available |
| Electrical connector (intermittent heat) | PEK | High Tg at lower cost; intermittent use above 165°C acceptable |
| Downhole oil & gas (>280°C) | PEKEKK | Highest thermal capability in the PAEK family |
Comparison at a Glance
| Material A | PEEK |
|---|---|
| Material B | PAEK |
| Temperature Max A | 260°C |
| Temperature Max B | 280°C (PEKK variant) / 165°C (PEK variant) |
| Strength | PEEK: 100 MPa tensile; PAEK family spans 85-120 MPa |
| Cost | PEEK: $80-120/kg; PEKK: $100-150/kg |
Frequently Asked Questions
Is PEKK stronger than PEEK?
PEKK has higher compressive strength than PEEK and marginally higher tensile strength (110-120 MPa vs 100 MPa for unfilled PEEK). However, PEEK has better impact resistance and fracture toughness. The choice depends on the specific loading conditions — PEKK for compression-dominated applications, PEEK for impact and fatigue.
Can I use PEEK processing equipment for PEKK?
Generally yes, but PEKK requires higher melt temperatures (370-390°C vs 360-380°C for PEEK). Verify that your barrel, screw, and hot runner components are rated for sustained operation at 400°C. Purge thoroughly between materials — residual PEEK in a PEKK part will create a weak boundary layer.
Why is PEKK better for 3D printing than PEEK?
PEKK crystallizes approximately 30% faster than PEEK, which translates to better interlayer adhesion in FDM printing and less warpage. The faster crystallization also means the printed part develops full mechanical properties sooner during the cooling cycle. For SLS (powder bed) printing, both materials perform well but PEKK's wider processing window is more forgiving.
What is the cost difference across the PAEK family?
PEEK is the baseline at approximately $80-120/kg for unfilled grades. PEK is about 30% less ($55-85/kg). PEKK is 20-30% more ($100-150/kg). PEKEKK is 50-60% more ($130-190/kg). These are approximate ranges for standard grades — medical, implantable, and aerospace-certified grades carry significant premiums.
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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