PEEK vs PTFE: Which High-Performance Plastic Is Right for Your Application?

Where PEEK Excels

PEEK is the clear winner when your application demands:

Structural Performance Under Load

With 3–5× the tensile and flexural strength of PTFE, PEEK maintains mechanical integrity under sustained loads at elevated temperatures. This makes it ideal for structural brackets, bearing cages, and load-bearing seals.

High-Temperature Mechanical Stability

PEEK retains over 50% of its room-temperature strength at 200°C, while PTFE‘s already-low strength drops dramatically above 150°C. For components that must carry load at high temperatures, PEEK is the only option.

Dimensional Precision

PEEK‘s low creep and moisture absorption ensure tight tolerances are maintained over the component’s service life. PTFE exhibits significant cold flow (creep) even under moderate loads, making it unsuitable for precision dimensional applications.

Regulatory Compliance

PEEK meets FDA, USP Class VI, and ISO 10993 standards for medical and food contact. While PTFE is also FDA compliant, PEEK offers a broader regulatory profile for implantable devices.

Where PTFE Excels

PTFE is the better choice when your application requires:

Ultimate Chemical Inertness

PTFE is virtually chemically inert, resisting attack from virtually all acids, bases, and solvents at temperatures up to 260°C. PEEK, while excellent, can be attacked by concentrated sulfuric acid and some halogenated solvents.

Lowest Friction Coefficient

With a coefficient of friction of 0.05–0.10, PTFE is one of the slipperiest solids known. For sliding bearings, non-lubricated guides, and release surfaces, PTFE outperforms PEEK (0.35 unfilled, 0.15 with PTFE additive).

Cost-Sensitive Chemical Resistance

PTFE costs roughly 30–50% less than PEEK, making it the preferred choice when chemical resistance is the primary requirement and mechanical strength is secondary.

Electrical Insulation at High Frequency

PTFE has a very low dielectric constant (2.1) and dissipation factor, making it ideal for RF/microwave applications. PEEK‘s dielectric properties are good but inferior to PTFE for high-frequency electronics.

Filled Grade Considerations

Both materials benefit from fillers:

l PEEK + 30% glass fibre (GF30): Doubles flexural modulus, ideal for structural parts

l PEEK + 30% carbon fibre (CF30): Adds static dissipativity, highest stiffness

l PEEK + PTFE + graphite: Excellent bearing material, combines PEEK strength with PTFE lubricity

l PTFE + glass/carbon: Improves wear and creep resistance, but remains structurally inferior