Unravelling Polymers

The Definitive Blog on Polymers by Poly Fluoro Ltd.

PTFE vs PEEK - A Comparison of Properties

Although both PTFE and PEEK are well established within their respective fields, there are frequently questions around which would better suit a given application. OEMs typically have to make a choice based on technical suitability and hence need to be better informed as to how these materials match up against each other.

Below is a short comparison on properties between these two polymers and can be used a guide to aid new product development.

Parameter PTFE PEEK Preferred material
Price Moderately expensive Very expensive PTFE
Tensile Strength 25-35 Mpa 90-100 Mpa PEEK
Elongation 350-400% 30-40% PTFE
Compressive Strength 30-40 Mpa 140 Mpa PEEK
Flexural Modulus 495 Mpa 3900 Mpa PEEK
Coefficient of Friction 0.03-0.05 0.35-0.45 PTFE
Temperature resistance Up to 250°C Up to 250°C NA
Dielectric strength 50-150 Kv/mm 50 Kv/mm PTFE
Chemical resistance Virtually inert Affected by Sulphuric acid PTFE
Coefficient of linear thermal expansion 14 x 10-5/K 5 x 10-5/K PEEK
Machine-ability Good Very good PEEK

In a nutshell, applications requiring strength and low levels of deformation would usually employ PEEK, whereas those requiring resistance to voltage or chemicals utilize PTFE. PTFE also rates highly in that it is self-lubricating. This makes it a preferred choice in high wear applications.

The biggest disadvantage of PEEK remains the price. It is roughly 10 times the price of PTFE and as a result has remained a niche polymer, used only in applications where it is absolutely necessary.

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