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.
