PEEK vs PEKK: Which High Performance Material Should You Choose?

PEEK and PEKK are high performance polymers, known for their strength and thermal properties, that are increasingly used in additive manufacturing industry. PEEK and PEKK demonstrate sufficient mechanical strength at temperatures over 250°C, and can resist deformation well above the limits of common plastics such as nylon, ABS, or PC. Because of this, these tough materials are often used in place of metal, when users want to reduce waste, prevent corrosion, and allow for more complex designs. When it comes to AM, PEEK and PEKK are compatible with material extrusion (FDM) and selective laser sintering. But what are the differences between these two high-performance thermoplastics? Which one should you choose?

PEEK and PEKK are considered high performance polymers

Composition and Characteristics

When comparing two high performance polymers, it is important to start with their composition and properties. This will help you understand how they will perform during the manufacturing process, which can be a determining factor in your choice. These two materials belong to the PAEK family, a group of high-performance semi-crystalline and amorphous thermoplastics. In this family, the most commonly used polymer is PEEK, which is formed by a molecular structure of 1 ketone and 2 ethers.

PEKK, on the other hand has an inverse molecular structure: it has 2 ketones and 1 ether. The ketone bonds are more flexible, which increases the flexibility of the polymer in question. This means that the glass transition temperature (the temperature at which the polymer starts to soften) and the melting temperature are higher with PEKK.