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What is the difference between PEKK and PEEK?
PEKK and PEEK both belong to the family of polyaryletherketones (PAEK), which is a group of high-performance semi-crystalline thermoplastics, with high mechanical strength, high temperature resistance, fatigue resistance and low flammability. But what are the differences between these two high-performance thermoplastics? Which one should you choose? Today we will explain to you as below points:
When comparing two high performance polymers, it is important to start with their composition&properties. This is in order to understand how they will perform during the manufacturing process, which can be a determining factor in your choice. The PEKK is formed by a molecular structure of 2 ketones and 1 ether, In contrast, the PEEK is formed by a molecular structure of 1 ketone and 2 ethers. The ketone structure increases the flexibility of the polymer. This means the glass transition temperature (the temperature at which the polymer starts to soften) and the melting temperature are higher with PEKK. Henri de Vries, Senior Composite Scientist at the Netherlands Aerospace Center (NLR) Structural Technology Department, said: “PEKK and PEEK have similar appearances and similar crystallization behavior, but the process temperatures are different, PEKK is 375°C and PEEK is 385°C”.
Relating to the characteristics, almost is the same but PEKK, this thermoplastic is more resistant to chemical fluids, has good dielectric stability and does not emit toxic fumes. On the other hand, PEEK has excellent mechanical properties and a good strength-to-weight ratio, making it a good substitute for some metals. Both polymers can be sterilized, facilitating their use in healthcare applications.
To sum up, PEKK and PEEK with the common properties, owing to they belong to the same family of polymers. Whereas, some of their characteristics different due to their composition, the main distinction between these two materials are their degree of crystallinity.
Applications
Relating to the use of PEKK and PEEK, we can find similar application sectors, which are mostly for aerospace, automotive, and aviation, due to the aforementioned advanced characteristics, such as mechanical and high-pressure resistance, lightness, rigidity, among others. Being bio-compatible, they are often used in the medical sector. PEKK has better resistance to chemical fluids, which is why it will be used more in the oil and gas industry. It can also be fire/smoke certified for the railway industry. On the other hand, PEEK has properties that facilitate osseointegration, i.e. the direct, structural and functional connection between a bone and the surface of an implant under functional load.
The cost of PEKK and PEEK
As you can imagine, PEKK and PEEK are more expensive than most polymers on the market due to their properties and characteristics. On average, PEKK will cost you about $415 to 480, while the same amount of PEEK, a 500 gram roll of PEEK will cost you about $350 to 420. Of course, if you buy a high-performance, carbon-fiber reinforced polymer, the price will be even higher.
Therefore, please make sure that the 3D file is perfect with the correct printing parameters. The Mistakes can be expensive!
To summarize,
The properties of PEKK: