Peek, also known as Polyether Ether Ketone, is a colourless organic thermoplastic polymer in the polyaryletherketone family that is used frequently in engineering applications. It is a semicrystalline thermoplastic with excellent mechanical and chemical resistance properties that are retained to high temperatures. The processing to mould Peek can influence the crystallinity, hence the mechanical properties.

Peek is highly resistant to thermal degradation, and due to its robustness it is used to fabricate items used in demanding applications including bearings, piston parts and pumps, and many more. It is also one of the few plastics compatible with ultra-high vacuum applications. Peek is extensively used in the aerospace, automotive, and chemical process industries.

It is available in a variety of grades that offer enhanced properties for specific uses. Take Glass Fibre Reinforced Peek as an example; it has a reduced expansion rate, increased flexural modulus, and excellent electrical and thermal insulation characteristics. Carbon Fibre Reinforced Peek has the highest strength and stiffness properties, outstanding wear resistance, and load carrying capabilities along with higher thermal conductivity.

Companies are often surprised at the cost of Peek plastic, as it is one of the most expensive polymers on the market; however, the cost reflects its quality. Due to its high temperature resistance and high strength, it machines more like a metal than a polymer. This can make it difficult and costly to process through methods such as injection moulding, but in its solid state Peek is readily machinable by CNC machines.


Only certain grades of Peek are FDA approved, but this approval is for parts to be used within food processing machinery only.


Peek is recyclable, and as the use of thermosetting polymers is only increasing, it is becoming important to find ways to dispose of and recycle them without it becoming a major global concern. There are different recycling treatments available. The incineration process, for example, is a treatment with considerable non-combustible residues. The chemical recycling process, however, is a proven effective recycling method for plastics. Further research is ongoing, and Peek is not being recycled extensively at present.


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