PolyEtherEther-Ketone (PEEK) belongs to the family of polyaryletherketones. It is one of the more expensive thermoplastics, but is vastly superior to other thermoplastics. PEEK is used in numerous industrial applications, for example in pump elements, compressors, bearings and valves. Temperatures of up to 300°C are permissible for short periods of time, making PEEK suitable for use in applications like motor vehicle gearboxes. Thanks to the low emission of smoke and toxic gases during fires, PEEK is also frequently used as a coating for cables in aircraft and defence materiel. The low absorption of moisture at high temperatures makes PEEK ideally suited to medical applications.
PEEK is a semi-crystalline engineering plastic capable of withstanding 220°C continuously and 330°C briefly. The glass transition temperature is 143°C and the melting point is 334°C. Only certain polyamides can match these values.
PEEK’s moisture absorption is extremely low, i.e. 0.2% at 23°C/50% RH and 0.5% when saturated. Size changes caused by moisture absorption are therefore negligible.
To a high degree PEEK is resistant to aggressive influences at high temperatures. Exceptions to this rule are chlorine/bromide (water), fluoride, HF and HBr, concentrated sulphur and salpater acids, certain ketones and nitrobenzene at 200°C. Exposure to UV radiation causes degradation of the material, but this is avoidable by applying a top coating of pigment of special carbon black particles. The flammability of PEEK is extremely low even without additives, while the emission of smoke on combustion is the lowest of all thermoplastics.
PEEK combines excellent rigidity and strength with high impact resistance. Deformation, even at high temperatures, is minimal for a semi-crystalline polymer. At temperatures up to approximately 200°C, PEEK retains its high electrical resistance, making the material suitable for electrical applications under aggressive conditions.