Polyetheretherketone (PEEK)

This is commonly used with continuous carbon fibre reinforcement. Hot/wet properties and impact resistance are good, with generally very low water absorption. The presence of fibres in the semi-crystalline material causes additional crystallisation, so that the failure strain is reduced, but the yield strength is increased. Melt processing is required as this is a solid material - with temperatures up to 400C needed. Fracture toughness is up to 100 times that of epoxies. Continuous use temperatures of 250C and above are quoted.

The crystallinity means that PEEK does not dissolve in (but may absorb) common solvents.