PEEK (Polyether Ether Ketone)

Polyether ether ketone (PEEK) is an organic polymer thermoplastic used in engineering applications and medical implants.
  • Synthesis: PEEK polymers are produced by step-growth polymerization by the dialkylation of bisphenolate salts.
  • Properties: PEEK is a colorless semicrystalline thermoplastic with excellent mechanical and chemical resistance properties. The Young's modulus is 3.6 GPa and its tensile strength 90 to 100 MPa (see below). It is highly resistant to thermal degradation as well as attack by both organic and aqueous environments.
    Density                            1320 kg/m3
    Young's modulus (E)       3.6 GPa
    Tensile strength (σt)       90-100 MPa
    Elongation @ break         50%
    Notch test                        55 kJ/m2
    Glass temperature           143 °C
    Melting point                     ~343 °C
    Thermal Conductivity        0.25 W/m.K
    Water absorption, 24 hours (ASTM D 570)     - 0.1%
  • Usage: Because of its strength, PEEK is used to fabricate items used in demanding applications, including bearings, piston parts, pumps, compressor plate valves, and cable insulation. It is one of the few plastics compatible with ultra-high vacuum applications. Thus, it is used in the aerospace, automotive, teletronic, and chemical process industries, extensively. PEEK is also considered an advanced biomaterial used in medical implants.
  • In the spine area, it is mainly used for production of interbody cages, and recently, outer coverings of the rods. When used in production of cages, its advantages include its similar Young's modulus to that of the bone. Thus, the risk of cage subsidence is lower than that of metallic cages. Another advantage of the PEEK cage is that it is radiolucent. Its main disadvantage is that its hydrophobic nature. Thus, it will never bonds to bone, unlike titanium. Therefore, to achieve a solid fusion, one has to select afiller (inside the cage) that has a high likelihood of fusing.

1. A.K. van der Vegt & L.E. Govaert, Polymeren, van keten tot kunstof, ISBN 90-407-2388-5
2. Material Properties Data: Polyetheretherketone (PEEK)

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