Polyether ether ketone
semicrystalline thermoplastic with high mechanical and chemical resistance

Polyether ether ketone (PEEK) is a beige coloured organic thermoplastic polymer in the polyaryletherketone (PAEK) family, used in engineering applications. It was invented in November 1978 and brought to market in the early 1980s by part of Imperial Chemical Industries (ICI), the PEEK division was acquired through a management buyout, giving rise to Victrex PLC.
Synthesis
PEEK polymers are obtained by step-growth polymerization by the dialkylation of bisphenolate salts. Typical is the reaction of 4,4'-difluorobenzophenone with the disodium salt of hydroquinone, which is generated in situ by deprotonation with sodium carbonate. The reaction is conducted around 300 °C in polar aprotic solvents - such as diphenyl sulfone.
Properties
PEEK is a semicrystalline thermoplastic with excellent mechanical and chemical resistance properties that are retained to high temperatures. The processing conditions used to mould PEEK can influence the crystallinity and hence the mechanical properties. Its Young's modulus is 3.6 GPa and its tensile strength is 90 to 100 MPa. PEEK has a glass transition temperature of around 143 °C (289 °F) and melts around 343 °C (662 °F). Some grades have a useful operating temperature of up to 250 °C (482 °F). The thermal conductivity increases nearly linearly with temperature between room temperature and solidus temperature.
The public source identifies “Polyether ether ketone” as semicrystalline thermoplastic with high mechanical and chemical resistance. This brief keeps that definition visible, then builds a research path around Polyether, ether and ketone.
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The date and method of observation matter as much as the stated conclusion, especially where classification or consensus has changed. The source revision retrieved here is dated Jul 21, 2026. The linked authority identifier is Q145387. None of the 0 selected statements returned an explicit reference. The first chronological checks are 1978.
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This entry incorporates text from “Polyether ether ketone” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.