View source for Polyether ether ketone

{{Short description|Semicrystalline thermoplastic with high mechanical and chemical resistance}}
{{redirect|PEEK|the command in computing|PEEK and POKE}}
{{Chembox
| Name           = Polyether ether ketone
| ImageFile      = Polyetherketon.svg
| ImageClass     = skin-invert
| Section1       = {{ Chembox Identifiers
| PubChem = 19864017
| CASNo = 31694-16-3
  }}
| Section2       = {{Chembox Properties
| Formula        = (C<sub>19</sub>H<sub>12</sub>O<sub>3</sub>)<sub>n</sub>
| MolarMass      = 288.3 g/mol
| Density        = {{convert|1320|kg/m3|g/cm3|disp=out}}
| MeltingPtC     = 343
  }}
| Section9       = {{Chembox Related
| OtherCompounds = {{Unbulleted list|[[Hydroquinone]]|[[4,4'-Difluorobenzophenone]]}}
  }}
}}
{{Infobox material
|name=Polyether ether ketone
|density={{convert|1320|kg/m3|g/cm3|disp=out}}
|water_absorption_24h=0.1%
|youngs_modulus=3.6&nbsp;[[GPa]]
|tensile_strength=90–100&nbsp;[[MPa]]
|elongation=50%
|notch_test=55&nbsp;kJ/m<sup>2</sup>
|melting_point=343&nbsp;°C
|glass_transition=143&nbsp;°C
|thermal_conductivity=0.25&nbsp;[[watt|W]]/([[metre|m]]⋅[[kelvin|K]])
|footnotes=<ref>{{cite book |first1=A.K. |last1=van der Vegt |first2=L.E. |last2=Govaert |title=Polymeren, van keten tot kunstof |language=dutch |date=2003 |publisher=DUP Blue |edition=5th |isbn=90-407-2388-5 |url=https://research.tue.nl/en/publications/polymeren-van-keten-tot-kunststof}}</ref>
}}
'''Polyether ether ketone''' ('''PEEK''') is a beige coloured [[organic compound|organic]] [[thermoplastic]] [[polymer]] in the [[polyaryletherketone]] (PAEK) family, used in engineering applications. It was invented in November 1978<ref>{{Cite web|title=Victrex celebrates 40 years of PEEK success|url=https://www.victrex.com/en/news/2018/11/40-years-of-peek-success|access-date=2021-11-01|website=Victrex|language=en}}</ref> and brought to market in the early 1980s by part of [[Imperial Chemical Industries|Imperial Chemical Industries (ICI)]], the PEEK division was acquired through a management buyout, giving rise to [[Victrex|Victrex PLC]].<ref>{{cite web|url=http://drakeplastics.com/peek/|title=Why PEEK?|website=drakeplastics.com|access-date=23 April 2018}}</ref>

==Synthesis==
PEEK polymers are obtained by [[step-growth polymerization]] by the di[[alkylation]] of bis[[phenolate]] 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&nbsp;°C in polar [[aprotic]] solvents - such as [[diphenyl sulfone]].<ref name="Polymers, High-Temperature"/><ref>{{cite book |first=David |last=Kemmish |title=Update on the Technology and Applications of PolyArylEtherKetones |date=2010 |publisher=ISmithers |isbn=978-1-84735-408-2}}</ref>

[[Image:Synthesis of PEEK.svg|class=skin-invert-image|500px]]

==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&nbsp;GPa and its tensile strength is 90 to 100&nbsp;MPa.<ref>[http://www.makeitfrom.com/material-data/?for=Polyetheretherketone-PEEK Material Properties Data: Polyetheretherketone (PEEK)], www.makeitfrom.com.</ref> PEEK has a [[glass transition temperature]] of around 143&nbsp;°C (289&nbsp;°F) and melts around 343&nbsp;°C (662&nbsp;°F). Some grades have a useful operating temperature of up to 250&nbsp;°C (482&nbsp;°F).<ref name="Polymers, High-Temperature">{{cite book|author=David Parker|author2=Jan Bussink|author3=Hendrik T. van de Grampe|author4=Gary W. Wheatley|author5=Ernst-Ulrich Dorf|author6=Edgar Ostlinning|author7=Klaus Reinking|title=Polymers, High-Temperature |series=Ullmann's Encyclopedia of Industrial Chemistry |date=15 April 2012| doi=10.1002/14356007.a21_449.pub3|isbn=978-3527306732}} {{subscription required}}</ref> The thermal conductivity increases nearly linearly with temperature between room temperature and [[Solidus (chemistry)|solidus]] temperature.<ref>{{cite conference |first1=J. |last1=Blumm |first2=A. |last2=Lindemann |first3=A. |last3=Schopper |title=Influence of the CNT content on the thermophysical properties of PEEK-CNT composites |book-title=Proceedings of the 29th Japan Symposium on Thermophysical Properties, October 8–10, 2008, Tokyo |date=2008 |pages=306–8 |issn=0911-1743}}</ref> It is highly resistant to [[thermal degradation]],<ref>{{cite journal |last1=Patel |first1=Parina |last2=Hull |first2=T. Richard |last3=McCabe |first3=Richard W. |last4=Flath |first4=Dianne |last5=Grasmeder |first5=John |last6=Percy |first6=Mike |title=Mechanism of thermal decomposition of poly(ether ether ketone) (PEEK) from a review of decomposition studies |journal=Polymer Degradation and Stability |date=May 2010 |volume=95 |issue=5 |pages=709–718 |doi=10.1016/j.polymdegradstab.2010.01.024|url=http://clok.uclan.ac.uk/1919/1/Hull_Patel_PEEK_Decomposition_Review_1.pdf }}</ref> as well as to attack by both organic and aqueous environments. It is attacked by halogens and strong [[Brønsted acid|Brønsted]] and [[Lewis acid]]s, as well as some halogenated compounds and aliphatic hydrocarbons at high temperatures. It is soluble in concentrated sulfuric acid at room temperature, although dissolution can take a very long time unless the polymer is in a form with a high surface-area-to-volume ratio, such as a fine powder or thin film. It has high resistance to biodegradation.

==Applications==
PEEK is used to fabricate items for demanding applications, including [[Bearing (mechanical)|bearings]], [[piston]] parts, [[pumps]], [[high-performance liquid chromatography]] columns, compressor plate [[valves]], and [[electrical cable]] [[Electrical insulation|insulation]]. It is one of the few plastics compatible with [[ultra-high vacuum]] applications, which makes it suitable for aerospace, automotive, and chemical industries.<ref name=":0">{{Cite web|title=PEEK (Polyether Ether Ketone)|url=http://www.scientificspine.com/spinal-materials/peek.html|website=www.scientificspine.com|access-date=2020-05-06}}</ref> PEEK is used in [[medical implant]]s, for example in creating a partial replacement skull in neurosurgical applications.

PEEK is used in [[spinal fusion]] devices and reinforcing rods.<ref name="space probe use">{{cite web|last=Lauzon|first=Michael|title=Diversified Plastics Inc., PEEK playing role in space probe|url=http://www.plasticsnews.com/article/20120504/NEWS/305049956|work=PlasticsNews.com|publisher=[[Crain Communications Inc]]|date=May 4, 2012|access-date=May 6, 2012}}</ref> It is [[Radiodensity|radiolucent]], but it is hydrophobic causing it to not fully fuse with bone.<ref name=":0" /><ref>{{Cite web|title=10 Porous TLIF cages to Know...!|url=http://www.thespinemarketgroup.com/10-porous-tlif-cages-to-know/|date=2020-02-01|website=SPINEMarketGroup|language=en-US|access-date=2020-05-06}}</ref> PEEK seals and manifolds are commonly used in fluid applications. PEEK also performs well in high temperature applications (up to 260&nbsp;°C/500&nbsp;°F).<ref>{{cite web|title=Properties of PEEK Material|url=http://www.uplandfab.com/peek-machining|website=www.uplandfab.com}}</ref> Because of this and its low thermal conductivity, it is also used in [[fused filament fabrication]] (FFF) printing to thermally separate the hot end from the cold end.

==Processing options==
PEEK melts at a relatively high temperature (343&nbsp;°C / 649.4&nbsp;°F) compared to most other thermoplastics. In the range of its melting temperature it can be processed using [[injection moulding]] or [[extrusion]] methods. It is technically feasible to process granular PEEK into filament form and 3D printing parts from the filament material using [[fused deposition modeling]] – FDM (or fused filament fabrication – FFF) technology.<ref>{{cite web|last1=Newsom|first1=Michael|title=Arevo Labs announces Carbon Fiber and Nanotube-reinforced High Performance materials for 3D Printing Process|url=http://www.solvay.com/en/media/press_releases/20140324-Arevo.html|website=Solvay Press Releases|date=24 March 2014 |publisher=LouVan Communications Inc.|access-date=27 January 2016}}</ref><ref>{{cite web|last1=Thryft|first1=Ann|title=3D Printing High-Strength Carbon Composites Using PEEK, PAEK|url=http://www.designnews.com/author.asp?section_id=1392&doc_id=272706&dfpPParams=ind_183,industry_aero,industry_gov,industry_medical,bid_27,aid_272706&dfpLayout=blog&dfpPParams=ind_183,industry_aero,industry_gov,industry_medical,bid_27,aid_272706&dfpLayout=blog|publisher=Design News|access-date=27 January 2016|archive-date=2 February 2016|archive-url=https://web.archive.org/web/20160202074713/http://www.designnews.com/author.asp?section_id=1392&doc_id=272706&dfpPParams=ind_183,industry_aero,industry_gov,industry_medical,bid_27,aid_272706&dfpLayout=blog&dfpPParams=ind_183,industry_aero,industry_gov,industry_medical,bid_27,aid_272706&dfpLayout=blog|url-status=dead}}</ref> PEEK filaments have been demonstrated for producing medical devices up to class [[medical devices|IIa]].<ref>[http://www.indmatec.com/press/peek-filament-medtec Press release Indmatec PEEK MedTec]{{Dead link|date=December 2024 |bot=InternetArchiveBot |fix-attempted=yes }}.</ref> With this new filament, it is possible to use the FFF method for different medical applications like [[dentures]].

In its solid state PEEK is readily machinable, for example, by [[CNC]] [[milling machines]] and is commonly used to produce high-quality plastic parts that are thermostable and both electrically and thermally insulating. Filled grades of PEEK can also be CNC machined, but special care must be taken to properly manage stresses in the material.

PEEK is a [[high-performance plastics|high-performance polymer]], but its high price, due to its complex production process, restricts its use to only the most demanding applications.<ref>{{Cite journal |last1=Yin |first1=Jun |last2=Zhang |first2=Aiqing |last3=Liew |first3=Kong Yong |last4=Wu |first4=Lihua |date=2008 |title=Synthesis of poly(ether ether ketone) assisted by microwave irradiation and its characterization |journal=Polymer Bulletin |volume=61 |issue=2 |pages=157–163 |doi=10.1007/s00289-008-0942-6 |s2cid=97563069 |issn=1436-2449}}</ref>

==Shape-memory PEEK in biomechanical applications==
PEEK is not traditionally a [[shape-memory polymer]]; however, recent advances in processing have allowed shape-memory behaviour in PEEK with mechanical activation. This technology has expanded to applications in [[orthopaedic surgery]].<ref>{{cite journal|author=Anonymous|title=Surgical Technologies; MedShape Solutions, Inc. Announces First FDA-cleared Shape Memory PEEK Device; Closing of $10M Equity Offering|journal=Medical Letter on the CDC & FDA}}</ref>

==References==
<references/>

{{Plastics}}

[[Category:Polyethers]]
[[Category:Organic polymers]]
[[Category:Thermoplastics]]
[[Category:Fused filament fabrication]]