Polyether ether ketone

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Polyether ether ketone
Polyetherketon.svg
Identifiers
PubChem CID
Properties
(C19H12O3)n
Molar mass 288.3 g/mol
Density 1.32 g/cm3
Melting point 343 °C (649 °F; 616 K)
Related compounds
Related compounds
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Polyether ether ketone
Physical properties
Density (ρ)1.32 g/cm3
Water absorption—over 24 hours0.1%
Mechanical properties
Young's modulus (E)3.6  GPa
Tensile strength (σt)90–100  MPa
Elongation (ε)at break 50%
Notch test 55 kJ/m2
Thermal properties
Melting temperature (Tm)343 °C
Glass transition temperature (Tg)143 °C
Thermal conductivity (k)0.25  W/(mK)
[1]

Polyether ether ketone (PEEK) is a colourless organic thermoplastic polymer in the polyaryletherketone (PAEK) family, used in engineering applications. It was invented in November 1978 [2] 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. [3]

Contents

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. [4] [5]

Synthesis of PEEK.svg

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. [6] 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). [4] The thermal conductivity increases nearly linearly with temperature between room temperature and solidus temperature. [7] It is highly resistant to thermal degradation, [8] as well as to attack by both organic and aqueous environments. It is attacked by halogens and strong Brønsted and Lewis acids, 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 bearings, piston parts, pumps, high-performance liquid chromatography columns, compressor plate valves, and electrical cable insulation. It is one of the few plastics compatible with ultra-high vacuum applications, which makes it suitable for aerospace, automotive, and chemical industries. [9] PEEK is used in medical implants, for example in creating a partial replacement skull in neurosurgical applications.

PEEK is used in spinal fusion devices and reinforcing rods. [10] It is radiolucent, but it is hydrophobic causing it to not fully fuse with bone. [9] [11] PEEK seals and manifolds are commonly used in fluid applications. PEEK also performs well in high temperature applications (up to 260 °C/500 °F). [12] 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 °C / 649.4 °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. [13] [14] PEEK filaments have been demonstrated for producing medical devices up to class IIa. [15] 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 polymer, but its high price, due to its complex production process, restricts its use to only the most demanding applications. [16]

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. [17]

Related Research Articles

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Polyurethane refers to a class of polymers composed of organic units joined by carbamate (urethane) links. In contrast to other common polymers such as polyethylene and polystyrene, polyurethane term does not refer to the single type of polymer but a group of polymers. Unlike polyethylene and polystyrene polyurethanes can be produced from a wide range of starting materials resulting various polymers within the same group. This chemical variety produces polyurethanes with different chemical structures leading to many different applications. These include rigid and flexible foams, and coatings, adhesives, electrical potting compounds, and fibers such as spandex and polyurethane laminate (PUL). Foams are the largest application accounting for 67% of all polyurethane produced in 2016.

<span class="mw-page-title-main">Thermoplastic</span> Plastic that softens with heat and hardens on cooling

A thermoplastic, or thermosofteningplastic, is any plastic polymer material that becomes pliable or moldable at a certain elevated temperature and solidifies upon cooling.

<span class="mw-page-title-main">Acrylonitrile butadiene styrene</span> Thermoplastic polymer

Acrylonitrile butadiene styrene (ABS) (chemical formula (C8H8)x·​(C4H6)y·​(C3H3N)z ) is a common thermoplastic polymer. Its glass transition temperature is approximately 105 °C (221 °F). ABS is amorphous and therefore has no true melting point.

<span class="mw-page-title-main">Polyethylene terephthalate</span> Polymer

Polyethylene terephthalate (or poly(ethylene terephthalate), PET, PETE, or the obsolete PETP or PET-P), is the most common thermoplastic polymer resin of the polyester family and is used in fibres for clothing, containers for liquids and foods, and thermoforming for manufacturing, and in combination with glass fibre for engineering resins.

<span class="mw-page-title-main">Thermosetting polymer</span> Polymer obtained by irreversibly hardening (curing) a resin

In materials science, a thermosetting polymer, often called a thermoset, is a polymer that is obtained by irreversibly hardening ("curing") a soft solid or viscous liquid prepolymer (resin). Curing is induced by heat or suitable radiation and may be promoted by high pressure or mixing with a catalyst. Heat is not necessarily applied externally, and is often generated by the reaction of the resin with a curing agent. Curing results in chemical reactions that create extensive cross-linking between polymer chains to produce an infusible and insoluble polymer network.

<span class="mw-page-title-main">Polylactic acid</span> Biodegradable polymer

Polylactic acid, also known as poly(lactic acid) or polylactide (PLA), is a plastic material. As a thermoplastic polyester it has the backbone formula (C
3
H
4
O
2
)
n
or [–C(CH
3
)HC(=O)O–]
n
. PLA is formally obtained by condensation of lactic acid C(CH
3
)(OH)HCOOH
with loss of water. It can also be prepared by ring-opening polymerization of lactide [–C(CH
3
)HC(=O)O–]
2
, the cyclic dimer of the basic repeating unit. Often PLA is blended with other polymers. PLA can be biodegradable or long-lasting, depending on the manufacturing process, additives and copolymers.

<span class="mw-page-title-main">Engineering plastic</span> Plastics often used for making mechanical parts

Engineering plastics are a group of plastic materials that have better mechanical or thermal properties than the more widely used commodity plastics.

Polysulfones are a family of high performance thermoplastics. These polymers are known for their toughness and stability at high temperatures. Technically used polysulfones contain an aryl-SO2-aryl subunit. Due to the high cost of raw materials and processing, polysulfones are used in specialty applications and often are a superior replacement for polycarbonates.

<span class="mw-page-title-main">Polyester</span> Category of polymers, in which the monomers are joined together by ester links

Polyester is a category of polymers that contain one or two ester linkages in every repeat unit of their main chain. As a specific material, it most commonly refers to a type called polyethylene terephthalate (PET). Polyesters include naturally occurring chemicals, such as in plants and insects, as well as synthetics such as polybutyrate. Natural polyesters and a few synthetic ones are biodegradable, but most synthetic polyesters are not. Synthetic polyesters are used extensively in clothing.

Thermoplastic elastomers (TPE), sometimes referred to as thermoplastic rubbers (TPR), are a class of copolymers or a physical mix of polymers that consist of materials with both thermoplastic and elastomeric properties.

Polymer engineering is generally an engineering field that designs, analyses, and modifies polymer materials. Polymer engineering covers aspects of the petrochemical industry, polymerization, structure and characterization of polymers, properties of polymers, compounding and processing of polymers and description of major polymers, structure property relations and applications.

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Polyaryletherketone (PAEK) is a family of semi-crystalline thermoplastics with high-temperature stability and high mechanical strength whose molecular backbone contains alternately ketone (R-CO-R) and ether groups (R-O-R). The linking group R between the functional groups consists of a 1,4-substituted aryl group.

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<span class="mw-page-title-main">High-performance plastics</span> Plastics that meet higher requirements than engineering plastics

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<span class="mw-page-title-main">Acrylonitrile styrene acrylate</span> Chemical compound

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<span class="mw-page-title-main">Fused filament fabrication</span> 3D printing process

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<span class="mw-page-title-main">Polymer derived ceramics</span>

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References

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  3. "Why PEEK?". drakeplastics.com. Retrieved 23 April 2018.
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  5. Kemmish, David (2010). Update on the Technology and Applications of PolyArylEtherKetones. ISmithers. ISBN   978-1-84735-408-2.
  6. Material Properties Data: Polyetheretherketone (PEEK), www.makeitfrom.com.
  7. Blumm, J.; Lindemann, A.; Schopper, A. (2008). "Influence of the CNT content on the thermophysical properties of PEEK-CNT composites". Proceedings of the 29th Japan Symposium on Thermophysical Properties, October 8–10, 2008, Tokyo. pp. 306–8. ISSN   0911-1743.
  8. Patel, Parina; Hull, T. Richard; McCabe, Richard W.; Flath, Dianne; Grasmeder, John; Percy, Mike (May 2010). "Mechanism of thermal decomposition of poly(ether ether ketone) (PEEK) from a review of decomposition studies" (PDF). Polymer Degradation and Stability. 95 (5): 709–718. doi:10.1016/j.polymdegradstab.2010.01.024.
  9. 1 2 "PEEK (Polyether Ether Ketone)". www.scientificspine.com. Retrieved 2020-05-06.
  10. Lauzon, Michael (May 4, 2012). "Diversified Plastics Inc., PEEK playing role in space probe". PlasticsNews.com. Crain Communications Inc . Retrieved May 6, 2012.
  11. "10 Porous TLIF cages to Know...!". SPINEMarketGroup. 2020-02-01. Retrieved 2020-05-06.
  12. "Properties of PEEK Material". www.uplandfab.com.
  13. Newsom, Michael (24 March 2014). "Arevo Labs announces Carbon Fiber and Nanotube-reinforced High Performance materials for 3D Printing Process". Solvay Press Releases. LouVan Communications Inc. Retrieved 27 January 2016.
  14. Thryft, Ann. "3D Printing High-Strength Carbon Composites Using PEEK, PAEK". Design News. Retrieved 27 January 2016.
  15. Press release Indmatec PEEK MedTec.
  16. Yin, Jun; Zhang, Aiqing; Liew, Kong Yong; Wu, Lihua (2008). "Synthesis of poly(ether ether ketone) assisted by microwave irradiation and its characterization". Polymer Bulletin. 61 (2): 157–163. doi:10.1007/s00289-008-0942-6. ISSN   1436-2449. S2CID   97563069.
  17. Anonymous. "Surgical Technologies; MedShape Solutions, Inc. Announces First FDA-cleared Shape Memory PEEK Device; Closing of $10M Equity Offering". Medical Letter on the CDC & FDA.