PEEK
Density Density The mass density or density of a material is defined as its mass per unit volume. The symbol most often used for density is ρ . In some cases , density is also defined as its weight per unit volume; although, this quantity is more properly called specific weight...	1320 kg/m3
Young's modulus Young's modulus Young's modulus is a measure of the stiffness of an elastic material and is a quantity used to characterize materials. It is defined as the ratio of the uniaxial stress over the uniaxial strain in the range of stress in which Hooke's Law holds. In solid mechanics, the slope of the stress-strain...  (E)	3.6 G Giga Giga is a unit prefix in the metric system denoting a factor of billion . It has the symbol G.Giga is derived from the Greek γίγας, meaning 'giant'... Pa Pascal (unit) The pascal is the SI derived unit of pressure, internal pressure, stress, Young's modulus and tensile strength, named after the French mathematician, physicist, inventor, writer, and philosopher Blaise Pascal. It is a measure of force per unit area, defined as one newton per square metre...
Tensile strength Tensile strength Ultimate tensile strength , often shortened to tensile strength or ultimate strength, is the maximum stress that a material can withstand while being stretched or pulled before necking, which is when the specimen's cross-section starts to significantly contract...  (σt)	90-100 MPa Pascal (unit) The pascal is the SI derived unit of pressure, internal pressure, stress, Young's modulus and tensile strength, named after the French mathematician, physicist, inventor, writer, and philosopher Blaise Pascal. It is a measure of force per unit area, defined as one newton per square metre...
Elongation @ break	50%
notch test	55 kJ Joule The joule ; symbol J) is a derived unit of energy or work in the International System of Units. It is equal to the energy expended in applying a force of one newton through a distance of one metre , or in passing an electric current of one ampere through a resistance of one ohm for one second... /m2
Glass temperature	143 °C
melting point Melting point The melting point of a solid is the temperature at which it changes state from solid to liquid. At the melting point the solid and liquid phase exist in equilibrium. The melting point of a substance depends on pressure and is usually specified at standard atmospheric pressure...	~343 °C
Thermal Conductivity	0.25 W/m.K Kelvin The kelvin is a unit of measurement for temperature. It is one of the seven base units in the International System of Units and is assigned the unit symbol K. The Kelvin scale is an absolute, thermodynamic temperature scale using as its null point absolute zero, the temperature at which all...
Water absorption, 24 hours (ASTM D 570)	- 0.1%
source:

Polyether ether ketone (PEEK) is a colourless organic

Organic compound

An organic compound is any member of a large class of gaseous, liquid, or solid chemical compounds whose molecules contain carbon. For historical reasons discussed below, a few types of carbon-containing compounds such as carbides, carbonates, simple oxides of carbon, and cyanides, as well as the...

 polymer

Polymer

A polymer is a large molecule composed of repeating structural units. These subunits are typically connected by covalent chemical bonds...

 thermoplastic

Thermoplastic

Thermoplastic, also known as a thermosoftening plastic, is a polymer that turns to a liquid when heated and freezes to a very glassy state when cooled sufficiently...

 used in engineering applications.

Synthesis

PEEK polymers are obtained by step-growth polymerization

Step-growth polymerization

Step-growth polymerization refers to a type of polymerization mechanism in which bi-functional or multifunctional monomers react to form first dimers, then trimers, longer oligomers and eventually long chain polymers. Many naturally occurring and some synthetic polymers are produced by step-growth...

 by the dialkylation

Alkylation

Alkylation is the transfer of an alkyl group from one molecule to another. The alkyl group may be transferred as an alkyl carbocation, a free radical, a carbanion or a carbene . Alkylating agents are widely used in chemistry because the alkyl group is probably the most common group encountered in...

 of bisphenol

Phenol

Phenol, also known as carbolic acid, phenic acid, is an organic compound with the chemical formula C6H5OH. It is a white crystalline solid. The molecule consists of a phenyl , bonded to a hydroxyl group. It is produced on a large scale as a precursor to many materials and useful compounds...

ate salts. Typical is the reaction of 4,4'-difluorobenzophenone

4,4'-Difluorobenzophenone

4,4’-Difluorobenzophenone is an organic compound with the formula of 2CO. This a colorless solid is commonly used as a precursor to PEEK, or polyetherether ketone, a so-called high performance polymer...

 with the disodium salt of hydroquinone

Hydroquinone

Hydroquinone, also benzene-1,4-diol or quinol, is an aromatic organic compound that is a type of phenol, having the chemical formula C6H42. Its chemical structure, shown in the table at right, has two hydroxyl groups bonded to a benzene ring in a para position. It is a white granular solid...

, which is generated in situ by deprotonation with sodium carbonate

Sodium carbonate

Sodium carbonate , Na2CO3 is a sodium salt of carbonic acid. It most commonly occurs as a crystalline heptahydrate, which readily effloresces to form a white powder, the monohydrate. Sodium carbonate is domestically well-known for its everyday use as a water softener. It can be extracted from the...

. The reaction is conducted around 300 °C in polar aprotic solvents - such as diphenylsulphone.

Properties

PEEK is a semicrystalline thermoplastic

Thermoplastic

Thermoplastic, also known as a thermosoftening plastic, is a polymer that turns to a liquid when heated and freezes to a very glassy state when cooled sufficiently...

 with excellent mechanical and chemical resistance properties that are retained to high temperatures. The Young's modulus

Young's modulus

Young's modulus is a measure of the stiffness of an elastic material and is a quantity used to characterize materials. It is defined as the ratio of the uniaxial stress over the uniaxial strain in the range of stress in which Hooke's Law holds. In solid mechanics, the slope of the stress-strain...

 is 3.6 GPa and its tensile strength 90 to 100 MPa. PEEK has a glass transition temperature at around 143 °C (289 °F) and melts around 343 °C (662 °F). It is highly resistant to thermal degradation as well as attack by both organic and aqueous environments. It is attacked by halogens and strong Bronsted and Lewis acid

Lewis acid

]The term Lewis acid refers to a definition of acid published by Gilbert N. Lewis in 1923, specifically: An acid substance is one which can employ a lone pair from another molecule in completing the stable group of one of its own atoms. Thus, H+ is a Lewis acid, since it can accept a lone pair,...

s as well as some halogenated compounds and aromatic hydrocarbons at high temperatures.

Applications

Because of its robustness, PEEK is used to fabricate items used in demanding applications, including bearings

Bearing (mechanical)

A bearing is a device to allow constrained relative motion between two or more parts, typically rotation or linear movement. Bearings may be classified broadly according to the motions they allow and according to their principle of operation as well as by the directions of applied loads they can...

, piston

Piston

A piston is a component of reciprocating engines, reciprocating pumps, gas compressors and pneumatic cylinders, among other similar mechanisms. It is the moving component that is contained by a cylinder and is made gas-tight by piston rings. In an engine, its purpose is to transfer force from...

 parts, pumps, compressor plate valves, and cable

Cable

A cable is two or more wires running side by side and bonded, twisted or braided together to form a single assembly. In mechanics cables, otherwise known as wire ropes, are used for lifting, hauling and towing or conveying force through tension. In electrical engineering cables are used to carry...

 insulation

Electrical insulation

thumb|250px|[[Coaxial Cable]] with dielectric insulator supporting a central coreThis article refers to electrical insulation. For insulation of heat, see Thermal insulation...

. It is one of the few plastics compatible with ultra-high vacuum applications. PEEK is considered an advanced biomaterial used in medical implants. It is extensively used in the aerospace, automotive, teletronic, and chemical process industries. PEEK's mechanical properties at elevated temperatures have lead to it being used in at least two varieties of Reprap extruder as thermal insulation. This means the rest of the extruder structure can be made of the same material as the object being fabricated without self-destruction.

Shape memory PEEK in biomechanical applications

PEEK is not traditionally a shape memory polymer

Shape Memory Polymer

Shape-memory polymers are polymeric smart materials that have the ability to return from a deformed state to their original shape induced by an external stimulus , such as temperature change....

, however, recent advances in processing have allowed shape memory behavior in PEEK with mechanical activation. This technology has expanded to applications in orthopedic surgery

Orthopedic surgery

Orthopedic surgery or orthopedics is the branch of surgery concerned with conditions involving the musculoskeletal system...

.