PEEK material (polyetheretherketone) is a high-performance semi-crystalline engineering thermoplastic with outstanding harsh chemical resistance, very low moisture uptake, good fire performance, excellent mechanical strength across a broad temperature range, and good dimensional stability. The crystalline nature of PEEK contributes to its outstanding properties.

PEEK plastic is tough, strong, and rigid, with superior creep resistance, and is excellent for applications where thermal, chemical, and combustion properties are critical to performance. PEEK material retains its stiffness and strength for use in harsh high-pressure and high-temperature (HPHT) environments. For example, Arlon® 3000 XT, Greene Tweed’s proprietary cross-linked PEEK, has proven creep and extrusion resistance at temperatures above 350oF (177 oC).

Greene Tweed was the first company to use PEEK material to withstand the harsh conditions of many oilfield applications. PEEK is often used as the body for electrical connectors to minimize thermal expansion, provide chemical resistance, and to promote effective sealing. Greene Tweed also uses PEEK materials for a variety of sealing system components, as well as sensor housings and numerous high-performance applications in aircraft engines and other demanding environments.


Polyetherketone (PEK) is a ketone-based, semi-crystalline, high-performance engineering thermoplastic. With its high thermal dimensional stability, low flammability, outstanding chemical resistance, and excellent mechanical properties over a wide temperature range, PEK is often used for demanding applications in a variety of markets.

Because PEK retains its strength as temperatures rise, it is often used in applications with vibrational or cyclic loading conditions and where components must withstand high mechanical loads at high temperatures for extended periods of time, such as gears, shafts, bushes, bearings, and miniature rotational precision parts in the aerospace and automotive industries.

Compared to traditional PEEK material, the mechanical and physical properties of PEK remain almost constant at up to 30°C higher in temperature. These properties, combined with good creep and fatigue resistance, provide a property set uncommon in most other polymers.

Like PEEK, PEK is also often used as the body for electrical connectors to minimize thermal expansion, provide chemical resistance, and to promote effective sealing.


PTFE (polytetrafluoroethylene) belongs to the fluoropolymer family, which is distinct from poly ether ketones. The presence of fluorine provides even greater chemical resistance, especially to strong acids, and results in a low coefficient of friction, low moisture absorption, and high electrical resistance.  PTFE mechanical properties are low compared to other polymers, but its flexibility at low temperatures is a key feature.  PTFE is stable at temperatures up to 500oF (260°C)

PTFE is commonly used in back-up rings and as a component of specialty seals within a wide range of markets. PTFE is also used for low friction bearing components and electrical insulation or isolation.  High purity grades are used extensively in fluid handling systems in the semiconductor market.


Arlon® 3000 XT, patented by Greene Tweed, is a non-filled, cross-linked thermoplastic material that maintains all of the expected benefits of conventional PEEK and PEK polymers while providing extended mechanical, electrical, and creep performance at high temperatures above 300oF (150oC).

Arlon® 3000 XT’s electrical resistivity properties, in addition to its performance and reliability in high temperature  environments, make it the superior choice for safeguarding mission-critical operations in the most severe applications. When it comes to high-temperature and high-voltage applications, Arlon® 3000 XT has expanded capability beyond what PEEK and PEK solutions have traditionally provided.

Unlike other thermoplastic on the market, Arlon® 3000 XT has been proven to have 100 times the electrical resistivity of PEEK and 30 times that of PEK at temperatures of 400˚F and above. At room temperature, Arlon® 3000 XT has extended capabilities above 20kV. Please visit www.arlon3000xt.com for more information.

PTFE vs. PEK vs. PEEK vs. Arlon® 3000 XT Comparison Table

Download this comparison chart here.

PropertyASTM StandardUnitsPTFE (Unfilled)PEKPEEKArlon® 3000 XT
Specific gravityD792---2.151.321.301.29
Hardness, Shore DD2240Points55908788
Izod impact, notchedD256ft-lbf/inch3.51.11.381.64
Izod impact, unnotchedD4812ft-lbf/inch------No break37.8
Water absorption @ 24-hr, change in weightD570%<0.01---0.070.09
Coefficient of friction dynamic, PV=5,000D3702psi-ft/min0.10 0.240.56 0.60
Wear factor, PV=5,000D3702psi-ft/min x 10-10in3 min/ (ft-lb-hr)------451.4110.6
Heat deflection temperature @ 264 psi (1.83 MPa)*D648°F/°C---329/165338/170>572/>300
Melting point (Tm), by DSC (differential scanning calorimetry)D3418°F/°C------649/343665/352
Tensile yield strength @ 500°F/260°CD638, Type 1psi/MPa---3,600/252,600/183,820/28
Tensile strength @ break, @ 500°F/260°CD638, Type 1psi/MPa---6,400/446,100/425,380/38
Tensile elongation @ break, @ 500°F/260°CD638%------>40>25
Tensile modulus @ 500°F/260°CD638 psi/MPa------38,700/26788,100/607
Flexural strength @ 5% strain, @ 500°F/260°CD790psi/MPa---4,000/27.6 2,300/163,740/26
Flexural modulus @ 500°F/260°CD790psi/MPa--- 50,300/34790,200/622
Compressive strength @ 500°F D695psi/MPa ------2,590/185,500/38
Compressive modulus @ 500°FD695psi/MPa------16,900/ 117132,000/ 910
Shear strength (test performed on flex bars) @ 500°FD732psi/MPa1353,800/26.23,300/236,880/47
Coefficient of thermal expansion (axial)E831µm/m°C------46.8 (TTg)55.4 (T
Volume resistivity @ RTD257Ohm-cm>1018>1016 **>1016>1013 **
Dielectric strengthD149 V/mil 400-500391480541
Tg value---°F/°C------293/145338/170