Polyether ether ketone (PEEK): Characteristics, Features, and Process

Written by Rahul Verma | Updated: February 13, 2026

Polyether ether ketone (PEEK)

Polyether ether ketone (PEEK) plastic is a highly sought-after engineering material due to its exceptional strength, resistance, and workability. It is a semicrystalline engineering thermoplastic in the polyaryletherketone (PAEK) family, resistant to heat, chemicals, and abrasion. PEEK has a high melting point of 343 °C (649 °F) due to the use of rigid aromatic units in its production.

Because of its exceptional combination of strength, resistance, and workability, polyether ether ketone (PEEK) plastic is a highly sought-after engineering material. Polyetheretherketone (PEEK) plastic is a semicrystalline engineering thermoplastic in the polyaryletherketone (PAEK) family that is resistant to heat, chemicals, and abrasion. Its high melting point of 343 °C/649 °F is a result of the use of rigid aromatic units in its production. There are several different types of PEEK, including those that are highly pure PEEK and those that have been reinforced with carbon fiber, glass, or other technical plastics.

PEEK plastic has remarkable durability and is impervious to heat, abrasion, chemicals, heat fatigue, and creep. It has a strength-to-weight ratio that can compete with metals like aluminum, and it is not susceptible to deterioration from chemical or physical stress. In addition to its exceptional biocompatibility, PEEK is also resistant to ultraviolet light, pure radiolucency, and gamma rays and has little to no toxicity. PEEK plastic’s qualities make it suitable for use in a wide variety of engineering contexts, from automobile engine components to medical implants and bearings and chemical and even radiological equipment.

The Definition of PEEK: What Is It?

Semicrystalline polyether ether ketone (PEEK) performance thermoplastic has good resistance to heat, chemicals, wear, and creep and is also very strong. Polyether ether ketone ketone (PEEKK), polyether ketone ketone (PEKK), and polyether ether ketone ketone (PEK) are all examples of the broader class of polymers known as polyaryletherketone (PAEK). PEEK is the most well-known polymer, but there are many more.

What is the PEEK manufacturing process?

Several different organic synthesis techniques can be used to create PEEK, but the most common involves a step-growth polymerization initiated by the dialkylation of bisphenolate salts. To make PEEK, for instance, you need to do a nucleophilic substitution of 4,4′-difluorobenzophenone with hydroquinone in a polar aprotic solvent with a high melting temperature (often diphenyl sulfone) until you have a product that meets your requirements. Despite the lengthy name, this is just a simplified form of the full synthesis, and many businesses employ proprietary techniques to improve particular properties of materials for their target uses. PEEK’s strong temperature and wear resistances relative to other polymers are due, at least in part, to the fact that it is constructed utilizing a rigid aromatic polymer foundation.

Polyether ether ketone (PEEK): What Kinds Are Available?

PEEK comes in both generic and brand-specific varieties; however, there are generally four main grades:

PEEK without filler, PEEK with 30% glass filler
PEEK filled with 30% carbon
You may recognize PEEK as “bearing grade,” “PTFE PEEK,” “carbon fiber-reinforced with graphite PEEK,” “Ketron® HPV,” etc.

The most common type of PEEK plastic is unfilled PEEK, since it may be used for a wide variety of purposes. Unfilled PEEK, in contrast to other grades, is exceptionally pure and contains no reinforcements. The unfilled kind of PEEK has the greatest values for elongation at break, toughness (which should not be confused with strength), and fatigue resistance. PEEK in its unfilled form is FDA-compliant and can be used for both internal and external medical purposes, including recurrent food contact. The most common colors for unfilled PEEK are white, a light brown or tan, and black.

The glass fibers in 30% glass-reinforced PEEK slow the material’s expansion rate and boost its flexural modulus. Consequently, glass-reinforced PEEK is a more robust and rigid alternative to the unfilled grade, making it suitable for use in applications requiring stability (particularly in high-temperature conditions). When joined to other components, glass-reinforced PEEK will wear more quickly than unreinforced PEEK. There are two color options for 30% glass-reinforced PEEK: natural/tan and black.

Carbon fiber impregnated at a 30% level increases the stiffness and compressive strength of 30% carbon-reinforced PEEK while greatly reducing its expansion rate. In addition to being up to 3.5 times more thermally conductive than unfilled PEEK, carbon-filled PEEK is specially designed to withstand wear and carry a high load. Because of its superior characteristics, carbon-reinforced PEEK is a top choice for plastic bearings. Since it incorporates carbon fiber, 30% carbon-reinforced PEEK is only available in a black tint.

PEEK used for bearings is typically 20% PTFE impregnated and carbon fiber bonded with graphite, though this varies by manufacturer. When it comes to mating, friction, load-bearing applications, etc., bearing-grade PEEK has the best wear characteristics thanks to its low coefficient of friction and great machinability. This PEEK grade is called “bearing grade.” because it is so well suited to use in bearings in a wide variety of applications. Grey and black are the most common colors for bearing-grade PEEK.

In What Way Does Polyether Ether Ketone (PEEK) Differ from Other Materials?