polyether ether ketone chemical formula

Polyether Ether Ketone Formula Unveiled

Welcome to our article on Polyether Ether Ketone (PEEK)! Today, we will delve into the chemical formula, structure, properties, applications, and synthesis of this remarkable polymer. PEEK has gained significant recognition in various industries for its exceptional performance in extreme conditions. Let’s explore the world of PEEK together and discover its endless possibilities.

Grades of Polyether Ether Ketone (PEEK)

PEEK is a versatile polymer that comes in various grades, each with specific properties and applications. Understanding the different grades of PEEK is essential when choosing the right material for your project. Let’s explore the four primary PEEK grades:

  1. Unfilled PEEK: This is the general-purpose grade of PEEK, highly pure and unreinforced. It offers the highest elongation, toughness, and fatigue resistance among all PEEK grades. Unfilled PEEK is FDA-approved for food contact and medical applications.
  2. 30% glass-filled PEEK: This grade is reinforced with 30% glass fibers, which significantly increases its stiffness and flexural modulus. It is stronger and stiffer than unfilled PEEK, making it ideal for structural applications.
  3. 30% carbon-filled PEEK: Reinforced with 30% carbon fibers, this grade of PEEK offers enhanced stiffness, compressive strength, and thermal conductivity. It is particularly suitable for wear resistance and load-carrying applications.
  4. Bearing grade PEEK: This grade is typically impregnated with PTFE and reinforced with graphite fibers. It provides low friction, high machinability, and exceptional wear characteristics, making it perfect for bearing applications.

Table: Comparison of Different Grades of PEEK

Grade Properties Applications
Unfilled PEEK High elongation, toughness, and fatigue resistance Food contact, medical implants, general purpose
30% glass-filled PEEK Increased stiffness and flexural modulus Structural applications, aerospace components
30% carbon-filled PEEK Enhanced stiffness, compressive strength, and thermal conductivity Wear resistance, load-carrying applications
Bearing grade PEEK Low friction, high machinability, excellent wear characteristics Bearing applications, high-performance components

Properties and Applications of Polyether Ether Ketone (PEEK)

PEEK, also known as Polyether Ether Ketone, possesses a wide range of exceptional properties that make it a highly sought-after material in various industries. These properties include:

  • High-temperature performance
  • Wear and chemical resistance
  • Stability in water-bound environments
  • Excellent strength and toughness

Due to its remarkable properties, PEEK finds applications in diverse industries and sectors. Some notable applications of PEEK include:

Industry/Application PEEK Application
Automotive Automobile components, pump components
Aerospace Aerospace components
Electronics Fasteners for electronic devices
Medical Medical implants, surgical devices, FDA-compliant food contact equipment
Industrial Ball bearings, cable insulation, injection molded parts
Semiconductor Semiconductor manufacturing equipment

One of the significant advantages of PEEK lies in its suitability for plastic injection molding. This process allows the creation of high-performance, low-weight parts with complex geometries. However, there are also some challenges associated with PEEK in plastic injection molding, such as:

  • Challenging processing parameters
  • Anisotropic shrinking during cooling
  • Need for proper drying to avoid molding defects

It is important to note that PEEK is FDA and medical device-approved, ensuring its safety for repeated food exposure, internal and external medical implants, and other applications that require biocompatibility.

Besides these applications, PEEK is also known for its good electrical insulation properties, low permeability, and resistance to radiation, heat, and harsh chemicals.

Note: The image above visually represents the various properties of PEEK.

Processing and Synthesis of Polyether Ether Ketone (PEEK)

Polyether Ether Ketone (PEEK) can be processed using various conventional methods, including injection molding, extrusion, compression molding, and 3D printing. These processing techniques play a crucial role in transforming PEEK into functional and complex components for a wide range of applications.

When processing PEEK, it is important to consider specific guidelines and control the processing conditions to achieve the desired crystallinity and mechanical properties. This ensures the production of high-quality PEEK parts with optimal performance.

Injection Molding

Injection molding is a common method used to process PEEK. It involves heating the PEEK resin to a melt state and injecting it into a mold cavity to form the desired shape. Injection molding is suitable for producing small parts with tight dimensional tolerances.

The injection molding process for PEEK typically involves the following:

  1. Heating the PEEK resin to a temperature of 350-400°C to achieve a molten state.
  2. Injecting the molten PEEK into a mold cavity at high pressure.
  3. Cooling the mold to solidify the PEEK and remove the part from the mold.

During the injection molding process, it is essential to maintain a mold temperature of 160-190°C to control the cooling rate and ensure dimensional stability. However, post-crystallization at higher temperatures, around 200°C, can be performed to enhance the stability of the molded parts.


Extrusion is another commonly used method for processing PEEK. It involves forcing the molten PEEK resin through a die to create continuous shapes such as rods, tubes, or sheets.

The extrusion process for PEEK can result in transparent or opaque materials, depending on the cooling temperature applied. It also allows for the production of highly crystalline PEEK, which exhibits enhanced mechanical properties. Additionally, extrusion can be used to produce oriented or bioriented films, expanding the application possibilities of PEEK.

3D Printing

Advancements in additive manufacturing technology have made it possible to 3D print PEEK. Fused Deposition Modeling (FDM) is a common method used for 3D printing PEEK filaments.

The 3D printing process for PEEK involves the following steps:

  1. Preheating the nozzle to a temperature of 360-400°C to maintain PEEK in a molten state.
  2. Heating the build platform to a temperature of 120°C to ensure proper adhesion and layer bonding.
  3. Layer-by-layer deposition of molten PEEK to create the desired 3D printed object.

3D printing with PEEK opens up new possibilities for complex part geometries and customization. It has become a valuable tool in industries where rapid prototyping and low-volume production are required.

PEEK 3D Printing

PEEK Synthesis and Polymerization

The synthesis of PEEK polymers involves step-growth polymerization by the dialkylation of bisphenolate salts. This reaction is carried out using 4,4′-difluorobenzophenone or 1,4-bis(4-fluorobenzoyl)benzene with hydroquinone in the presence of alkali carbonates.

During polymerization, the bisphenolate salts react with the carbonyl groups, forming a polymer backbone with repeating units of ether and ketone linkages. This results in the formation of a highly stable and robust PEEK polymer structure.

Molding and Extrusion Guidelines for PEEK

When working with PEEK, it is essential to follow specific processing guidelines to achieve optimal results. Here are some recommended parameters for molding and extrusion:

Processing Method Temperature Range (°C) Comments
Injection Molding 350-400 Ensure proper melt temperature for PEEK resin.
Mold Temperature 160-190 Control cooling rate for dimensional stability.
Post-Crystallization 200 Enhance dimensional stability.
Extrusion 350-400 Keep proper extrusion temperature for PEEK resin.
Cooling Temperature Varies Affect material transparency and crystallinity.
3D Printing Nozzle: 360-400
Build Platform: 120
Ensure proper nozzle and build platform temperatures.

Drying PEEK for Processing

Prior to processing PEEK, it is crucial to remove any moisture to avoid molding defects and ensure optimal performance. Drying can be done at temperatures of 150°C for 3 hours or 180°C for 2 hours.


Polyether Ether Ketone (PEEK) is a highly versatile polymer with a wide range of properties and applications. Its excellent mechanical strength, chemical resistance, high-temperature performance, and biocompatibility make it a preferred choice in demanding industries such as aerospace, automotive, and medical.

PEEK can be processed using various methods, including injection molding, extrusion, and 3D printing, allowing for the creation of complex shapes and structures. However, it is important to ensure specific processing conditions and meticulous monitoring to achieve optimal results.

While PEEK offers numerous advantages, it is essential to consider some limitations. PEEK can be relatively expensive compared to other polymers, and it may exhibit sensitivity to certain acids, chemicals, and UV light. Additionally, its limited recyclability should be taken into account.

Despite these limitations, PEEK remains a highly valuable material in advanced material applications. It continues to push the boundaries of engineering and innovation, demonstrating its potential for future developments in various industries.


What is the chemical formula of Polyether Ether Ketone (PEEK)?

The chemical formula of PEEK is C19H14O3.

What are the different grades of PEEK available?

The four primary grades of PEEK are unfilled PEEK, 30% glass-filled PEEK, 30% carbon-filled PEEK, and bearing grade PEEK.

What are the properties and applications of PEEK?

PEEK exhibits excellent mechanical strength, chemical resistance, high-temperature performance, and biocompatibility, making it suitable for a wide range of applications such as aerospace, automotive, medical, and more.

How is PEEK processed and synthesized?

PEEK can be processed using methods such as injection molding, extrusion, and 3D printing. It is synthesized through step-growth polymerization by the dialkylation of bisphenolate salts.

What are the conclusions about PEEK?

PEEK is a highly versatile polymer with a wide range of properties and applications. Despite its advantages, it has some limitations and continues to be used in advanced material applications.

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