Table of Contents
PEEK (polyether ether ketone) is one of the world’s most efficient high-performance plastics and impresses with its exceptional combination of mechanical, thermal and chemical resistance. This material has proven itself in demanding industries such as the aerospacemedical technology and in the automotive and electronics industries. Its special properties make PEEK a catalyst for the development of new additive manufacturing methods and a central platform in high-performance polymer research.
Structural principles and crystallinity
The outstanding property profile of PEEK is largely based on its semi-crystalline structure. The crystallite fractions form ordered, densely packed areas in the amorphous polymer matrix, which leads to high mechanical strength and rigidity even at elevated temperatures, improved chemical resistance and low water absorption. The degree of crystallinity can be specifically modulated by process parameters such as cooling rate or heat treatment, whereby higher crystallinityhigher crystallinity strengthens the strength and barrier properties, while amorphous areas provide flexibility and impact strength.
Thermal properties and resistance
A key unique selling point of PEEK is its high melting point of around 343 °C, which is significantly higher than that of conventional thermoplastics. This enables permanent use at temperatures of up to 250-260 °C with short-term loads beyond this, thermal sterilization and steam autoclaving as well as use in reaction-intensive production processes.
The glass transition temperature (Tg) is around 143 °C, whereby the material becomes increasingly flexible above this temperature and remains hard and dimensionally stable below. PEEK remains dimensionally stable without significant loss of stress or thermal degradation even when subjected to continuous loads of up to 260 °C.
Chemical and mechanical robustness
PEEK is characterized by excellent resistance in all areas: chemically resistant to acids, bases, organic solvents and strong oxidizing agents, UV-stable with high ageing resistance, mechanically robust with high fatigue resistance and low notch sensitivity as well as hydrolysis-resistant to hot water and steam. These properties are essential in aggressive application scenarios such as pump, valve or sealing components for chemical processes, offshore plants or high-temperature furnace components.
Variety and specialization
PEEK is available in numerous variants: standard PEEK for general applications, glass fiber and carbon fiber reinforced grades with increased tensile strength and stiffness, specialty copolymers of the PAEK family with modified properties as well as blends and composites with ceramic, metallic or other polymer additives for specific requirements such as electrical conductivity or X-ray opacity.
This diversity of variants enables targeted adaptation for individualized applications – from medical technology implants and sensor housings to highly stressed structural components in aviation.
Additive manufacturing and new possibilities
In recent times, additive manufacturing processes, in particular 3D printing with PEEK, have dramatically expanded the application possibilities. 3D-printed PEEK implants open up new horizons for patient-specific medical technology thanks to complex geometries and controlled porosity directly at the point of care. Studies show that “the modulus of elasticity of crystalline samples increases by up to 20% compared to amorphous structures” (Von M Mrówka et al., 2021).
Biomedical innovations
The primary disadvantage of PEEK in medical technology – its bioinertness – is addressed by innovative surface modifications. Plasma treatment, lasers, chemical functionalization or the embedding of bioactive fillers can significantly improve the biological interactions. These new composites promote osteointegration and can impart antibacterial properties (Nature, 2024).
Sustainability and future prospects
In terms of sustainability, PEEK is characterized by its long service life, recycling options and reduced maintenance costs due to its robustness. This is particularly relevant in industries that place strict regulatory requirements on materials for media contact, biocompatibility and recycling.
Conclusion
PEEK is more than just a high-performance all-rounder – it is an innovation driver for extreme requirements. The combination of molecular diversity, functional adaptability and industrial relevance makes PEEK the central platform in high-performance polymer research. Its classification as a versatile high-performance polymer is based on its ability to balance properties in a targeted manner and optimize them for specific applications, enabling individual solutions for laboratory research, industrial development and highly safety-relevant operation.
List of sources
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From M Mrówka, M., Machoczek, T., Jurczyk, K., Joszko, K., Pankalla, M., Gzik, M., & Wolański, W. (2021). Mechanical, Chemical, and Processing Properties of PEEK Specimens Made by 3D Printing. Materials, 14(11), 2717.
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