Key Takeaways & Executive Findings
- •• Adding an optimum amount of PEI to CNT/PEEK nanocomposites reduces molten viscosity by ~50% while increasing strain to failure by 129% and fracture energy by 97%. • The direct wet powder blending method using a vertical injection molding machine ensures uniform dispersion of CNT/PEI powder, improving processability without compromising thermal resistance. • The combination of CNTs and PEI enhances the toughness of PEEK nanocomposites, overcoming the typical trade-off between strength and ductility. • These improvements facilitate the use of PEEK in thermoplastic composites for demanding applications such as aerospace and automotive.
Abstract
Polyether ether ketone (PEEK) has good mechanical properties. However, its high viscosity when molten limits its use because it is hard to process. PEEK nanocomposites containing both carbon nanotubes (CNTs) and polyether imide (PEI) were prepared by a direct wet powder blending method using a vertical injection molding machine. The addition of an optimum amount of PEI lowered the viscosity of the molten PEEK by approximately 50% while producing an increase in the toughness of the nanocomposites, whose strain to failure increased by 129%, and fracture energy increased by 97%. The uniformly dispersed CNT/PEI powder reduced the processing difficulty of PEEK nanocomposites without affecting the thermal resistance. This improvement of the strength and viscosity of PEEK facilitate its use in the preparation of thermoplastic composites.
1. Introduction
Polyether ether ketone (PEEK) has excellent mechanical properties, thermal stability, abrasion resistance, and solvent resistance compared with other polymers. It has been widely used in aviation, automotive industry, offshore technology, and biomedical industry. PEEK is also widely used in fiber-reinforced polymers and 3D-printed composites[1–4]. These applications require PEEK to have low viscosity and high toughness. However, PEEK has high melting temperature and viscosity[5], resulting in difficult processing.
To address this difficulty, polymer blends can be used in the processing of PEEK[6]. Polyether imide (PEI) is an amorphous thermoplastic resin with a high glass transition temperature (Tg). It is highly hydrophobic, commercially available, and chemically compatible with PEEK, making it miscible with PEEK at any mixing ratio[7–8]. Its viscosity can be significantly reduced by incorporating PEI[9]. However, the viscosity reduction is limited, and the strength decreases with the addition of PEI[10].
On the other hand, researchers now are committed to further improve the performance of a certain aspect of PEEK by adding nanofillers[11–13], such as carbon nanotubes (CNTs)[14–17] and graphene[18–20]. As an excellent nanoscale reinforcement, CNTs have excellent strength, rigidity, electrical and thermal conductivity, making them an excellent nanoscale reinforcement[21–23]. Zhang[24] reviewed the studies on the tensile properties of CNT/PEEK. The tensile strength of CNT/PEEK can reach 121 MPa at a CNT content of 15%[25]. The addition of CNTs can result in a significant improvement in the mechanical properties and antifriction properties of PEEK[24].
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SONG Jiu-peng, ZHAO Yan, LI Xue-kuan, XIONG Shu, LI Shuang, WANG Kai (2025). Increasing the toughness while reducing the viscosity of carbon nanotube/polyether imide/polyether ether ketone nanocomposites. SinoTechIntel Verified Research. https://doi.org/10.1016/S1872-5805(NCM2024-39-04-10)
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Frequently Asked Questions
What is the main challenge of processing PEEK?
PEEK has high melting temperature and high viscosity when molten, making it difficult to process.
How does adding PEI affect the viscosity of PEEK?
Adding an optimum amount of PEI can lower the viscosity of molten PEEK by approximately 50%.
What are the improvements in toughness observed in the study?
The strain to failure increased by 129% and fracture energy increased by 97%.
What method was used to prepare the nanocomposites?
A direct wet powder blending method using a vertical injection molding machine was used.
Does the addition of CNT/PEI affect thermal resistance?
No, the thermal resistance of the nanocomposites is not affected.
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