In-situ synergistic enhancement of interlayer bonding strength and flame retardancy in 3D printed CF/PEEK composites via Nano-POSS under elevated chamber temperature

3D printed carbon fiber reinforced polyether ether ketone (CF/PEEK) composites have the potential for a wide range of applications, including in the electrical and electronic appliances, automotive, and aerospace industries. Understanding how to enhance the interlayer bonding strength and the combustion behavior of carbon fiber composites are prerequisites for these applications. In this study, a high-performance anti-static CF/PEEK ESD composite for material extrusion (ME) 3D printing was prepared using recycled carbon fibers (rCF), carbon nanotubes (CNTs), and polyhedral oligomeric silsesquioxane (T₇-POSS). The interlayer adhesion and combustion of 3D printed CF/PEEK ESD at a high chamber temperature (255 °C) were enhanced in situ by the combined action of gas-phase and condensed-phase materials obtained by pyrolyzing POSS and aligned CF. The interlayer adhesion of CF/PEEK ESD reaches 46 MPa, and its time to ignition (TTI) is extended to 606 s, while the peak heat release rate (pHRR) is as low as 93 kW/m². Furthermore, during the printing process, POSS decomposes to produce substances with a large number of benzene rings and -OH groups. These substances are π-π conjugated and hydrogen-bonded to the PEEK molecular chain, promoting the ordering of the PEEK molecular chains and enhancing the interlayer bonding and combustion properties. This meets the needs of the aerospace and electrical and electronic industries for materials that are high-strength, flame-retardant, and anti-static. It also provides technical support for the development of high-performance 3D printing materials.