Polymer materials are increasingly widely used in high-fire-risk applications, such as aviation interior components. This study aimed to compare the tensile, thermal, and flame-retardant properties of test samples made from ultra-performance materials, polyetherimide (PEI) and polyetherketoneketone (PEKK), using the fused filament fabrication process (FFF). The tensile tests were performed for these materials at different raster angles (0, 45, and 90°). The thermomechanical tests were done in the axial, perpendicular, and through-thickness directions to the extruded filaments. The impact of printing parameters on the flame retardancy of 3D-printed samples was investigated in vertical burn tests with varying specimen thicknesses and printing directions. Experimentally, it was testified that PEKK had better isotropic behaviour than PEI for mechanical performance, thermal expansion, and fire-resistant properties, which are essential in fabricating intricately shaped products.

Despite the impressive properties of additively manufactured products, their inherent anisotropy is a crucial challenge for polymeric parts made via fused filament fabrication (FFF). This study compared the tensile, thermophysical, smoke density, and toxicity characteristics of Ultem 9085 (a blend of polyetherimide and polycarbonate) for samples printed in various orientations (X, Y, and Z). The results revealed that mechanical properties, such as elastic modulus and tensile strength, significantly differed from the Z printing orientation, particularly in the X and Y printing layer orientations. Thermomechanical analysis revealed that Ultem 9085 had high anisotropic effects in the coefficient of thermal expansion, indicating superior thermal properties along the printing orientation. The smoke density and toxicity test results proved that Ultem 9085 complies with aviation safety standards. Smoke density tests showed that all samples, regardless of print orientation or thickness, stayed well below the regulatory limit, making them suitable for aircraft interiors.

Materials applied in interior and non-structural aircraft components are required to satisfy rigorous safety and performance criteria, especially with respect to flame retardancy and wear resistance. Ultem 9085, a high-performance polyetherimide thermoplastic, is extensively used in aerospace applications owing to its advantageous strength-to-weight ratio and compliance with flame, smoke, and toxicity (FST) requirements. Nevertheless, the application of surface coatings, including paints, may modify their fire-retardant and tribological performance, with potential implications for service behavior and regulatory compliance. This work provides new insight into the behavior of painted Ultem 9085 components under fire exposure and frictional loading, addressing the critical need to determine whether surface finishing affects the material’s inherent performance advantages. Thus, the effects of different paint coatings on the fire-retardant and tribological properties of Ultem 9085 are investigated. Test specimens were manufactured using a Stratasys F900 system with 100% infill density and geometries adapted for standard vertical burn and heat release tests. Fire performance testing, including vertical burn, smoke and toxicity, and heat release rate, was performed in accordance with CS/FAR 25 Appendix F and AITM 3-0005 requirements. Tribological behavior was assessed using a ball-on-flat tribometer under dry-sliding conditions, while surface texture was analyzed using 3D profilometry. Seven polymer–coating composites were examined. It was experimentally confirmed that all coatings reduced vertical burn length but increased peak heat release rate and smoke density relative to unmodified Ultem 9085. Tribological results varied significantly, highlighting the critical role of paint selection in achieving optimal fire safety and wear resistance.