Despite the widespread use of fused filament fabrication (FFF) (an extrusion-based additive manufacturing process) to manufacture end-use parts for the aerospace industry, limited materials are available within this process that can be used for structural applications in the harsh space environment. Currently available high-performance polymers need to be improved by incorporating additives within the polymer matrix to achieve multi-functional properties. Additives such as graphene, graphene oxide, carbon nanotubes and boron carbide are known to improve mechanical and thermal properties and radiation shielding. This study aims to understand if these additives can be successfully incorporated into PEKK matrix to manufacture printable filaments for FFF. Graphene, graphene oxide (GO) and boron carbide (B₄C) were compatibilised with PEKK matrix, and their mechanical, thermal and rheological properties were analysed and compared with commercially available carbon fibre and carbon nanotube-reinforced PEKK where appropriate. As rheological properties of the formulations confirmed that they were printable, filaments for FFF were then manufactured. Graphene–PEKK was the most printable filament followed by GO–PEKK while B₄C–PEKK was not printable. TEM images of filament cross-section showed good dispersion of graphene and graphene oxide, while boron carbide formed large agglomerates; B₄C also presented feeding issues due to its hardness which affected its printability. Dispersion of the additives was also confirmed by studying their X-ray diffraction (XRD) patterns, and chemical structures were assessed using FT-IR spectroscopy. Finally, parts were printed using selected composite filaments, and their porosity and surface roughness were compared with neat PEKK and commercial CNT-reinforced PEKK to develop an understanding of metrology and bulk material properties of the composites.

The growing scarcity of natural renewable resources has accelerated interest in producing nanomaterials from waste streams. Nanomaterials offer exceptional reinforcement capabilities for advanced composites, driving the need for sustainable and scalable production routes. While prior reviews have broadly examined nanomaterial synthesis from biomass or industrial residues, they often overlook textile waste as a strategic feedstock. This review uniquely focuses on the upcycling of textile waste—one of the most abundant yet underutilized waste streams—into high-value nanomaterials, thereby advancing circular economy principles. Unlike earlier studies that primarily discuss energy recovery or generic recycling, this work systematically explores mechanical, chemical, and thermal conversion routes tailored for textiles, leading to the production of cellulose nanofibers, cellulose nanocrystals, and carbon nanoparticles, which represent a significant class of biodegradable nanomaterials. Furthermore, a comprehensive analysis of the physicochemical properties of the nanomaterials and their emerging applications in water purification and environmental remediation is provided. An alternative pathway for nanomaterial synthesis from waste rather than renewable sources, providing information on the effective extraction of nanomaterials from mixed fiber compositions and dye residues present in textile waste, is also highlighted. By addressing current challenges and outlining future research directions, this review establishes a roadmap for sustainable textile waste valorization, marking a critical step toward eco-friendly nanomaterial production.