Additive manufacturing of natural fiber reinforced polymer composites - A review

The integration of natural fibers into 3D-printed polymer composites has gained significant attention due to the growing demand for sustainable and high-performance materials. This review comprehensively examines the material selection, processing methods, property enhancement techniques, 3D printability, challenges, and future prospects of natural fiber-reinforced polymer composites in additive manufacturing or 3D printing of polymer composites. Natural fibers, categorized into plant-based (bast, leaf, grass, seed/fruit, and wood fibers) and animal-based (silk, keratin, and secreted protein/shell-based biofillers), offer biodegradability, renewability, and enhanced mechanical properties, making them promising reinforcements for polymer matrices such as polylactic acid (PLA) and polycaprolactone (PCL). However, challenges such as fiber hydrophilicity, thermal degradation, and poor interfacial bonding necessitate surface treatments, fiber modifications, and process optimizations to improve printability and composite performance. While additive manufacturing techniques, particularly fused deposition modeling (FDM) and stereolithography (SLA), enable the fabrication of complex geometries with reduced material waste, factors like nozzle clogging, fiber alignment, and anisotropic mechanical properties remain key limitations. Future research should focus on novel fiber-polymer combinations, advanced printing techniques, life cycle analysis, and expanding applications into fields such as construction. By addressing these challenges, 3D printing of natural fiber-reinforced polymer composites can advance the area of sustainable manufacturing of biocomposites while maintaining structural integrity and functional performance.