Mechanical Performance and Fracture Morphology of Bamboo Cellulose Nanofiber Reinforced PLA Composites for 3D Printing Applications

Resumen

This study reports the development and mechanical characterization of polylactic acid (PLA) reinforced with bamboo cellulose nanofibers (BCNFs) for 3D printing applications. Composite filaments containing 1–5 wt.% BCNFs were fabricated and systematically evaluated for tensile strength, microhardness, impact resistance, and fracture morphology. The results demonstrated a strong dependence of mechanical performance on nanofiber loading. Neat PLA exhibited a tensile strength of 78.21 MPa, which increased progressively with nanofiber addition, reaching a maximum of 112.76 MPa at 3 wt.% BCNF, representing a 44.2% improvement. Similarly, microhardness values improved markedly, with the optimum composition exhibiting a 162.5% increase over neat PLA. Impact resistance followed the same trend, with energy absorption enhanced by 116% at 3 wt.% BCNF. However, at higher loadings (4–5 wt.%), mechanical properties declined due to fiber agglomeration and poor dispersion. SEM analysis of fracture surfaces confirmed these trends, revealing brittle fracture in neat PLA, rough and fibrous morphologies with effective crack deflection at 3 wt.%, and clustered fiber bundles acting as stress concentrators at 5 wt.%. These findings establish 3 wt.% BCNF as the optimum loading for balancing strength, toughness, and hardness, underscoring the potential of bamboo nanocellulose as a sustainable reinforcement for high-performance PLA-based 3D printing filaments.