Sustainable 3D Printing of PLA / PBAT /Bamboo Fiber Bio‐Composites: Interfacial Compatibility Regulation Through In Situ Bio‐Based Epoxidized Agent Polymerization

ABSTRACT This study aims to enhance the mechanical properties of fused deposition modeling (FDM) 3D‐printed poly(lactic acid) (PLA) filaments via a dual modification approach combining bamboo fiber (BF) reinforcement and poly(butylene adipate‐co‐terephthalate) (PBAT) toughening, along with a bio‐based interfacial engineering method using in situ graft‐polymerized epoxidized soybean oil (ESO) and cardanol glycidyl ether (NC514). This strategy concurrently mitigates PLA‐PBAT immiscibility and poor BF‐matrix adhesion—key challenges in FDM‐printable biocomposites. Initiated by BF 3 NH 2 Et, ESO and NC514 were self‐polymerized into Poly(ESO) and Poly(NC514), grafted onto BF to form EBF and NBF, and then melt‐blended with PLA/PBAT into biocomposites. Poly(NC514) improves stress transfer and load distribution via synergistic chemical bonding (covalent and π–π interactions) and physical entanglement, suppressing interfacial debonding and phase separation. With 30 wt% NBF‐1 (BF modified with 4 wt% Poly(NC514)), FDM‐printed PLA/PBAT/NBF‐1 biocomposites outperform commercial PLA filaments: tensile modulus rises by 120% (7.7 vs. 3.5 GPa), elongation at break by 194% (15.3% vs. 5.2%), water absorption drops by 53% (0.52% vs. 1.10%), and Vicat softening temperature increases by 26% (79.5°C vs. 62.9°C). These results confirm the effectiveness of the interfacial modification strategy for producing high‐performance, 3D‐printable biocomposites.