A Novel 3 <scp>D</scp> ‐Interface Engineering of <scp>WF</scp> / <scp>TPU</scp> Flour Composites: Toward Sustainable and High‐Performance <scp>FDM 3D</scp> Printing Materials

ABSTRACT Wood–plastic composites (WPC), as sustainable materials for additive manufacturing, show broad potential in fused deposition modeling (FDM) 3D printing because of their environmental friendliness and cost‐effectiveness. However, poor interfacial bonding between wood flour (WF) and thermoplastic polyurethane (TPU) severely limits printing quality and mechanical stability. To overcome this challenge, this work presents several interface engineering strategies by introducing modifiers such as polycarbodiimide (PCDI), silane coupling agent (KH550), maleic anhydride (MAH), sodium hydroxide (NaOH), and nano‐aluminum oxide (Al 2 O 3 ). These modifiers aim to improve the interfacial compatibility and overall performance of WF/TPU composites. Multiscale characterization techniques—including scanning electron microscopy (SEM), Fourier‐transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), dynamic rheological testing, and contact angle measurement—were employed to analyze the mechanisms and effects of modification. The results indicated that optimal mechanical properties were achieved at 10 wt% WF content, with significantly enhanced interfacial bonding and melt fluidity. Among all tested modifiers, PCDI and KH550 demonstrated the most pronounced improvement. This study provides a theoretical and practical pathway toward economical, eco‐friendly, and high‐performance WPC materials for 3D printing.