Fabrication and characteristics of flexible thermoplastic polyurethane filament for fused deposition modeling three‐dimensional printing

Abstract In the era of artificial intelligence (AI), materials with soft and strong properties are becoming increasingly important. Various three‐dimensional (3D) fused deposition modeling (FDM) filaments have been developed as soft actuator materials. In the present study, a soft actuator‐grade thermoplastic polyurethane (TPU) was developed and then processed into a filament for FDM 3D printers during a melt‐extrusion process using commercial (65, 75, 80, and 85 Shore A) pellets. Rheological, chemical, thermal, and mechanical properties of the manufactured TPU filaments were characterized. Auxetic re‐entrant TPU samples were then printed with the manufactured filament. Results showed that the 75 Shore A pellet was the most suitable for auxetic re‐entrant FDM 3D printing.