Impact of Raster Angle on 3D Printing of Poly(Lactic Acid)/Thermoplastic Polyurethane Blends: Effects on Mechanical and Shape Memory Properties

Abstract In this study, a 60:40 blend of poly(lactic acid) and thermoplastic polyurethane (PLA/TPU) is fabricated using fused material extrusion. The morphological, thermal, mechanical and thermoresponsive cyclic shape memory effect (SME) characteristics of 3D‐printed specimens at various raster angles are investigated. This work introduces the innovative utilization of TPU's fibrillar alignment within a PLA matrix to achieve enhanced mechanical anisotropy and consistent shape memory performance. Morphological analysis reveals excellent printability, with the immiscible TPU phase forming submicron‐diameter fibrils (≈0.78 ± µm) within the PLA matrix, leading to significant improvements in toughness and elongation at break when aligned with the printing direction and the load. Tensile test demonstrates anisotropy, with 0° raster specimens achieving a UTS of 16.1 ± 0.2 MPa and elongation at 305.5 ± 71.9%, compared to 4.5 ± 0.6 MPa and 10.8 ± 1.5% at 90°. Notably, despite the mechanical anisotropy, shape fixity ratios exceeded 95% and recovery ratios between 91 and 95% were achieved across all raster angles, demonstrating robustness in thermomechanical properties. These findings offer valuable insights into the relationship between morphology, mechanical characteristics, and shape memory behavior of PLA/TPU blends fabricated using fused material extrusion, positioning the material as a strong candidate for biomedical applications requiring precise shape recovery performance.