Shear strength at the interface between polylactic-acid and thermoplastic polyurethane layers processed with multi-material additive manufacturing

Multi-material additive manufacturing for joining two dissimilar polymers, such as the rigid polylactic-acid and the flexible thermoplastic polyurethane, has gained attention of researchers. However, the interaction between these two printed materials remains poorly understood. This study evaluated the shear strength at the interface between PLA and TPU materials, joined through fused filament fabrication, using peel-off testing following ASTM 3163-01 standard. The results revealed low shear strength at the interface of these two printed materials, indicating that their bonding mechanism was primarily driven by surface contact. Furthermore, the applied raster angles significantly influenced the measured shear strength of the printed materials. © 2025 Society of Manufacturing Engineers (SME)