Mechanical dependence of 3D-printed thermoplastic polyurethane reinforced with minor continuous carbon fibres

Mechanical dependence of 3D-printed thermoplastic polyurethane (TPU) reinforced with continuous carbon fibres (CCFs) on the selected printing conditions was investigated. The melt-extrusion-based 3D-printing (ME3DP) method was employed to fabricate specimens, of which the dependence of tensile, flexural and cryo-impact properties on layer thickness, printing speed and layer number was evaluated. Results showed that the printed TPU reinforced with raw CCFs revealed an over five-fold increase in tensile yield stress with the occurrence of necking phenomenon whereas those reinforced with preimpregnated CCFs (PCCFs) displayed brittle fracture which was also confirmed by the impact testing. The flexural strength and modulus of the printed CCFs/TPU were greatly raised over that of TPU and the PCCFs provided a much more enhancement. Both the increased yield stress and flexural strength implied an improved capacity for dynamic load bearing. Finally, the structure–property relationship was established via interface microstructure detection and simulation.