Mechanical compressive properties of TPU 3D printed with various parameters

Shape memory polymer (SMP) is a material that has the ability to recover its original shape from a temporary (deformed) shape by applying external stimuli. The smart scaffold based on SMP is used to enhance delivery, load bearing, and tissue defect filling. Therefore, specimens with the structure of the face-centered cubic were produced under various printing conditions to characterize their effects on the mechanical properties. Fused deposition modeling is utilized to construct the specimens of shape memory thermoplastic polyurethane (MM-3520). Printing parameters with different levels were used in specimen fabrication, including layer thicknesses of 0.1, 0.2, and 0.3 mm, printing temperatures of 210, 220, and 230 ° C, and printing speeds of 20, 30, and 40 mm/sec. We performed the microstructural analysis under a microscope to examine the impact of printing factors on lattice structures. Then there is the compression test, which evaluates mechanical properties such as linear elastic stiffness, collapse stress, plateau stiffness, and densification stress. Analyzing the microstructure of the printed specimens exhibits that the specimens with the highest printing temperature, the lowest printing speed, and a thinner printing layer have better layer adhesion and lower porosities. As well, figures and main effect plots revealed that the specimens printed with a layer height of 0.1mm, a printing temperature of 230 ° C, and a printing speed of 20 mm/s had compressive strengths of 0.6129±0.062, 0.6018±0.106, and 0.6082±0.078 MPa, respectively. These are the highest results in terms of strength compared to other levels of parameters.