This study has investigated the physical properties of 3D-printable shape memory thermoplastic polyurethane (SMTPU) filament and its 3D-printed sinusoidal pattern obtained by fused deposition modeling (FDM) technology. To investigate 3D filaments, thermoplastic polyurethane (TPU) and SMTPU filament were examined by conducting infrared spectroscopy, x-ray diffraction (XRD), dynamic mechanical thermal analysis (DMTA), differential scanning calorimetry (DSC) and a tensile test. Then, to examine the 3D-printed sinusoidal samples, a sinusoidal pattern was developed and 3D-printed. Those samples went through a three-step heating process: (a) untreated state; (b) 5 min heating at 70°C, cooling for 30 min at room temperature; and (c) a repeat of step 2. The results obtained by the three different heating processes of the 3D-printed sinusoidal samples were examined by XRD, DMTA, DSC and the tensile test to obtain the effect of heating or annealing on the structural and mechanical properties. The results show significant changes in structure, crystallinity and thermal and mechanical properties of SMTPU 3D-printed samples due to the heating steps. XRD showed the increase in crystallinity with heating. In DMTA, storage modulus, loss modulus and the tan σ peak position also changed for various heating steps. The DSC result showed that the Tg for different steps of the SMTPU 3D-printed sample remained almost the same at around 51°C. The tensile property of the TPU 3D-printed sinusoidal sample decreased in terms of both load and elongation with increased heating processes, while for the SMTPU 3D-printed sinusoidal sample, the load decreased but elongation increased about 2.5 times.
Shape-Memory-Recovery Characteristics of Microcellular Foamed Thermoplastic Polyurethane
