Acrylonitrile Butadiene Styrene/Thermoplastic Polyurethane Blends for Material Extrusion Three-Dimensional Printing: Effects of Blend Composition on Printability and Properties.

Blend filaments of acrylonitrile butadiene styrene (ABS) and thermoplastic polyurethane (TPU) were prepared at different weight ratios, i.e., 100:0, 70:30, 50:50, 30:70, and 0:100, for FDM printing; the prepared filaments, with an average diameter of 2.77 ± 0.19 mm, were encoded as A100, A70T30, A50T50, A30T70, and T100, respectively. The properties and printability of the filaments were thoroughly investigated. The blend composition, as well as the printing parameters, were optimized to obtain the FDM-printed objects with a well-defined surface structure and minimized warpages. The glass transition temperatures of ABS and TPU in the blends were not much altered from those of the parent filaments, whereas the thermal degradation characteristics of the blend filaments still fell between those of the neat filaments. The fractured surfaces of the filaments, observed by SEM, appeared smoother when higher amounts of TPU integrated; the smoothest surface of the ABS-based filament was found in A30T70, indicating the well-compatible blend characteristic. This was also confirmed by its rheological behavior examined by a parallel plate rheometer at 225 °C. Not only was the printability of the filaments improved, but also the warpages of the 3D-printed specimens were decreased when increasing amount of TPU was incorporated into the filaments. Among the printed objects, the A30T70 specimen exhibited the evenest surface morphology with the lowest surface roughness value of 32.9 ± 13.2 nm and the most uniform and consistent linear printing structure when being fabricated at the nozzle temperature of 225 °C and the printing bed temperature of 60 °C. However, the incorporation of TPU into the filaments markedly cut down both strength and modulus values of the fabricated materials up to about half but assisted the printed articles to absorb more energy, demonstrating that this polymer served as a good and effective toughener for ABS.