Abstract
Among the hybrid manufacturing techniques, hybrid injection molding is a cutting-edge manufacturing strategy that combines the benefits of additive manufacturing (AM) and conventional injection molding (IM), enabling the production of parts with complex internal structures and functionalities. To take full advantage of the hybrid injection molding process, understanding interfacial bonding between materials with different degrees of stiffness is critical, as it can significantly affect the overall structural and mechanical integrity.
In this study, the hybrid injection molding process is used to produce nano-reinforced hybrid structures with two layers of acrylonitrile butadiene styrene (ABS) and carbon nanotube polyurethane nanocomposite (TPU/CNT). ABS substrates were manufactured by fusion filament fabrication (FFF) and then over-molded with TPU/CNT nanocomposite to add functionality. For comparison, ABS-TPU/CNT structures were also produced by conventional over-molding and FFF. The interface properties (interface bonding and adhesion mechanisms) of the ABS-TPU/CNT specimens were investigated by lap-shear tensile test. It was found that the interface of the hybrid ABS-TPU specimens is as strong as that of those obtained by over-molding but about 35% higher than the 3D-printed interface. On the other hand, the hybrid ABS-TPU specimens with 5 wt.% CNTs exhibit electrical conductivity in the semi-conduction range, comparable with that of the over-molded specimens and about one order of magnitude lower than that of the 3D-printed specimens. This work provides guidance for assessing the potential of using hybrid injection molding technology (e.g., 3D printing and injection molding) for engineering applications.
