Investigation of Mechanical Properties in Layered Multi‐Material <scp>3D</scp> Printing Using Commercial Filaments: Direct Stacking of <scp>ABS</scp> , <scp>PA</scp> , and Compatibilizing Layers

ABSTRACT Fused filament fabrication (FFF) technology has rapidly progressed in software and equipment, driven by increasing demand across industries and households. However, the development of compatible and high‐performance materials has lagged, limiting the mechanical integrity and design flexibility of printed components. To address this issue, this study investigates the interfacial bonding behavior of multi‐material structures composed of acrylonitrile butadiene styrene (ABS) and polyamide (PA), two polymers that are chemically incompatible. To enhance interfacial adhesion, three commonly used thermoplastic filaments were employed as intermediate compatibilizing layers. Mechanical characterization was performed through tensile and interlaminar shear strength tests to evaluate bonding performance. All compatibilizing layers improved adhesion between ABS and PA, yielding up to 32% higher tensile strength and 43% higher interlaminar shear strength compared to direct stacking. Fractographic observations confirmed these results by revealing distinct failure patterns and improved interfacial continuity. Overall, the findings demonstrate a practical method for achieving strong adhesion between incompatible polymers without surface treatments or adhesives, offering guidance for the design of hybrid structures and expanding the potential of the technology.