Investigation of Polymer Adhesion of Materials in Multimaterial FFF Process

The increasing availability of multi-material fused filament fabrication (FFF) systems has intensified the need for a systematic understanding of interfacial adhesion between model and support polymers. In this study, the adhesion behavior of commonly used engineering thermoplastics and dedicated support materials was investigated in the context of multimaterial FFF. A comprehensive experimental methodology was developed, including a custom tensile test specimen and fixture specifically designed to quantify interfacial adhesion under controlled conditions. Material combinations based on ABS, ASA, PETG, and carbon-fiber-reinforced PA (PAHT-CF), together with manufacturer-recommended and alternative support materials, were evaluated using uniaxial tensile testing and fracture surface analysis. The results demonstrate that interfacial adhesion strongly depends on material compatibility and processing conditions, and that dedicated support materials generally provide lower adhesion than model–model combinations. However, significant deviations were observed: SUPP PA exhibited unexpectedly high adhesion when paired with PAHT-CF, while SUPP ABS proved to be a more versatile support across multiple model materials, offering a favorable balance between sufficient adhesion during printing and ease of removal. Several material pairs showed negligible adhesion, leading to separation during manufacturing and limiting their practical applicability. Microscopic analysis revealed the coexistence of diffusion-driven bonding, mechanical interlocking, and weak boundary layer effects. The findings highlight that optimal support performance requires neither minimal nor excessive adhesion, and provide experimentally validated guidance for selecting material combinations and process windows in multimaterial FFF.