Mechanical Behavior of 3D PolyJet-Printed Nylon 66/Photopolymer Textile Laminates

Large-area three-dimensional polyjet printing (3DPP) of continuous photopolymer laminates directly onto knitted fabrics provides a potential route toward technical textile applications beyond localized decorative features. This study investigated acrylic photosensitive resin (APR) laminates measuring 330 × 432 mm deposited onto a Nylon 66 interlock-knitted fabric. 12- and 20-layer laminates were produced in one-sided and two-sided configurations, and their morphology and tensile behavior were evaluated in the wale and course directions before and after 20 h of accelerated xenon-arc weathering. Scanning electron microscopy (SEM) showed a continuous external APR layer with localized resin entry into inter-yarn and inter-filament spaces, indicating a form-fitting physical connection between the resin and the knitted structure; interfacial strength was not measured. Before weathering, the 20-layer two-sided (20L-2S) architecture exhibited the highest maximum engineering stress, reaching 13.11 ± 0.37 MPa in the wale direction and 7.44 ± 0.28 MPa in the course direction. In contrast, the 20-layer one-sided (20L-1S) architecture retained substantially greater extensibility, reaching maximum engineering strains of 183.94 ± 2.45% and 217.34 ± 2.88% in the wale and course directions, respectively. Thus, two-sided printing maximized load-bearing capacity, whereas one-sided 20-layer printing provided a better balance between reinforcement and preservation of the large-strain response of the knitted substrate. Accelerated weathering reduced the maximum engineering stress of fabric-supported laminates by 5.4-18.7% and maximum engineering strain by 2.1-21.1%, depending on architecture and loading direction. Unsupported APR laminates exhibited 59.9-77.2% increases in maximum engineering stress after exposure, without a corresponding increase in strain capacity. The contrasting response is consistent with APR post-curing or stiffening combined with reduced Nylon 66 extensibility, although chemical and interface-specific tests are required to distinguish these mechanisms. The results demonstrate that continuous 3DPP can produce mechanically integrated textile-photopolymer laminates with tunable strength-extensibility relationships relevant to flexible technical textile structures.