Sustainable Sawdust/Epoxy‐Nanosilica Sandwich Composites With Textured Aluminum Face Sheets

ABSTRACT This study outlines a method to create sustainable sandwich composites through core and interface design. The core was epoxy resin with 45 wt.% sawdust, combined with silicon dioxide (SiO ₂ ) at 0–8 wt.%, prepared via a cast‐in‐place method to achieve uniform filler mixing and enhance the filler‐matrix interactions. The face sheets were aluminum composites that were mechanically modified with coarse, medium, and fine cross‐hatching to introduce porosity, enabling mechanical interlocking with the core of the sandwich. The mechanical and tribological performance was assessed using flexural (ASTM C393), compressive (ASTM C365), and wear resistance tests. The results showed that the SiO ₂ 6 wt.% core had the best properties, with flexural strength of 96 MPa, flexural modulus of 8.8 GPa, compressive strength of 115 MPa, and wear rate of 3.8 × 10 ⁻⁸ mm ³ /N·m. Of the different surface modifications, the medium texture aluminum face sheets with the 6 wt.% SiO ₂ core showed the best overall sandwich composite performance, with a flexural strength of 387 MPa, facing stress of 473.6 MPa, core shear stress of 13.4 MPa, and toughness of 16.4 kJ/m ³ . The improved properties are linked to improved bonding at the core and face sheets, made possible by the combination of the filler and mechanical interlocking. This approach is an environmentally sustainable means of creating lightweight structural composites, and applications may include lightweight panels, automotive interior, and engineered boards. This work supports the hypothesis that waste‐derived fillers and surface engineering can help support sustainable composites.