Effects of the Face/Core Layer Ratio on the Mechanical Properties of 3D Printed Wood/Polylactic Acid (PLA) Green Biocomposite Panels with a Gyroid Core.

Gyroid structured green biocomposites with different thickness face layers (0.5, 1, 2 and 2.5 mm) were additively manufactured from wood/ polylactic acid (PLA) filaments using a 3D printer. The mechanical properties of the composite panels, bending properties, compressive strength (parallel to the surface), Brinell hardness, and face screw withdrawal resistance, were determined. The surface layer thickness significantly affects the mechanical properties of the composite materials. As the surface layer thickness was increased from 0.5 to 2.5 mm, all the mechanical properties significantly improved. In particular, the Brinell hardness and face screw withdrawal resistance of the specimens improved sharply when the skin thickness was higher than 2 mm. The bending strength, bending modulus, compressive strength (parallel to the surface), Brinell hardness, and face screw withdrawal resistance of the specimens with a skin of 0.5 mm were found to be 8.10, 847.5, 3.52, 2.12 and 445 N, respectively, while they were found to be 65.8, 11.82, 2492.2, 14.62, 26 and 1475 N for the specimens with a 2.5 mm skin. Based on the findings from the present study, gyroid structured composites with a thickness of 2 mm or higher are recommended due to their better mechanical properties as compared to the composites with skins that are thinner.