Investigating the Shear and Thermal Behavior of Additively Manufactured Wood-PLA Biocomposites Including a Life Cycle Assessment

This study investigates the shear and thermal behavior, along with a cradle-to-gate life cycle assessment (LCA), of additively manufactured biocomposites made from underutilized aspen wood fibers and polylactic acid (PLA). Biocomposites were fabricated using a fused filament fabrication process with fiber loadings of 10, 20, and 30 wt%. The incorporation of 10 wt% untreated fibers yielded optimal mechanical performance, increasing shear strength and shear modulus by 18% and 44%, respectively, while maintaining nearly constant thermal conductivity. Higher fiber contents led to degraded properties due to increased void formation and weaker fiber–matrix interaction. To improve interfacial compatibility, fibers were chemically treated using NaOH, 3-aminopropyltriethoxysilane, and maleic anhydride. Among these, silane treatment was most effective, resulting in a 4% increase in shear strength, a 44% increase in shear modulus, and a 20% improvement in thermal conductivity at 10 wt% fiber content. LCA results showed that increasing untreated fiber content from 10 to 30 wt% reduced global warming potential (GWP) from 16.82 to 16.22 g CO₂-eq g⁻¹. Although silane-treated composites exhibited higher GWP (19.21 g CO₂-eq g⁻¹), sensitivity analysis indicated that cleaner electricity sources could reduce their GWP by approximately 79%, balancing sustainability and performance.