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.