Compression Behavior of Material-Extruded Soy Hull Fiber/PLA Biocomposites Across Fiber Content, Raster Architecture, and Filament Manufacturing Phase

Previous research on material-extruded soy hull fiber (SHF)/polylactic acid (PLA) has emphasized feedstock development, leaving the joint effects of composition, raster architecture, and filament production history on compression insufficiently characterized. This study addressed that gap through a factorial comparison of 192 coupons spanning four SHF contents (0, 10, 20, and 30 wt.%), four raster sequences, and three filament production positions, without compatibilizers or plasticizers. Build-direction tests measured apparent modulus, 0.2% offset yield stress, and stress at 10% toe-corrected crosshead strain. Literature benchmarking included printed polymers, printed and molded biocomposites, and furniture woods. Relative to neat PLA, 10SHF approximately retained apparent modulus, reduced yield stress by 11.1%, and increased stress at 10% strain by 9.9%; corresponding reductions at 30SHF were 25.0%, 59.9%, and 15.3%. Stress at 10% strain was below offset yield in every 0SHF coupon but above it in every 20SHF and 30SHF coupon. Raster rankings depended on composition and response; some production-position modulus differences exceeded raster contrasts. All twelve 10SHF cell mean yield stresses exceeded six wood benchmarks from one study; apparent modulus means exceeded the compiled printed natural fiber composite values. These findings support partial PLA replacement and further evaluation of short, stocky furniture components under axial compression.