High wood content / Poly(Butylene succinate) composites 3D-printed by fused granulate fabrication

The development of high bio-content materials for additive manufacturing is limited by restricted filler loadings and poor melt processability in filament-based extrusion. This work demonstrates fused granulate fabrication (FGF) of poly(butylene succinate) (PBS) composites incorporating up to 55 wt% industrial birch wood dust without chemical compatibilizers. The influence of filler content on rheology, print quality, thermal behavior, and mechanical performance was systematically evaluated. Increasing wood content resulted in progressively higher melt viscosity and a transition from Newtonian to pronounced shear-thinning flow above 20 wt%, enabling improved dimensional stability during deposition. Optimal surface consolidation and interlayer fusion were achieved at 30–45 wt% filler, defining an effective processing window for highly filled PBS–wood composites. The Young’s modulus increased from 0.34 GPa for neat PBS to approximately 1.3 GPa at 25 wt% wood, and then remained at a similar level for higher filler loadings up to 55 wt%. Tensile strength exhibited a non-linear dependence on filler loading, reaching a maximum of 28.9 MPa at 35 wt% wood. Differential scanning calorimetry revealed enhanced crystallinity up to 25 wt% wood, followed by a decline at higher concentrations. Thermogravimetric analysis confirmed that all compositions remained thermally stable within the 200–220 °C processing window used for FGF. The established structure–property and processing relationships confirm that PBS–wood composites can be processed at exceptionally high loadings without compromising printability, representing a significant advance toward high bio-content materials for additive manufacturing. • Fused granulate fabrication enables printing of PBS composites with up to 55 wt% wood • Higher wood content increases viscosity and improves dimensional stability in printing • Best print quality and consolidation achieved at 30–45 wt% wood filler loading • Young’s modulus rises to ∼1.3 GPa and tensile strength up to 29 MPa