Valorization of Consolidated Bioprocessing Residues for Bioplastics

Abstract

This study demonstrates the effective valorization of consolidated bioprocessing (CBP) residues, derived from switchgrass and poplar biomass, into functional biocomposites through high-shear homogenization (HSH), and compounding with poly(butylene succinate) (PBS). HSH transformed the switchgrass and poplar CBP residues (CBP-R) into fine, uniformly distributed particles and microfibers. The composites of PBS with homogenized switchgrass residues (H-CBP-R-SG) or homogenized poplar residues (H-CBP-R-P) at a 70/30 weight ratio exhibited improved processability and mechanical integrity, with the Young's modulus for the PBS/H-CBP-R-SG and PBS/H-CBP-R-P nearly doubling to 0.66 ± 0.07 GPa and 0.65 ± 0.04 GPa, respectively, compared to neat PBS (0.36 ± 0.02 GPa). Thermal stability remained comparable to that of neat PBS, and melt flow rates stayed within processable ranges for injection molding. Beyond material performance, comprehensive techno-economic analysis (TEA) and life cycle assessment (LCA) confirmed that diverting CBP residues into composite production can improve the economic viability of the biorefinery without substantially increasing biorefinery global warming potential (GWP). At a 30 wt% blend ratio, incorporating residuals into PBS yielded a minimum selling price for the composite of $4.07/kg compared to the conventional bioplastic price of $5.00/kg. This approach aligns with circular bioeconomy principles by converting waste streams into value-added products. The successful 3D printing of these biocomposites further showcases their practical applicability, with lignocellulosic biomass acting as internal reinforcement to counter shrinkage issues observed in neat PBS, resulting in dimensionally stable and high-quality printed objects. This innovative strategy addresses key challenges in bioplastic development, including cost, compatibility, and performance, while simultaneously advancing waste minimization strategies for sustainable manufacturing systems.