Hybrid Green Bionanocomposites of Bio-based Poly(butylene succinate) Reinforced with Pyrolyzed Perennial Grass Microparticles and Graphene Nanoplatelets

Abstract

Bio-based poly(butylene succinate) (BioPBS) was combined with pyrolyzed Miscanthus microparticles (biocarbon) and graphene nanoplatelets to create a hybrid bionanocomposite. Pyrolyzed biomass, known as biocarbon, was incorporated into a BioPBS matrix to improve the thermo-mechanical properties of the bioplastic while simultaneously increasing the value of this co-product. Biocomposites loaded with 25 wt % biocarbon showed 57, 13, and 32% improvements in tensile modulus, heat deflection temperature, and thermal expansion, respectively. Further improvements were found when graphene nanoplatelets (GnPs) were added to the biocomposite, forming a hierarchical hybrid bionanocomposite. Two processing methods were used to incorporate graphene into the composites: (I) graphene, BioPBS, and biocarbon were added together and directly compounded, and (II) a masterbatch of graphene and BioPBS was processed first and then diluted to the same ratios as those used in the direct compounding method I. The two methods resulted in different internal morphologies that subsequently impacted the mechanical properties of the composites; little change was observed in the thermal properties studied. Bionanocomposites processed using the direct compounding technique showed the greatest increase in tensile strength and modulus: 17 and 120%, respectively. Bionanocomposites processed using a masterbatch technique had slightly lower strength and modulus but showed almost twice the impact strength compared with the direct compounding method. This masterbatch technique was found to have a superior balance of stiffness and toughness, likely due to the presence of superclustered graphene platelets, confirmed through a scanning electron microscope and a transmission electron microscope.