Lignin-based Carbon Nano Onion as Interfacial Modifier To Obtain High-performance Polylactic Acid-Wood Flour Nanocomposites

Herein, we report high-performance, 100% biobased nanocomposites prepared using a chemical and solvent-free approach. Lignin was used to synthesize oxygen-functionalized carbon nano-onion (CNO) using a Joule heating method. CNO was then co-extruded with polylactic acid (PLA) and wood flour to prepare nanocomposites without the pretreatment of wood or coupling agents. It showed that the addition of CNO can simultaneously improve the tensile strength, tensile modulus, impact strength, and ductility of the composites. Additionally, the CNO-containing composite had enhanced thermal stability, flame retardancy, and reduced water absorption. Our investigation indicates that the superior reinforcement effect observed in the CNO-reinforced composites is attributed to the role of CNO as a coupling agent and interfacial modifier. Turbostratic graphene structure of CNO with amphiphilic surface properties provides both structural integrity and excellent chemical competitiveness. At the same time, the quasi-sphere geometry of nanoparticles offers a high interfacial area and a dimensionless interface.