MAE Department - PG Seminar - Valorization of Biomass and Waste Plastics for Sustainability

My research group’s focus is the valorization of low-cost feedstock such as biomass and waste plastics to fuels, chemicals, and materials for energy and environmental sustainability. In this talk, I will describe our research progress on developing low-cost carbon-based materials from biomass residues. Carbon fiber is popular in many applications, but its widespread application is hindered by its high production cost. Although lignin is a promising low-cost alternative precursor, the low tensile properties of lignin-based carbon fiber have been a bottleneck and barrier. To overcome the intrinsically defected lignin structure not having molecular linearity, we proposed a “deconstruction followed by controlled reconstruction” concept to transform lignin into a linear thermoplastic precursor. An arylate thermoplastic polymer synthesized from lignin bio-oil was melt-spun to obtain carbon fibers with a tensile strength of 1.7GPa and tensile modulus of 182GPa. More recently, we developed a thermochemistry and mechano-chemistry integrated fabrication method to manipulate the lignin structure. Based on this novel method, we achieved carbon fibers with an unprecedented tensile strength of 2.45 GPa and tensile modulus of 236 GPa using sole lignins without chemical pretreatment. Other than carbon fibers, we also developed biobased carbon nano-onion. Carbon nano-onion is a relatively new member of nanocarbons, having broader potential applications in biomedicals, energy storage, sensors, and more. However, its fossil-based precursors, harsh synthesis conditions, and extremely high costs (>$1M/ton) prevent its broader applications. We developed a robust electricity-based method to synthesize oxygen-functionalized carbon nano-onions from biochar or lignins agnostic to feedstock type. We found that 0.1-0.5wt% of biobased carbon nano-onions in PLA can significantly improve the mechanical, thermal, and gas barrier properties of the biobased polymer, far outperforming other carbon-based additives or fillers, including carbon nanotubes.