(413g) Toward Feedstock Design for Biomaterial: Novel Biomass Structure Characteristics Determining Properties of Lignin-Based Carbon Fiber

Lignin has been explored extensively as a renewable feedstock for biomaterials, considering its abundance as a major component of plant cell wall and its sustainability as a waste of lignocellulosic biorefinery and paper-making industries. Despite the extensive efforts on defining process-property relationship, it remains largely unknown how lignin biosynthesis and precursor chemistry in planta would impact on the properties of biomaterials. Current knowledge about reducing lignin content to improve saccharification efficiency does not necessarily inform the feedstock for enhanced properties of biomaterials. Such inadequate understanding fundamentally limited the feedstock design and selection to improve carbon material properties toward broader commercial application. Using lignin from a broad range of biomass feedstock for carbon fiber manufacturing, we have fundamentally explored the structure-function relationship between lignin chemistry and carbon fiber properties, for both mechanical and electro-conductive performance. Specifically, lignin extracted from hardwood (sugar maple), softwood (loblolly pine and red cedar), and herbaceous plant (corn stover and switchgrass) were used for carbon fiber manufacturing, considering the very different lignin and biomass structures from these feedstock. Linear regression models were established to define the relationship between carbon fiber mechanical properties (Elastic Modulus, Tensile Strength, and Elongation) with lignin structure characteristics (content, composition, linkage profile and others), along with carbon fiber microstructures (crystallite content and size). The results highlighted that traditional biomass characteristics such as lignin content and composition don’t impact the properties of lignin-based carbon fiber. Instead, the content of β-O-4 linkage correlates significantly with tensile strength and elastic modulus of lignin carbon fiber, indicating that the more linear β-O-4 linkage would promote carbon fiber performance. Besides the mechanical property, electro-conductive property is essential for broader energy application of lignin-based carbon fiber, yet the mechanisms controlling the electrocoductive properties of lignin-based carbon fiber is largely unknown. We hereby demonstrated that a higher β-O-4 content also promotes electroconductive performance of carbon fiber. Moreover, we also found that higher β-O-4 linkage profile defines the crystallite content and size of the resultant carbon fiber, which could be due to the better miscibility with the guest polymer. Overall, the study established lignin linkage profile, in particular, β-O-4 content as the new structure determinants for biomaterial property, which could guide the future biomass feedstock development.