Replacing petroleum by biomass can be economically feasible by generating revenue from the three primary biomass constituents.

Lignin was extracted from Alamo switchgrass (Panicum virgatum) and yellow polar (Liriodendron tulipifera) by organosolv fractionation at different pretreatment temperatures, and its chemical structure was studied by means of elemental analysis and spectroscopy. Thermal properties of lignins were investigated using thermogravimetric analysis and differential scanning calorimetry. Lignin fibers were produced via melt-spinning by a twin-screw extruder with a custom spinneret. Fibers were thermostabilized at different rates and finally carbonized. In both species, lignin obtained from higher severity organosolv fractionation had fewer impurities, higher content of phenolic hydroxyl groups, and more condensed structures as a result of extensive cleavage of aryl ether linkages. Higher organosolv severity improved the ability to spin fibers; in the case of switchgrass, only the high severity sample was spinnable. High severity also decreased thermostabilization time and increased tensile strength and modulus of carbon fibers. A decrease in the ratio of ether linkages to condensed units appears to be the main reason for faster stabilization. Switchgrass lignin had less thermal stability at low temperature that results in formation of volatiles, mainly due to the presence of ester-linked phenolic acids. These volatiles are more prevalent at low severity and prevent forming continuous fibers during spinning. As a result, pores forming on the surface of switchgrass fibers led to lower strength. Tuning the severity of fractionation is recommended as an easy method to change lignin characteristics, to find the proper severity range, and to produce lignin suitable for carbon fiber production.

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Pure eucalyptus Kraft lignin derived carbon fiber mats were produced based on a model workflow. It covers the preparation and characterization of the lignin precursor and the carbon materials and its testing in the final application (supercapacitor). Sequential solvent extraction was employed to produce a eucalyptus Kraft lignin precursor which could be electrospun into

A very simple method to enhance the low volumetric energy density of free-standing carbon nanofiber electrodes.

Lignin/lignin blends were used to improve fiber spinning, stabilization rates, and properties of lignin-based carbon fibers. Organosolv lignin from Alamo switchgrass (Panicum virgatum) and yellow poplar (Liriodendron tulipifera) were used as blends for making lignin-based carbon fibers. Different ratios of yellow poplar:switchgrass lignin blends were prepared (50:50, 75:25, and 85:15 w/w). Chemical composition and thermal properties of lignin samples were determined. Thermal properties of lignins were analyzed using thermogravimetric analysis and differential scanning calorimetry. Thermal analysis confirmed switchgrass and yellow poplar lignin form miscible blends, as a single glass transition was observed. Lignin fibers were produced via melt-spinning by twin-screw extrusion. Lignin fibers were thermostabilized at different rates and subsequently carbonized. Spinnability of switchgrass lignin markedly improved by blending with yellow poplar lignin. On the other hand, switchgrass lignin significantly improved thermostabilization performance of yellow poplar fibers, preventing fusion of fibers during fast stabilization and improving mechanical properties of fibers. These results suggest a route towards a 100% renewable carbon fiber with significant decrease in production time and improved mechanical performance.

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