Impact of Thermal Oxidative Stabilization on the Performance of Lignin-Based Carbon Nanofiber Mats

Abstract

Lignin is a renewable biopolymer considered as a potential precursor for low-cost carbon materials. Thermal oxidative stabilization (TOS) is an important processing step to maintain fiber geometry during carbonization, yet the impact of TOS on the properties of lignin-based carbon materials has not been clearly identified in the literature. Yield, change in fiber diameter/distribution, elemental composition, and mechanical properties were explored for both stabilized and carbonized lignin fibers. Vibrational spectroscopy and solid-state 13 C nuclear magnetic resonance spectroscopy were used to analyze the changes in lignin molecular structure after exposure to various heating conditions during the TOS steps. Further, studies were focused on the effects of TOS conditions on the resulting carbon structure of fiber mats through Raman spectroscopy measurements and electrical conductivity analysis. Although TOS conditions influenced the properties of the oxidized lignin fiber mats, properties of the carbonized samples were invariant to the TOS procedures used in this study over most of the conditions. As a result, there was flexibility for the parameters (time and temperature) in the TOS process when conditioning softwood lignin materials for carbon fibers.

Improved Procedure for Electro-Spinning and Carbonisation of Neat Solvent-Fractionated Softwood Kraft Lignin

“…As seen in Table 2, the electrical conductivity of the lignin bres increased with carbonisation temperature from 1000°C to 1200°C and 1500°C. The lignin bres that were carbonised at 1500°C show electrical conductivity comparable to those reported in literature for softwood Kraft lignin (230 S m − 1 ) 2,52 .…”

“…The ratio of intensities of D to G are represented by I D /I G whilst A D /A G shows the ratio of areas. 51,52 Results…”

3D Thermal Network Supported by CF Felt for Improving the Thermal Performance of CF/C/Epoxy Composites

“…However, when the content of the thermal conductive filler is too high, the granular material is prone to agglomeration, which makes the composite have certain defects and destroys the mechanical property. As a one-dimensional (1D) material, CF has high thermal conductivity in the axial direction of the fiber [ 36 , 37 ]. The CF filaments easily overlap each other inside the matrix to form a denser heat-conducting network [ 38 , 39 ].…”

Hardwood versus softwood Kraft lignin – precursor-product relationships in the manufacture of porous carbon nanofibers for supercapacitors

“…13,24 Recently, Cho et al showed that the stabilization temperature and heating rate have only a minor effect on the structure of carbonized electrospun nanober mats from sowood lignin. 25 These differences did not correlate with changes in mechanical performance. 25 Various sowood and hardwood lignin-derived carbon nanobers (LCNFs) were tested in supercapacitors operating in different electrolytes and cell congurations.…”

“…25 These differences did not correlate with changes in mechanical performance. 25 Various sowood and hardwood lignin-derived carbon nanobers (LCNFs) were tested in supercapacitors operating in different electrolytes and cell congurations. [26][27][28][29][30] To date, a clear inference concerning the reasons for superior performance of one lignin compared with another is out of reach.…”