X-Ray Diffraction Analysis of Kraft Lignins and Lignin-Derived Carbon Nanofibers

Abstract

Lignin is a renewable material and it is abundantly available as low priced industrial residue. Lignin-based carbon fibers are economically attractive and sustainable. In addi tion, remarkably oxidized molecule o f the lignin decreases the required time and temper ature o f the thermostabilization process compared to other carbon fiber precursors such as polyacrylonitrile (PAN); and thus, decreases the processing cost o f carbon fiber pro duction. The fraction 4 o f softwood Kraft lignin (SKL-F4) was previously shown to be spinnable via electrospinning to produce carbon nanofibers. In this paper, we character ized different Kraft lignin powders through X-ray diffraction (XRD) analysis to measure the mean size o f the ordered domains in different fractionations o f softwood and hard wood samples. According to our results, SKL-F4 has largest ordered domains among SKLs and highest hydroxyl content according to Fourier transform infrared (FTIR) anal ysis. In addition, variations in the XRD patterns during carbon nanofiber formation were studied and the peak fo r (101) plane in graphite was observed in the carbon nanofiber carbonized at 1000°C.

Petroleum Sorbers Based on Renewable Alkyd Resin and Lignin

“…The XRD of the composites also showed the main peaks of the magnetic particles. In turn, the composite filled with lignin presented a new broad scattering center at 23.21°, which corresponds to the hardwoods fractions of lignin . The particle size calculation was performed using Scherrer's Equation.…”

Processing–Structure–Property Relationships for Lignin‐Based Carbonaceous Materials Used in Energy‐Storage Applications

“…In any case, the S and Na contents are nominally no more than 2.2 %. According to the literature, the presence of S might improve the graphitic structure of KSL by allowing stronger intermolecular cross‐linkages during the dehydrogenation process . The iron (Fe) content was observed after the ball‐milling process; therefore, we suspect that Fe is a contaminant from the stainless steel balls used in ball milling.…”

“…Initially, KSL powder has a smooth and broad pattern with few distinguishable peak reflections. There is a peak positioned at 21.09° and ordered domain size of 0.74 nm, in agreement with reported results of KSL showing a peak positioned at 19.42° with an ordered domain size of 0.67 nm . KSL is an amorphous polymer that exhibits a colloidal structure with a dispersed higher‐molecular‐weight phase contributing to the amorphous halo.…”

“…These peaks are affected by the relative distances and spaces between parallel and edge‐on aromatic rings. Sulfate‐group contamination in the KSL structure can assist in the formation of the graphitic structure . The presence of (002), (100), (101), and (110) reflections after pyrolysis at 1000 °C indicates the formation of crystalline domains in the material.…”

“…Furthermore, crystal planes of the form ( hkl ) are influenced by translational stacking faults; this behavior can be observed in the 2000 °C sample by the appearance of the (101) plane . It is important to note that graphite formation is characterized by the (101) reflection . We assume that the (112) peak is characteristic of the KSL material, as it disappears after processing.…”