A new carbon fiber from lignin

A new carbon fiber was prepared from the lignin (steam-exploded lignin), which was isolated from steam-exploded birch wood (Betula platyphylla). The lignin was modified to melt thermally on hydrogenolysis. The chloroform soluble and carbon disulfide insoluble fraction (HL) of the reaction products was heated at 300–350°C for 30 min, giving a molten viscous material (HHL). The HHL had a softening point of 110°C and melted at over 145°C to form viscous liquid. When HHL was subjected to a spinning test, according to a conventional fusion spinning method at a speed over 100 m/min, a fine filament could be continuously formed through a pinhole (diameter: 0.3 mm). After the filaments were heated in air at 1–2°C/min up to 210°C, by which time the filament was converted to have an infusible property, the filaments were carbonized by heating from a room temperature to 1000°C at a heating rate of 5°C/min in a stream of nitrogen. The typical properties of the lignin based carbon fiber were as follows: Fiber diameter = 7.6 ± 2.7μ Elongation = 1.63 ± 0.29% Tensile strength = 660 ± 230 MPa; Modulus of elasticity = 40.7 ± 6.3 GPa. The chemical structure of the precursor was remarkably changed from that of the original lignin, indicating the elimination of aliphatic functional groups implied originally in the starting material.     

Thermal treatment of pyrolytic lignin and polyethylene terephthalate toward carbon fiber production

In this work, pyrolytic lignin (PL) was thermally co-treated with polyethylene terephthalate (PET) to produce carbon fiber precursor. The produced PL-PET precursors were thoroughly characterized and analyzed, and then being processed into carbon fiber. It was found that a novel precursor, rather than their physical blending, was formed by the thermal co-treatment, indicating there were strong interactions between PL and PET. The novel PL-PET precursors had enhanced thermal properties and rheological characteristics, therefore are more suitable for processing into better carbon fibers based on melt-spinning method. In this study, the precursor fibers derived from the co-treatment of PL and 5% PET were also stretched under tension during stabilization step to reduce the fiber diameter and improve molecular orientation. The resulting carbon fibers with an average diameter of 12.6 μm had the tensile strength of up to 1220 MPa. This work demonstrated that PET could be used to improve the processability and quality of lignin-based carbon fiber when it is chemically bonded with lignin-based precursor. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48843.     

Recent advances in low‐cost carbon fiber manufacture from lignin

The confluence of two US energy policy mandates, the 2012 Corporate Average Fuel Economy Standards and Renewable Fuels Standard #2, provide the opportunity to examine the possibility of high‐value materials from lignin with increased depth. In this case, the desire to provide lighter, low‐cost materials for automobiles to reduce fuel consumption, and to improve the economics of biorefineries for fuel production, have led to an increased interest in low‐cost carbon fiber manufacture from lignin. For this review the authors provide the context of subject matter importance, a cost comparison of potential low‐cost carbon fibers, a brief review of historical work, a review of more recent work, and a limited technical discussion followed by recommendations for future directions. As the available material for review is limited, the author includes many references to publicly available government documents and reviewed proceedings that are generally difficult to locate. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 713‐728, 2013     

Potential of producing carbon fiber from biorefinery corn stover lignin with high ash content

The possibility of producing carbon fiber from an industrial corn stover lignin was investigated in the present study. As‐received, high‐ash containing lignin was subjected to methanol fractionation, acetylation, and thermal treatment prior to melt spinning and the changes in physiochemical and thermal properties were evaluated. Methanol fractionation removed most of the impurities in the raw lignin and also selectively removed the molecules with high melting points. However, neither methanol fractionation nor thermal treatment rendered melt‐spinnable precursors. The precursors were highly viscous and decomposed easily at low temperatures, attributed to the presence of H, G phenolic units, and abundant hydroxycinnamate groups in herbaceous lignin. A two‐step acetylation of methanol fractionated lignin greatly improved the mobility of lignin, while enhancing the thermal stability of the precursor during melt‐spinning. Fourier Transform Infrared and 2D‐NMR analysis showed that the contents of phenolic and aliphatic hydroxyls, as well as the hydroxycinnamates, decreased in the acetylated precursors. The optimum precursor was a partially acetylated lignin with a glass transition temperature of 85 °C. Upon oxidative stabilization and carbonization, the carbon fibers with an average tensile strength of 454 MPa and modulus of 62 GPa were obtained. The Raman spectroscopy showed the I_D/I_G ratio of the carbon fiber was 2.53. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45736.     

A new modification method of exploded lignin for the preparation of a carbon fiber precursor

A lignin-pitch for carbon fiber was prepared in a high yield from exploded lignin on phenolysis followed by heat treatment under a vacuum. The lignin-pitch had an excellent spinnability in the melt state to form a fine filament. The green fibers were easily made infusible when heated in air at a relatively high heating rate (15-60°C/h). The lignin-based carbon fiber was produced in 43.7% of yield based on a starting material. The tensile strength was more than 400 MPa, indicating that the lignin-based carbon fiber is classified into a general purpose grade. © 1993 John Wiley & Sons, Inc.     

In-cell solid-state NMR as a tool to study proteins in large complexes

A major limitation of solution NMR is molecular tumbling, which is often too slow for detection. Here we demonstrate that solid-state NMR spectroscopy in combination with flash freezing of cells can be used to detect proteins in the cellular environment and provides information on backbone chemical shifts.     

Vanillin production from lignin oxidation in a batch reactor

Vanillin production from lignin oxidation is a biomass-based process that employs a by-product of the pulp and paper industry and air to obtain a high-added value compound. However, lignin is an organic polymer with a structure that depends strongly on the source and the conditions to obtain vanillin should be adjusted for different samples.     

木质素纳米颗粒/天然纤维基活性碳纤维材料的制备及其电化学性能

以木质素纳米颗粒（LNPs）负载的天然纤维复合材料为研究对象,利用KOH活化的方法对其进行处理制备生物质基复合多孔活性碳纤维电极材料。随后在三电极体系中对合成的复合多孔活性碳纤维电极材料进行了电化学性能测试。研究表明,在0.5A/g的电流密度下,KOH活化的复合碳纤维电极材料的比电容为351.13F/g,远高于相同条件下未活化的复合碳纤维电极材料的比电容（7.88F/g）和未负载LNPs的天然纤维基活性碳纤维材料（306.50F/g）。而且在活化过程中,负载在纤维表面的LNPs会形成多孔的活性碳层结构,这会进一步提高复合活性碳纤维材料的循环稳定性,同时LNPs中丰富的羟基赋予复合材料额外的赝电容。在10A/g的电流密度下经过10000次循环后,复合活性碳纤维电极材料的电容保持率仍然为95%,高于未负载LNPs的活性碳纤维电极材料的电容保持率87%。结果表明,木质素纳米颗粒/天然纤维基活性碳纤维材料是一种理想的电极材料,本研究也为LNPs在生物质碳纤维作为储能电极材料的高值化应用提供了一条新途径。     

Adsorption properties of active carbon from lignin

Regularities of changing the adsorption characteristics of lignin-based active carbon (AC) with the temperature and time of activation with steam are studied. The extreme changes in the plots of the specific surface and adsorption activity with respect to methylene blue (MB) and iodine with maxima at 800°C are observed with an increase in the activation temperature from 400 to 900°C. The dependence of the AC yield on the activation time at 800°C indicates the presence of two regions of interaction of lignin with steam. The gasification rate in region I (τ_a up to 30 min) is by 33 times higher than that in region II (τ_a = 30–120 min), which is determined by different reactivities of structural fragments of two types. The gasification of the highly reactive structural fragments of the type I results in the formation of a porous system of AC, and their complete burning-out corresponds to limiting values of the specific surface and adsorption activity with respect to iodine. Subsequent activation is determined by the gasification of the structural fragments of the type II and leads to the formation of AC characterized by the maximum adsorption activity with respect to MB.     

The production of submicron diameter carbon fibers by the electrospinning of lignin

Lignin fibers with and without platinum were synthesized in a single step by electrospinning of lignin/ethanol/platinum acetyl acetonate and lignin/ethanol solutions, respectively. The fibers obtained were stabilized in air at low temperature to avoid fiber fusion during the subsequent carbonization process. The effect of the carbonization temperature (600-1000 °C) on surface chemistry, morphology, textural properties, and oxidation resistance of the final carbon fibers was studied. The carbonization process decreased the oxygen content of the fibers, increasing the carbon and surface platinum proportion and producing a well developed microporous structure. Carbon fibers with and without platinum with apparent surface areas of 1178 and 1195 m²/g, respectively, and micropore volumes of around 0.52 cm³/g were obtained. The diameter of the carbon fibers obtained is in the range of 400 nm to 1 μm. Carbon fibers with surface platinum of 0.6% in weight were obtained. The carbon fibers with and without platinum showed high oxidation resistance despite their highly developed porous structure.     

桉木木素的付立叶变换红外光谱研究

付立叶变换红外光谱是分析木素结构的一种有效手段。本研究用付立叶变换红外光谱法分析了桉木分离木素和桉木原本木素，并对两者进行了比较。结果表明桉木磨木木素由愈创木基和紫丁香基组成，其中紫丁香基占40％～45％，愈创木基占55％～60％，甲氧基含量为每C9单元1．40个左右。与杉木和山毛榉相比，桉木磨木木素中含有较多的乙酸基和共轭羰基，并且含有一定量的芳香酸的酯类。用差示光谱法对桉木原本木素进行了研究，结果表明原本木素比磨木木素含有更多的氢键联接和乙酸基，但原本木素中的α-羰基含量较少，紫丁香基结构单元的比例也较小，结果还表明磨木木素可能更多地来源于木材纤维细胞次生壁。     

大丝束碳纤维应用研究

大丝束碳纤维及其复合材料应用研究概况。     

Bio-renewable precursor fibers from lignin/polylactide blends for conversion to carbon fibers

Lignin, a highly aromatic biopolymer extracted as a coproduct of wood pulping, was investigated as a suitable precursor for carbon fibers. Lignin was chemically modified and blended with poly(lactic acid) (PLA) biopolymer before melt spinning into lignin fibers. The chemical modification of raw lignin involved butyration to form ester functional groups in place of polar hydroxyl (–OH) groups, which enhanced the miscibility of lignin with PLA. Fine fibers were extracted and spooled continuously from lignin/PLA blends with an overall lignin concentration of 75 wt.%. The influence of chemical modification and physical blending of lignin with PLA on the resulting fiber was studied by analyzing the microstructure of the fibers using transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The influence of blend composition on the phase behavior was studied by differential scanning calorimetry (DSC). The effect of composition on the mechanical properties was studied by tensile tests of the lignin/PLA blend fibers. The thermal stability and carbon yield of the blended fibers with different concentrations of lignin were characterized by thermogravimetric analysis (TGA). The microstructure analysis of carbon fibers produced from lignin/PLA blends revealed composition dependent microporous structures inside the fine fibers.     

碳纤维生产废气焚烧法处理工艺探讨

采用焚烧炉直接焚烧法处理碳纤维生产中的炭化废气,探讨了柴油流量、柴油压力、炉膛压力等工艺条件对焚烧炉运行状况及处理效果的影响。结果表明:在柴油流量大于12.5 L/h、柴油压力大于0.4MPa、炉膛压力-1 200~-600 Pa条件下,焚烧炉可以连续稳定运行;炭化废气经焚烧炉连续稳定处理后,碳纤维生产废气中氰化氢去除率达98%以上,达到《GB16297—1996大气污染物综合排放标准》要求。     

Efficiently activated carbon fiber derived from grafted novoloid fiber

Graft copolymerization of methyl methacrylate onto novoloid fiber was carried out by the electron beam mutual irradiation method. The characteristics of the grafted fiber were almost the same as those of the original novoloid fiber. The grafted fiber was carbonized and activated to yield an efficiently activated carbon fiber. The yield and the specific surface area of the activated carbon fiber, derived from the grafted novoloid fiber, were much greater than those derived from the original novoloid fiber. This is because grafted poly(methyl methacrylate) decomposes into monomer and gaseous products, forming pores on the surface and inside of the novoloid fiber on heating. © 1993 John Wiley & Sons, Inc.     

Circulating flow reactor for recycling of carbon fiber from carbon fiber reinforced epoxy composite

For the purpose of development of a chemical recycling process for carbon fiber from carbon fiber reinforced epoxy composite, a new chemical recycling system using nitric acid aqueous solution has been proposed. The recycling system is composed of hexahedral circulating flow reactor made of quartz, Teflon supporter, acid resistance pump and auxiliaries. Epoxy matrix in the composite was effectively decomposed by nitric acid aqueous solution in the circulating flow reactor and carbon fiber could be recycled without any tangle or disturbance. Optimum conditions for the recycling process have been experimentally established. Tensile strength loss of recycled carbon fiber and composition of liquid phase decomposition products were analyzed.