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Changes of Lignin Molecular Structures in a Modification of Kraft Lignin Using Acid Catalyst.

ABSTRACT: The purpose of this study is to modify lignin for better blending with general purpose synthetic polymers. The possible advantages by using this modification would be cost reduction, better physical properties, and biodegradability. In this study, butyrolactone-modified lignin (BLL) and tetrahydrofuran-modified lignin (THFL) were used for aliphatic chain modification of lignin using an acid-catalyzed esterification method in order to mimic the relation of lignin-carbohydrate-complex (LCC) and cellulose. The results of several analyses indicated that lignin was well modified. It was confirmed that the lignin was modified as expected and the reaction sites of the modification, as well as the reaction behaviors, were varied by the reagent types. The result of X-ray diffraction analysis (XRD) analysis indicated that modified lignin/polymer blends increased the crystallinity due to their good compatibility. It can be confirmed that the type of alkyl chain and the miscibility gap between the alkyl chain-matrix affected the mechanical properties enormously in the fungi-degradable environment. From this study, a new method of lignin modification is proposed, and it is found that modified lignin retains the property of the substituted aliphatic chain well. This method could be a proper lignin modification method.

SUBMITTER: Kim S

PROVIDER: S-EPMC5509268 | biostudies-other | 2016 Aug

REPOSITORIES: biostudies-other

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Modification of Kraft Lignin with Dodecyl Glycidyl Ether.

Project description:Kraft lignin (KL) is extensively produced in industry but is mainly burned as fuel. To broaden its use, KL was grafted with dodecyl glycidyl ether to alter its thermal properties. The reaction of KL with dodecyl glycidyl ether (DGE) was analyzed using nuclear magnetic resonance (NMR), Fourier infrared spectroscopy (FT-IR) and elemental analysis. Alternatively, KL was methylated to mask its phenolic hydroxy groups to investigate how phenolic hydroxy groups impact the grafting of the alkyl chain of DGE onto lignin (methylated Kraft lignin, MKL). The methylation facilitated the molecular weight enhancement and thermal stability reduction of Kraft lignin via grafting with DGE. The influence of grafting alkyl chains on the structural and thermal properties of KL and MKL was studied using thermogravimetric analysis and differential scanning calorimetry analysis. Our data suggest that, due to their high molecular weights and lower glass transition temperatures, the produced lignin derivatives may be promising feedstocks for composite production.

| S-EPMC6786095 | biostudies-literature

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Bacterial conversion of depolymerized Kraft lignin.

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Bacterial conversion of depolymerized Kraft lignin.

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| S-EPMC7480228 | biostudies-literature

Fungal Treatment Modifies Kraft Lignin for Lignin- and Cellulose-Based Carbon Fiber Precursors.

Project description:The kraft lignin's low molecular weight and too high hydroxyl content hinder its application in bio-based carbon fibers. In this study, we were able to polymerize kraft lignin and reduce the amount of hydroxyl groups by incubating it with the white-rot fungus Obba rivulosa. Enzymatic radical oxidation reactions were hypothesized to induce condensation of lignin, which increased the amount of aromatic rings connected by carbon-carbon bonds. This modification is assumed to be beneficial when aiming for graphite materials such as carbon fibers. Furthermore, the ratio of remaining aliphatic hydroxyls to phenolic hydroxyls was increased, making the structure more favorable for carbon fiber production. When the modified lignin was mixed together with cellulose, the mixture could be spun into intact precursor fibers by using dry-jet wet spinning. The modified lignin leaked less to the spin bath compared with the unmodified lignin starting material, making the recycling of spin-bath solvents easier. The stronger incorporation of modified lignin in the precursor fibers was confirmed by composition analysis, thermogravimetry, and mechanical testing. This work shows how white-rot fungal treatment can be used to modify the structure of lignin to be more favorable for the production of bio-based fiber materials.

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Laser-Induced Graphene Derived from Kraft Lignin for Flexible Supercapacitors.

Project description:Porous graphene was photothermally induced from kraft lignin via direct laser writing. This laser-induced graphene (LIG) possessed a hierarchical structure with a three-dimensional (3D) interconnected network ideal for its transfer from the kraft lignin/poly(ethylene oxide) (KL/PEO) film onto polydimethylsiloxane (PDMS). The resultant LIG/PDMS composite was shown to keep the intrinsic porous structure and electrically active sites of LIG. The supercapacitors (SCs) fabricated using the LIG/PDMS composite exhibited good electrochemical performance and excellent cyclic stability. More than 90% capacitance was retained after 10?000 cycles. Moreover, due to their high flexibility, the SCs were able to endure bending deformation without significantly sacrificing their capacitance. The proposed technology for the fabrication of flexible SCs based on lignin-derived LIG demonstrated great potential to use a low-cost, renewable material for the manufacture of portable and wearable electronics.

| S-EPMC7315590 | biostudies-literature

Catalysts on Formation of Carbon-Encapsulated Iron Nanoparticles from Kraft Lignin.

Project description:Effects of physical and chemical states of iron-based catalysts on the formation of carbon-encapsulated iron nanoparticles (CEINs) synthesized thermally from kraft lignin were investigated. Experimental results indicated that if solution-based iron nitrate (FeN) was used as an iron source for the catalyst, CEINs observed were ?-Fe and ?-Fe-based cores encapsulated by few layers graphitic-carbon (mostly 1-5 layers) and the majority of these CEINs were embedded in amorphous carbon matrix. The formation of graphitic-carbon shells is believed based on the dissolution and precipitation mechanism of amorphous carbon acting as the carbon source. If solid-based iron nanoparticles (FePs) were used as the catalyst, CEINs observed were ?-Fe, ?-Fe, and Fe?C-based cores encapsulated with tangled graphitic-carbon nanoribbons and carbon tubules and the majority of these CEINs were found along the edge of amorphous carbon matrix. The growth of tangled graphitic-carbon nanoribbons and carbon tubules is based on a chemical vapor decomposition process, i.e., the carbonaceous gases from kraft lignin decomposition served as the carbon source.

| S-EPMC5793637 | biostudies-literature

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