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Fast Curing Bio-Based Phenolic Resins via Lignin Demethylated under Mild Reaction Condition
Demethylation technique has been used to enhance lignin reactivity for preparation of phenolic resins. However, the demethylation efficiency and the demethylated lignin (DL) reactivity were still unsatisfactory. To improve the demethylation efficiency, alkali lignin was demethylated under different...
Autores principales: | , , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
MDPI
2017
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6418542/ https://www.ncbi.nlm.nih.gov/pubmed/30965731 http://dx.doi.org/10.3390/polym9090428 |
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author | Li, Jiongjiong Zhang, Jizhi Zhang, Shifeng Gao, Qiang Li, Jianzhang Zhang, Wei |
author_facet | Li, Jiongjiong Zhang, Jizhi Zhang, Shifeng Gao, Qiang Li, Jianzhang Zhang, Wei |
author_sort | Li, Jiongjiong |
collection | PubMed |
description | Demethylation technique has been used to enhance lignin reactivity for preparation of phenolic resins. However, the demethylation efficiency and the demethylated lignin (DL) reactivity were still unsatisfactory. To improve the demethylation efficiency, alkali lignin was demethylated under different mild conditions using sodium sulfite as a catalyst. Lignin and DL were characterized by (1)H-NMR (nuclear magnetic resonance) and Fourier transform infrared (FT-IR) spectroscopy to determine the demethylation mechanism. With the demethylation of lignin, the methoxyl group content decreased from 1.93 m mol/g to 1.09 m mol/g, and the phenolic hydroxyl group content increased from 0.56 m mol/g to 0.82 m mol/g. These results revealed that methoxyl groups were attacked by SO(3)(2−), and some methoxyl groups were converted to phenolic hydroxyl groups by a nucleophilic substitution reaction, generating DL with high reactivity. The chemical properties of lignin-based phenolic resins were studied by (13)C-NMR and FT-IR spectroscopy, and their physical properties were also investigated. The results indicated that lignin-based phenolic resins exhibited faster curing rate and shorter gel time. In addition, the bonding strength increased from 0.92 MPa to 1.07 MPa, and the formaldehyde emission decreased from 0.58 mg/L to 0.22 mg/L after lignin demethylated at the optimum condition. |
format | Online Article Text |
id | pubmed-6418542 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2017 |
publisher | MDPI |
record_format | MEDLINE/PubMed |
spelling | pubmed-64185422019-04-02 Fast Curing Bio-Based Phenolic Resins via Lignin Demethylated under Mild Reaction Condition Li, Jiongjiong Zhang, Jizhi Zhang, Shifeng Gao, Qiang Li, Jianzhang Zhang, Wei Polymers (Basel) Article Demethylation technique has been used to enhance lignin reactivity for preparation of phenolic resins. However, the demethylation efficiency and the demethylated lignin (DL) reactivity were still unsatisfactory. To improve the demethylation efficiency, alkali lignin was demethylated under different mild conditions using sodium sulfite as a catalyst. Lignin and DL were characterized by (1)H-NMR (nuclear magnetic resonance) and Fourier transform infrared (FT-IR) spectroscopy to determine the demethylation mechanism. With the demethylation of lignin, the methoxyl group content decreased from 1.93 m mol/g to 1.09 m mol/g, and the phenolic hydroxyl group content increased from 0.56 m mol/g to 0.82 m mol/g. These results revealed that methoxyl groups were attacked by SO(3)(2−), and some methoxyl groups were converted to phenolic hydroxyl groups by a nucleophilic substitution reaction, generating DL with high reactivity. The chemical properties of lignin-based phenolic resins were studied by (13)C-NMR and FT-IR spectroscopy, and their physical properties were also investigated. The results indicated that lignin-based phenolic resins exhibited faster curing rate and shorter gel time. In addition, the bonding strength increased from 0.92 MPa to 1.07 MPa, and the formaldehyde emission decreased from 0.58 mg/L to 0.22 mg/L after lignin demethylated at the optimum condition. MDPI 2017-09-07 /pmc/articles/PMC6418542/ /pubmed/30965731 http://dx.doi.org/10.3390/polym9090428 Text en © 2017 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/). |
spellingShingle | Article Li, Jiongjiong Zhang, Jizhi Zhang, Shifeng Gao, Qiang Li, Jianzhang Zhang, Wei Fast Curing Bio-Based Phenolic Resins via Lignin Demethylated under Mild Reaction Condition |
title | Fast Curing Bio-Based Phenolic Resins via Lignin Demethylated under Mild Reaction Condition |
title_full | Fast Curing Bio-Based Phenolic Resins via Lignin Demethylated under Mild Reaction Condition |
title_fullStr | Fast Curing Bio-Based Phenolic Resins via Lignin Demethylated under Mild Reaction Condition |
title_full_unstemmed | Fast Curing Bio-Based Phenolic Resins via Lignin Demethylated under Mild Reaction Condition |
title_short | Fast Curing Bio-Based Phenolic Resins via Lignin Demethylated under Mild Reaction Condition |
title_sort | fast curing bio-based phenolic resins via lignin demethylated under mild reaction condition |
topic | Article |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6418542/ https://www.ncbi.nlm.nih.gov/pubmed/30965731 http://dx.doi.org/10.3390/polym9090428 |
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