Investigation of the chemical modifications of beech wood lignin during heat treatment |
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Authors: | Nicolas Brosse Roland El Hage Mounir Chaouch Mathieu Pétrissans Stéphane Dumarçay Philippe Gérardin |
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Institution: | Laboratoire d’Etudes et de Recherche sur le Matériau Bois, EA 4370, Nancy Université, BP 70239, 54506 Vandoeuvre les Nancy Cédex, France |
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Abstract: | Holocellulose, Klason lignin and milled wood lignin (MWL) of beech wood were extracted before and after heat treatment and analysed using CP MAS 13C NMR, 13C NMR, 31P NMR and size exclusion chromatography (SEC). Experimental results showed that the thermal treatment degrades hemicelluloses and affects lignin polymer through depolymerisation due mainly to cleavage of β-aryl-ether linkages and recondensation reactions. The spectroscopic analysis of MWL demonstrated that these recondensation reactions involved mainly guaiacyl units through formation of 5,5′-biphenolic and diarylmethane structures.Analysis of molecular weight distribution of MWL by SEC indicated that average molecular weights of heat treated milled wood lignin were lower than those of native milled wood lignin. |
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Keywords: | CP/MAS 13C NMR 13C NMR 31P NMR Heat treatment Milled wood lignin Thermal degradation |
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