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Article

Structural and Thermal Analysis of Softwood Lignins from a Pressurized Hot Water Extraction Biorefinery Process and Modified Derivatives

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Johan Gadolin Process Chemistry Centre, Åbo Akademi University, Biskopsgatan 8, 20500 Turku/Åbo, Finland
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Department of Chemistry, Saint Petersburg State Forest Technical University, 194021 Saint Petersburg, Russia
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Division of Chemistry of Renewable Resources, Department of Chemistry, University of Natural Resources and Life Sciences, Konrad-Lorenz-Strasse 24, A-3430 Tulln, Austria
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CH-Bioforce Oy, Ahventie 4 A 21-22, FIN-02170 Espoo, Finland
*
Author to whom correspondence should be addressed.
Academic Editor: Derek J. McPhee
Molecules 2019, 24(2), 335; https://doi.org/10.3390/molecules24020335
Received: 19 December 2018 / Revised: 13 January 2019 / Accepted: 16 January 2019 / Published: 18 January 2019
(This article belongs to the Special Issue Lignin for Energy, Chemicals and Materials)
In this work we have analyzed the pine and spruce softwood lignin fraction recovered from a novel pressurized hot water extraction pilot process. The lignin structure was characterized using multiple NMR techniques and the thermal properties were analyzed using thermal gravimetric analysis. Acetylated and selectively methylated derivatives were prepared, and their structure and properties were analyzed and compared to the unmodified lignin. The lignin had relatively high molar weight and low PDI values and even less polydisperse fractions could be obtained by fractionation based on solubility in i-PrOH. Condensation, especially at the 5-position, was detected in this sulphur-free technical lignin, which had been enriched with carbon compared to the milled wood lignin (MWL) sample of the same wood chips. An increase in phenolic and carboxylic groups was also detected, which makes the lignin accessible to chemical modification. The lignin was determined to be thermally stable up to (273–302 °C) based on its Tdst 95% value. Due to the thermal stability, low polydispersity, and possibility to tailor its chemical properties by modification of its hydroxyl groups, possible application areas for the lignin could be in polymeric blends, composites or in resins. View Full-Text
Keywords: lignin characterization; pressurized hot water extraction; biorefinery; condensed structures; NMR analysis; thermal analysis; lignin modification lignin characterization; pressurized hot water extraction; biorefinery; condensed structures; NMR analysis; thermal analysis; lignin modification
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MDPI and ACS Style

Lagerquist, L.; Pranovich, A.; Sumerskii, I.; von Schoultz, S.; Vähäsalo, L.; Willför, S.; Eklund, P. Structural and Thermal Analysis of Softwood Lignins from a Pressurized Hot Water Extraction Biorefinery Process and Modified Derivatives. Molecules 2019, 24, 335. https://doi.org/10.3390/molecules24020335

AMA Style

Lagerquist L, Pranovich A, Sumerskii I, von Schoultz S, Vähäsalo L, Willför S, Eklund P. Structural and Thermal Analysis of Softwood Lignins from a Pressurized Hot Water Extraction Biorefinery Process and Modified Derivatives. Molecules. 2019; 24(2):335. https://doi.org/10.3390/molecules24020335

Chicago/Turabian Style

Lagerquist, Lucas, Andrey Pranovich, Ivan Sumerskii, Sebastian von Schoultz, Lari Vähäsalo, Stefan Willför, and Patrik Eklund. 2019. "Structural and Thermal Analysis of Softwood Lignins from a Pressurized Hot Water Extraction Biorefinery Process and Modified Derivatives" Molecules 24, no. 2: 335. https://doi.org/10.3390/molecules24020335

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