Structural and thermal analysis of softwood lignins from a pressurized hot water extraction biorefinery process and modified derivatives

A1 Journal article (refereed)


Internal Authors/Editors


Publication Details

List of Authors: Lucas Lagerquist, Andrey Pranovich, Ivan Sumerskii, Sebastian von Schoultz, Lari Vähäsalo, Stefan Willför, Patrik Eklund
Publisher: MDPI
Publication year: 2019
Journal: Molecules
Journal acronym: Molecules
Volume number: 24
Issue number: 2
Number of pages: 15
ISSN: 1420-3049
eISSN: 1420-3049


Abstract

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 degrees C) based on its T-dst 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.


Keywords

Biorefinery, Condensed structures, lignin characterization, lignin modification, NMR analysis, thermal analysis

Last updated on 2020-05-06 at 06:17