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Licensed Unlicensed Requires Authentication Published by De Gruyter May 23, 2015

Scanning UV microspectrophotometry as a tool to study the changes of lignin in hydrothermally modified wood

  • Bruno Andersons EMAIL logo , Guna Noldt , Gerald Koch , Ingeborga Andersone , Anete Meija-Feldmane , Vladimirs Biziks , Ilze Irbe and Juris Grinins
From the journal Holzforschung


Thermal modification (TM) of wood has occupied a relatively narrow but stable niche as an alternative for chemical wood protection. There are different technological solutions for TM and not all details of their effects on wood tissue have been understood. The one-stage hydrothermal modification (HTM) at elevated vapour pressure essentially changes the wood’s composition and structure. In the present paper, the changes in three hardwood lignins (alder, aspen, and birch) were observed within the cell wall by means of cellular UV microspectrophotometry. The lignin absorbances in the compound middle lamella (CML) of unmodified wood are 1.7- to 2.0-fold higher than those in the fibre S2 layer. The woods were modified in the temperature range from 140 to 180°C, while in the lower temperature range (140°C/1 h), the UV absorbances are little affected. Essential changes occur in the range of 160–180°C and the UV data reflect these by absorbtion changes, while the absorbances at 278 nm rise with factors around 2 more in the S2 layer than in the CML. The absorbance increments are interpreted as polycondensation reactions with furfural and other degradation products of hemicelluloses with the lignin moiety of the cell wall.

Corresponding author: Bruno Andersons, Latvian State Institute of Wood Chemistry, 27 Dzerbenes Str., LV-1006 Riga, Latvia, Phone: +371-67552554, +371-29472010, e-mail:


The authors gratefully acknowledge the financial support by the Latvian State Research Programme NatProd.


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Received: 2015-1-29
Accepted: 2015-4-21
Published Online: 2015-5-23
Published in Print: 2016-3-1

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