LIGNIN AS A MODIFIER FOR ENHANCING THE DURABILITY OF WOOD

Jelena CHIRKOVA
Dr. Chem., Researcher - Latvian State Institute of Wood Chemistry
Address: 27 Dzerbenes Str., LV-1006 Riga, Latvia
E-mail: cirkel@edi.lv

Ingeborga ANDERSONE
Dr. Chem., Senior Researcher - Latvian State Institure of Wood Chemistry
Address: 27 Dzerbenes Str., LV-1006 Riga, Latvia
E-mail: brunoan@edi.lv

Bruno ANDERSONS
Dr. Chem., Researcher - Latvian State Institute of Wood Chemistry
Address: 27 Dzerbenes Str., LV-1006 Riga, Latvia
E-mail: brunoandersons@edi.lv

Nina KURNOSOVA
Dr. Chem., Researcher - Latvian State Institute of Wood Chemistry
Address: 27 Dzerbenes Str., LV-1006 Riga, Latvia
E-mail: kurnosova@edi.lv

Abstract: To replace traditional wood preservatives, containing heavy metals, different methods for modification of wood (thermal and chemical, use of organic preservatives etc.) are proposed for enhancing the biological resistance of wood. Great energy consumption, high cost of modifiers and their unfavourable impact on the environment are assigned to drawbacks of these methods. In the present work, to enhance the durability of wood, it is proposed to introduce into wood channels (canals, lumens and intercellular spaces) lignin - a substance that is both wood- and environment-friendly. Pine wood samples were impregnated with alkali lignin aqueous solutions under vacuum. Despite the high hydrophility of modified wood, its exposure on cultures of brown and white rots during 6 weeks has shown the high efficiency of lignin for enhancing the durability of wood with regard to both rots. Sorption of water study and density measure demonstrate that, upon modification, the interstructural bonds become weaker, the volume of narrow (micro- and meso-) pores increases almost twice, and the volume of broad pores (macropores) of wood decreases by third. It is concluded that lignin fills partially (by 13%) the channels, blocking the entries to them and hampering the diffusion of fungal enzymes to the cell wall surface.

Key words: wood, biodegradation, lignin, water sorption, density, modification.

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