Study on some alkoxysilanes used for hydrophobation and protection of wood against decay

Published Date

June 2009, Vol.63(4):456–461, doi:10.1016/j.ibiod.2008.12.003

Title 

Study on some alkoxysilanes used for hydrophobation and protection of wood against decay

• Author 

• Dmitri Panov ^a,,
• Nasko Terziev ^b

• aTartu University, Faculty of Science and Technology, Institute of Chemistry, Jakobi 2, Tartu 51014, Estonia
• bSwedish University of Agricultural Sciences, Department of Forest Products/Wood Science, 750 07 Uppsala, Sweden

Received 27 May 2008. Revised 3 December 2008. Accepted 23 December 2008. Available online 1 February 2009.

Abstract

Two types of silanes, namely aklylalkoxysilanes and arylalkoxysilanes, were used for wood impregnation aiming at hydrophobisation of the ligno-cellulose material. The suggested mixture of alkyltriethoxysilanes and dialkyldiethoxysilanes improved water repellence when compared to conventionally used silanes. An attempt to immobilise boric acid with the siloxane matrix was also done. Decay resistance of the treated samples was tested by soil-jar test using the brown rot fungus Postia placenta.

Features of the impregnated wood such as moisture content, swelling, anti-swelling efficacy and weight percentage gain were not significantly related to the mass loss of samples caused by the fungus. Samples impregnated with EtPhSi(OEt)₂ silanes showed improved durability (3.5–11.5% mass loss). Addition of boric acid to two of the silanols showed the best result for durability of wood, i.e. the lowest mass loss of 2.3 and 1.1%. These treatments upgraded the wood to “very durable”, a significant improvement from its natural status, i.e. slightly durable. The studied alkoxysilanes have moderate ability to penetrate the wood cell wall and hence to improve its hydrophobicity. These silanes are promising although more research should be carried out on the degree of oligomer polymerisation in the wood cell wall.

Keywords

Alkoxysilane

Anti-swelling efficacy

Boric acid

Hydrophobisation

Postia placenta

Scots pine sapwood

Wood decay

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