One of the biggest drawbacks of using European native wood species as a construction material is its tendency to degrade by fungal attack. This has lead to the development of different systems for wood preservation. Many of these systems suffer the disadvantage that they contain biocides, which can leach from the wood into the environment and damage organisms.
In this project ten silanes, 3-(2-Aminoethylamino)propyltrimethoxysilane, 3-[2-(2-aminoethylamino)ethylamino]propyltrimethoxysilane, 3-Aminopropyltrimethoxysilane, Diethoxydimethylsilane, Dodecyltriethoxysilane, Hexadecyltrimethoxysilane, N-Trimethoxysilylpropyl-N,N,N-trimethylammoniumchloride, Octyltriethoxysilane, Octyltrimethoxysilane and Phenyltrimethoxysilane, have been investigated for their ability to increase the hydrophobicity of wood and decrease shrinking and swelling, and thus increase its ability to withstand attack by fungi. In the initial phase of the project two solvents, ethanol and water were investigated to find out which of these that gave the best result for surface modification with silanes. The results showed that water as solvent gave a surface with higher hydrofobicity than when ethanol was used as solvent.
The samples treated with water as the solvent gave better surface modification, Therefore, only water was used for pressure impregnation.
It has been shown by FT-IR-spectroscopy that the silanes binds to hydroxyl groups in the wood structure.
The systems which have given the best indications to be suitable as wood preservatives after measuring of contact angles are octyltrethoxysilane, 3-(2-aminoethylamino)-propyltrimethoxysilane, 3-[2-(2-aminoethylamino)ethylamino]propyltrimethoxysilane and 3-aminopropyl-trimethoxysilane. The three last systems contain amine groups, which acts as a biocide and may be able to stop the fungi.
Keywords: Contact angles, FT-IR-spectroscopy, silanes, wood preservation
Authors
Aaserud J.
Department of chemical engineering, Norwegian university of science and technology, Institutt for kjemisk prosessteknologi, Trondheim
Larnøy E.
The Norwegian Forest and Landscape Institute, Ås, Norway
Glomm W. R.
Department of chemical engineering, Norwegian university of science and technology, Institutt for kjemisk prosessteknologi, Trondheim
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