Many wood products used as building or construction materials involve a combination of the wood material with polymers, such as adhesives, coatings, preservatives and binders in composites. Combinations of wood and polymers in outdoor exposure, however, in general have poor long-term durability. A major cause of the unsatisfactory durability can be related to the high hygroscopicity of wood and the great difference in hygro-thermal properties between the components, resulting in wood-polymer de-bonding. In addition, mechanical processing (e.g. sawing, sanding and planing) of wood in general forms a weak boundary layer of loose and crushed wood cells in the surface which also may interfere with the wood-polymer bonding.
The main objective of this work was to study ultra violet (UV), or excimer, laser irradiation on wood as a means to remove, by ablation, the outer deformed layer from a wood substrate. Effects of the UV-laser treatment on wetting and liquid permeability characteristics were studied by Wilhelmy plate experiments, and effects on the wood surface chemistry were studied by X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (TOF-SIMS). The micromorphology of wood was studied by low vacuum-scanning electron microscopy (LV-SEM).
The pre-treatment of wood substrates by UV-laser ablation resulted in a notable changes in surface micromorphology, liquid permeability, wettability and surface chemistry characteristics.
Keywords: laser ablation, micromorphology, permeability, wettability, surface chemical composition
Authors
Bryne L.E.
KTH, Royal Institute of Technology, Building Materials, Stockholm, Sweden
Lausmaa J.
SP Technical Research Institute of Sweden, Chemistry and Materials Technology, Borås, Sweden
Ernstsson M.
Institute for Surface Chemistry, Stockholm, Sweden
Englund F.
SP Trätek, Technical Research Institute of Sweden, Wood Technology, Stockholm, Sweden
Wålinder M.E.P.
SP Trätek, Technical Research Institute of Sweden, Wood Technology, Stockholm, Sweden
Söderström O.
KTH, Royal Institute of Technology, Building Materials, Stockholm, Sweden
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