Thermal modification (TM) is the most important commercial modification procedure. TM wood has improved durability, but its performance does not meet expectations predominately under moist conditions. To reduce water uptake of TM wood, Norway spruce specimens were treated with suspensions of a natural wax by dipping or by vacuum-pressure impregnation. Wax treated specimens were subsequently thermally modified at 185, 200, 215, and 230°C. Control specimens were heated up to 100°C only. Contact angle (CA), short-term and long-term water uptake, bending strength and performance against wood decay fungi of the resulting material were determined. The results show that a combination of wax treatment and TM have a synergistic effect that considerably improves hydrophobicity, reduces liquid water uptake, slows down water vapour uptake, and improves the resistance against fungal decay of the treated material.
COBISS.SI-ID: 2601097
The use of wood in outdoor, above-ground applications is increasing in Europe. To further increase wood usage, more information related to service life and maintenance costs must be provided. Water exclusion efficacy (WEE) is one of the most important factors influencing service life and strongly correlates to wood moisture dynamics, surface properties, and hydrophobicity (WEE as a whole). WEE can be improved with modifications and hydrophobic treatments. The aim of this study was to elucidate which wood surface properties affect WEE and to note changes over time caused by artificial or natural aging. Wood samples of oak (Quercus), sweet chestnut (Castanea sativa), European larch (Larix decidua), Scots pine heartwood and sapwood (Pinus sylvestris), Norway spruce (Picea abies), and beech (Fagus sylvatica) were used to investigate this phenomenon. The moisture performance of the wood samples was improved with thermal modification, wax, oil, and biocide treatment. In total, 17 materials were prepared. After treatment, four different aging procedures were applied. Before and after aging, Fourier transform infrared spectra, colour, and contact angle were determined. The analysis of untreated wood based materials indicated that durability and hydrophobicity are related. Of all the treatments, wax performed the best and retained high hydrophobicity even after the most severe aging method (outdoor exposure).
COBISS.SI-ID: 2555017
A relatively new approach for wood protection against fungal decay is based on hydrophobisation of wood and on lowering its moisture content. Water repellence of wood can be increased by polymerization of hydrophobic monomers in wood cell walls. It was found out that Norway spruce wood after treatment with octadecyltrichlorosilane (OTS) exhibited reduced water uptake by the wood cell walls, lowered water vapour sorption, and significantly increased dimensional stability of wood in terms of anti-swelling efficiency. Hydrophobicity and lower equilibrium moisture content were shown to cause increased resistance of the treated samples against brown-rot decay and molds.
COBISS.SI-ID: 2593417