Pleating is an optimal way to increase bendability of wood used in diverse industrial applications. It results in the excessive buckling of cell walls and modifications of constitutive polymers. However, thoughtful understanding of the physical–chemical mechanisms of that modification process is very limited. The main purpose of the present study was to identify changes in functional groups of wood polymers induced by longitudinal compression. Four types of wood samples prepared from beech and sessile oak (untreated, steamed, longitudinally compressed and fixated for 1 min as well as longitudinally compressed and fixated for 18 h) were assessed by infrared spectroscopy. The spectra interpretation revealed that changes can be observed in hydroxyl as well as in carbon–oxygen single and carbon-hydrogen functional groups of polysaccharides and lignin. Beech wood seems to be more susceptible to investigated modification processes as compared to oak. Detailed interpretation of infrared spectra allows identification of changes in the hygroscopicity of wood as well as alterations in the linkage between structural elements in the polymer matrix of wood induced by the applied treatments.Graphic Abstract

Since the properties of wood significantly change with its moisture content, it is important to know the effect of different moisture conditions on wood. A brief summary is provided on this topic in the first part of this article. The compression along the wood grain is a modification resulting in better pliability. The moisture dependence of mechanical properties of longitudinally compressed wood is not known yet. For this purpose, the results in this article are considered as basic research results. Bending- and compression tests on beech specimens compressed longitudinally by 20% were carried out at different moisture contents. Changing moisture content has almost no significant effect on the modulus of rupture of wood that has been longitudinally compressed, compared to the sensitivity to changes in moisture content of untreated wood. However, the effect of moisture content on the change of bending modulus of elasticity, compressive strength parallel to the grain and bendability coefficient diverges significantly. As a result of these changes, there is a great difference in the pliability with different moisture contents of treated wood. For the best pliability during bending, the moisture content of longitudinally compressed wood must be close to its fiber saturation point.

Colour Stability of Thermally Modified Wood during Short-Term Photodegradation

In this work, the effect of oil heat treatment (OHT) on the swelling properties and changes in the rate of moisture uptake of poplar wood (Populus × euramericana cv. Pannónia) were investigated. Eighteen different treatments (combinations of three vegetable oils, two temperatures, and three durations) were studied. The results showed that OHT decreases the equilibrium moisture content (EMC) and the swelling of poplar wood. The degree of swelling and the EMC are influenced by both the duration and temperature of treatment. With an increase in duration and temperature, the EMC decreased. Consequently, the anti-swelling efficiency (ASE) increased. OHT wood adsorbs less moisture than natural wood, but it reaches a maximum – EMC at the momentary climate – at the same time under all the investigated treatments. The moisture uptake is fastest in the beginning and thereafter it slows significantly. Decreasing the moisture uptake by OHT wood is due to the decreasing of its water storage capacity.

One of the goals of the European Union’s agroforestry plans is to alleviate the shortage of timber in Europe caused by the growing demand for hardwoods and the declining import of tropical timber. The study shows which tree species can be considered in agroforestry systems in Europe, and which of them can be used as raw material for the wood industry and what quality of wood can be produced in agroforestry systems. Since 2005, the European Union has been officially encouraging farmers to plant the crops in an agroforestry system and parallel try to produce trunks for high quality timber. By analysing the current economic developments of the European Union, especially Horizon 2020, our study provides an overview of what can be expected by the participants of the agroforestry sector and the related primary wood industry in the European Union now and in the future. In addition to the distribution analysis, indices describing projects have also been created. Rank correlation was used to examine the relationship between them. Possible decision mechanisms were also outlined using a custom-built expert software system.