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Abstract: This study investigates the dynamic mechanical properties of flexible polyurethane (FPU) adhesives bonded to European beech wood (Fagus sylvatica L.) using Dynamic Mechanical Analysis (DMA) over a range of temperatures and frequencies. Samples included clear beech wood and three-layered composite (beech:FPU:beech). DMA tests were performed using a three-point bending setup at 1 Hz and 10 Hz in the temperature range from -120°C to 140°C. The results demonstrated high thermal stability and strong bonding performance of FPU adhesives on beech wood. Frequency-dependent responses varied among FPU types but resembled the behavior of solid wood at lower temperatures. This confirms the suitability of DMA for evaluating adhesive-wood composite behavior under dynamic conditions. The combination of FPU adhesives and beech wood showed potential for thermally stable and energy-dissipating bonded assemblies.
Keywords: dynamic mechanical analysis, FPU, beech wood
Published in DiRROS: 27.08.2025; Views: 338; Downloads: 161
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Abstract: As part of the »ULTRA – University of Ljubljana for a Sustainable Society« project, a new test method was introduced into the curriculum to provide insight into key properties that affect wood durability. This study aimed to adapt and verify the “paste test”, which uses wood dust in nutrient media to assess the inhibitory effect of wood components on fungal growth. The method was adapted to match the available laboratory equipment and simplified for educational use by students at the Department of Wood Science and Technology (Biotechnical Faculty, University of Ljubljana, Slovenia). The study involved testing fungal growth on nutrient media supplemented with spruce wood dust, with the goal of evaluating different grinding methods, nutrient media, and data analysis. Potato dextrose agar nutrient media was confirmed as a suitable alternative to malt extract agar. The wood dust fraction size had no significant effect on fungal inhibition, enabling the use of coarser, less time-saving grinding methods. Image analysis and logistic growth modelling were conducted using freely available software (ImageJ and R-Commander), which proved to be effective alternatives to proprietary tools. Visualization of growth using logistic growth rates offered a clearer comparative analysis, despite some loss of dynamic growth information.
Keywords: inhibition, wood chemistry, nutrient media, white rot fungi, brown rot fungi, logistic growth rate
Published in DiRROS: 15.07.2025; Views: 628; Downloads: 236
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Abstract: European beech Fagus sylvatica and Sessile oak Quercus petraea are reaching the north-eastern limits of their natural ranges in northern Poland. According to the projected changes in potential ranges in this region, climatic conditions for both species until 2080 will remain stable. On the other hand, a decrease in the vitality of mature trees and a reduction in their radial growth are currently observed. To understand these contradictory findings, we monitored the cambial activity in both species during two vegetation seasons. 2015 was characterized by a negative water balance, while 2017 was wet. This provided an opportunity to compare how the xylogenesis proceeds in diffuse-porous beech and ring-porous oak during contrasting in the summer precipitation seasons. The forming annual increments were sampled with Presler borer at variable time intervals depending on the leaf phenological phases. The cores were prepared using a sledge microtome and double-stained with safranin and astra blue. Observations of the phases of wood formation and measurements of the width of the forming increments were analysed on the microslide digital images. Differences in the dates of the phenological phases were analysed using Two-Way ANOVA, while the dynamics of the formation of annual increments were fitted to the Single and Double Gompertz function for beech and oak, respectively. The beginning of vessel formation started earlier in both seasons compared to previous studies. Inter-seasonal differences in the duration of spring phenological phases were insignificant for both species, while inter-species differences were significant due to physiological diversity between diffuse-porous beech and ring-porous oak. In dry 2015, cambial activity ceased sooner in both species than in 2017. Differences between oak and beech were insignificant in both years, but statistically significant disparities existed within each species due to varying in precipitation seasons. Rainfall significantly elongated the duration of cambial activity and caused wider tree-rings. According to our study, despite predicted maintaining their climatic niche, both species, situated at the north-eastern cooler range boundary, are expected to produce wood at a lower rate due to the projected warmer central European climate with increased heatwaves and summer droughts.
Keywords: climate change, meteorological extremes, wood formation, summer drought, xylogenesis
Published in DiRROS: 08.07.2025; Views: 409; Downloads: 308
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Abstract: Growing concerns about indoor air pollution heighten the need to develop depolluting materials to achieve a healthy built environment. This study developed functional coatings for wooden surfaces using 20 wt% photocatalytic biocarbon particles doped with manganese oxide (BC–MnO2) and two different coating materials (linseed oil and waterborne acrylic). The samples' surface hydrophobicity and color properties were tested before and after accelerated aging. The depolluting potential of the samples was evaluated by formaldehyde removal efficiency test in indoor conditions. Results showed that adding BC-MnO2 particles increased the hydrophobicity regardless of the coating material's type. After accelerated aging, the hydrophobicity of all samples increased, which was attributed to the curing of the oil and acrylic polymers and the increase in surface roughness eventually caused by surface damage. The color change (ΔE) was more intense in the case of uncoated wood and samples without BC-MnO2. However, the BC-MnO2-containing coatings were effective in color preservation (ΔE < 2), which was attributed to the anti-UV property of biocarbon. The BC-MnO2-containing coatings exhibited a promising formaldehyde removal efficiency of up to 24 % and 46 % for oil and acrylic samples, respectively. The combination of BC-MnO2 and acrylic material was more favourable to attracting the formaldehyde molecules, likely due to the similar polarity. The developed functional coatings exhibited an acceptable ability for wood protection and formaldehyde remediation and can be potentially used to enhance indoor air quality.
Keywords: photocatalytic wood coating, hydrophobic surface, UV protection, volatile organic compound, formaldehyde removal
Published in DiRROS: 30.01.2025; Views: 862; Downloads: 496
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Abstract: The wood-based bioeconomy is one of the main pillars of sustainable transformation and decarbonisation of the economy, as it promotes the use of renewable resources, reduces reliance on fossil fuels, and supports the development of eco-friendly industries. The paper provides quantitative insight into the potential impacts of transformation of the wood-based bioeconomy in Slovenia, a small, export-oriented economy with ample, but sub-optimally used, forest resources. The analysis uses an input–output (I-O) model to estimate I-O multipliers of sectors representing the wood-based bioeconomy and to capture their direct and indirect impacts on the Slovenian economy. The baseline performance of the wood bioeconomy sectors and their potential to induce economic activity (Scenario A) are estimated with an adjusted I-O model (based on the national I-O table for 2015), in which hybrid sectors are divided into conventional and bio-based segments. Alternative transformation pathways are translated into four additional scenarios. While Scenario B foresees progress in efficiency and integration within the existing structure of transactions, Scenario C (increased energy use of wood biomass) and Scenarios D/D+ (technology- and capital-intensive restructuring) represent two extreme restructuring pathways of the sector. The results of scenario analysis with the I-O model show that the changes in the input requirement structure of the Slovenian wood-based bioeconomy could result in up to a 17% increase in total output, up to a 20% increase in the number of employees, and up to a 16% increase in incomes, all of them attributed to the most optimistic scenario (D+). The results of the study provide quantified assessments underpinning strategic planning for the wood-based bioeconomy, both in the industry and public policy spheres.
Keywords: wood-based bioeconomy, input–output model, transformation pathways, impact analysis, strategic planning
Published in DiRROS: 09.01.2025; Views: 658; Downloads: 428
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