The utilization of natural raw materials has been practiced for centuries. Of raw materials, wood and its bark have outstanding significance because of their special chemical components and unusual structure. Annual bark production is estimated to be between 300 and 400 million m3. The bark of different tree species has been used extensively in or in conjunction with modern technologies. This article presents a comprehensive summary of these methods of utilization and their results. The diversity of bark utilization derives from the variety of the bark of different species and from the possibilities encoded in the material. Following the anatomic summary, the protective role of the bark is discussed, highlighting its physical-chemical properties and the different methods of medical, energetic, and industrial utilization.

The lignin, cellulose and hemicelluloses in wood are polymers that behave similarly to the artificial polymers and are bonded together in wood. Lignin differs from the other two substances by its highly branched, amorphous, three-dimensional structure. Under appropriate conditions, the moist lignin incorporated in the wood softens at about 100 °C and allows the molecules of it to deform in the cell walls. There are many advantages and disadvantages to this phenomenon. If we know this process accurately and the industrial areas where it matters, we may be able to improve these industrial processes. This article provides a brief theoretical summary of lignin softening and the woodworking processes where it plays a role: wood welding, pellet manufacturing, manufacturing binderless boards, solid wood bending, veneer manufacturing, and solid wood surface densification.

No abstract

No abstract

In terms of reduced energy consumption and simultaneously promoting woody biomass sustainability, researchers are seeking energy-efficient materials, originating from forestry and agricultural residues, for application in the building sector. In this study, bark-based panels overlaid on both surfaces with three different fibreglass types and two types of paper sheets were evaluated for potential utilization as thermal insulation panels. The proposed panels were then characterized regarding their thermal conductivity, physical, and mechanical properties such as density, water absorption, thickness swelling, surface soundness, bending strength and modulus of elasticity. It was found that thermal conductivity values ranged from 0.067 to 0.074 W/(m K) for all the produced panels. As suggested from the results, fibreglass overlays exhibited improved performance compared to paper sheet overlaying. In addition, the fibreglass overlaid bark-based panels displayed promising characteristics as insulation materials. Finally, fibreglass woven fabric was found to be more beneficial than the mesh and mat fibreglass types.

No abstract

As wood products in use store carbon and can contribute to reducing the concentration of atmospheric CO2, the improved and enhanced use of wood products can be a successful measure in climate change mitigation. This study estimates the amount of carbon stored in the Hungarian harvested wood product (HWP) pool and the CO2 emissions and removals of the pool. According to our results, the total carbon stock of the Hungarian HWP pool is continuously increasing. We estimated the total carbon stock of the HWP pool to be 17,306 kt C in the year 2020. Our results show that the HWP pool in Hungary is a carbon sink in most parts of the time series, with some years where it turns to a source of emissions. We carried out a simple projection up to 2070, assuming a constant inflow for the projected years that is equal to the average inflow of the last five historic years. This resulted in a decreasing trend in CO2 removals, with removals already very close to zero in 2070. We concluded that in order to achieve significant future carbon sinks in the HWP pool technological improvements are needed, such as increasing the lifetime of the wood products and expanding the carbon storage capacity of wood products by reusing and recycling wood in a cascade system.

This research involved the most widely used wood-species of veneers in Hungary (oak, ash, beech, cherry, and maple). The resulting changes in color produced at treatment temperatures between 80 and 200 °C in different treatment times were evaluated using the CIELab color stimulus evaluation system. For higher temperature treatments, a tight functional relationship was observed between the treatment time and the difference in color stimulus. Heat treatments within a temperature range above 160 °C produced visually perceptible results, while color change resulting from heat treatments at lower temperatures was almost imperceptible. For higher temperature treatment a tight functional relationship was observed between the difference in color stimulus and treatment time (r 2 >min. 0.84). Different tree species produced different extents of change in hue depending on the treatment parameters. Among the color components, the perceptible discoloration was mostly produced by the change in the lightness factor (L*). As the treatment temperature rose, the change in the red (a*) and yellow (b*) components was less significant regardless of the species.