Considerable efforts have been made to replace formaldehyde-containing adhesives in the manufacturing of wood products, particularly particleboard, with natural alternatives. One promising solution is the liquefaction of lignocellulosic materials such as wood using glycerol (C₃H₈O₃) under sulfuric acid catalysis (H₂SO₄). The aim of this study was to investigate the chemical composition and properties of spruce and oak biomass after liquefaction and to evaluate its potential as a formaldehyde-free adhesive substitute. All samples were liquefied at 150 °C for 120 min in five different wood–glycerol ratios (1:1 to 1:5). The liquefaction percentage, the insoluble residue, the dry matter and the hydroxyl (OH) number were determined as characteristic values for the polymer properties of the liquefied samples. The results showed the liquefaction percentage was up to 90% for spruce and oak. The insoluble residue ranged from 10 to 29% for spruce and from 10 to 22% for oak, the dry matter ranged from 54 to 70% for spruce and from 51 to 62% for oak, while the highest xydroxyl number was 570 mg KOH/g for spruce and 839 mg KOH/g for oak. Based on these results, liquefied wood was shown to be an effective natural alternative to synthetic resins in particleboard adhesives and a way to reduce formaldehyde emissions. This research not only supports environmentally sustainable practices but also paves the way for various bioproducts derived from liquefied biomass and points to future avenues for innovation and development in this area.

Using the RadSawSim simulator for radial sawing, a simulation of the radial sawing technique was used to saw Pedunculata oak (Quercus robur L.) logs. Simulation was implemented with a view to producing as many radially sawn boards as possible and took into account the influences of increasing volume yield, lumber value yield, and log-value yield. The methods that were analyzed were live sawing and radial sawing of third sections, fourth sections, fifth sections, and sixth sections of the log. Live sawing achieved the best results of volume yield during simulation, which was followed by radial sawing into the third, fourth, fifth, and sixth sections. The difference in volume yield with live sawing compared to the radial-sawing method is very large for logs up to a diameter of 45 cm. It becomes smaller when the log diameter is greater than 45 cm. A comparison of the radial method shows that the share of radially sawn boards and lumber value yield increased when the number of log sections during sawing simulation increased. If log-value yield is assumed to be the main criterion, and given the conditions used in this simulation, there is no justified reason to saw logs using the radial technique when the diameter is less than 45 cm. The live sawing technique is more efficient for these diameters of logs, and, therefore, the radial sawing technique is more efficient for logs with a diameter greater than 45 cm.

Black alder (Alnus glutinosa (L.) Gaertn.) wood is characterized by rapid and frequently non-uniform color changes after felling and during hydrothermal processing. These changes are largely associated with extractive compounds, among which oregonin, a phenolic diarylheptanoid glycoside, has been identified as a precursor of the characteristic orange-red coloration. However, information on the thermal stability of oregonin remains limited. This study investigated the effect of temperature and exposure time on oregonin content in black alder bark extract. Aliquots of the extract were exposed to isothermal conditions of 30, 40, 50, and 60 °C for up to 24 h. In a separate trial, a treatment at 98 °C was conducted to simulate the temperature conditions associated with wood saturated water steaming at atmospheric pressure. Oregonin concentration was determined using reversed-phase high-performance liquid chromatography with diode-array detection. Oregonin content remained comparatively stable during 24 h exposure at 30, 40, 50 and 60 °C, with reductions of 6.00%, 3.00%, 2.78%, and 1.64%, respectively, without clear increase in oregonin loss with increasing temperature. Exposure to 98 °C resulted in the most pronounced decrease in oregonin content, with a reduction of 43.93%. The results indicate comparatively high stability of oregonin during 24 h exposure at 30–60 °C, whereas a pronounced decrease was observed in the separate aqueous treatment at 98 °C. These findings are relevant for understanding chemical changes in alder extractives during wood drying and steaming and demonstrate the importance of minimizing unnecessary heat exposure during sample preparation, extraction, and storage.