Volume 78, Issue 11-12

To evaluate the inheritance of natural durability of Acacia mangium Willd., wood-color parameters ( Y [lightness], x [red to green], and y [yellow to blue]), mass loss by a white-rot fungus ( Trametes versicolor ) and brown-rot fungus ( Fomitopsis palustris ), and three different extracts (methanol extract, total phenol, and total flavanol content) were measured using the inner and outer heartwood of 10-year-old trees from 20 half-sib families in the third-generation A. mangium in Indonesia. The broad-sense heritability ( H 2 ) values were moderate to high for the wood-color parameters and mass loss by white- and brown-rot fungi ( H 2 = 0.210–0.851) and low to moderate for three different extracts ( H 2 = 0.000–0.576). Significant negative phenotypic correlations were found between the three different extracts and mass loss by T. versicolor and F. palustris . In addition, negative correlations were found between the wood-color parameters and three different extracts. Similar results were found between the total phenol content and y and between the total flavanol content and Y in genetic correlations. Therefore, A. mangium families with lower Y and y in heartwood could produce progenies with higher total phenol and total flavanol content, leading to higher natural decay resistance.

Taxodium ‘Zhongshanshan’ is a distinctive tree known for its rapid growth and robust stress resilience. To enhance the utilization of forestry resources, tannin extracts were procured from the barks (BE) and leaves (LE) of Taxodium ‘Zhongshanshan’. The tannin structures were characterized by FT-IR and MALDI-TOF MS, and found to be condensed tannin with a degree of polymerization not exceeding 6. The tannin extracts exhibited a potent ability to scavenge free radicals at capacities of 60–80 % compared to Vitamin C (VC). They inhibited the bacterial strains Escherichia coli ( E. coli ) and Staphylococcus aureus ( S . aureus ), with a pronounced effect on the latter. Furthermore, tannin from Taxodium ‘Zhongshanshan’ appears benign and have no significant effect on cell activity.

While chemical modification enhances wood’s resistance to deterioration and dimensional stability, it often results in alterations to the mechanical properties, limiting its engineering applications. This study focuses on the in situ esterification of beech wood using malic acid/polyol mixtures and evaluates its impact on mechanical properties. The results of the compression tests yielded limited information, characterized by a notable degree of variability as indicated by the high standard deviation. The four-point bending tests conducted here revealed an increase in the modulus of elasticity (MOE). However, this improvement in MOE was accompanied by a decrease in the modulus of rupture (MOR), indicating a trade-off between stiffness and strength. To better understand the mechanisms affecting the treated wood’s mechanical properties, we compared the experimental and theoretical glass transition (Tg) of the polymers with material stiffness. X-ray computed tomography revealed that treatment increases specimen density and creates a gradient, with higher density near the surface, potentially contributing to increased stiffness. These findings suggest a nuanced impact of the in situ esterification process using malic acid/polyol mixtures on the mechanical properties of beech wood.

The characterization of the wood behavior at the tissue scale is still scarcely explored compared with the macroscopic scale, especially for shear. This work focuses on the mechanical properties of tissue samples of Norway spruce ( Picea abies ). Tensile and shear tests were conducted in different anatomical directions and relative humidity (RH) levels. The results provide insights into the distinct behaviors of early- and latewood and their combination within growth rings, showing the significant impact of RH on performance.

StExCell, a novel sulfur-free and chlorine-free biorefinery concept, based on mild steam explosion followed by mild caustic extraction, oxygen delignification and bleaching, is introduced to produce dissolving pulp for textile application. Steam explosion of Betula pendula at 210 °C for 7 isothermal min (equivalent to a P-factor of ca. 1,250), combined with a total-chlorine-free purification sequence resulted in a fully bleached pulp with only 3.6 % xylan, a slightly wider cellulose molar mass distribution and a higher pulp yield, while consuming only about half of the chemicals, in reference to a prehydrolysis-kraft process. The chemical recovery and valorization of the extracted wood component were not covered by the scope of this work but speculated to be simpler than in a kraft process.

Acetylation is a breakthrough in wood modification and has been established on industrial scale. However, concerns have been raised regarding the stability of acetylated wood under elevated temperatures, particularly during post hot-pressing processes to manufacture products such as laminated veneer lumber (LVL). At around 150 °C, the added acetyl groups might cleave off (“de-acetylation”) and by that release sorption sites for water. This would increase the moisture uptake of the modified wood. In this study, the impact of hot-pressing at 150 °C on the stability of acetylated beech veneers and LVL was investigated. Fourier transform infrared (FTIR) spectroscopy showed that the chemical composition of acetylated veneers seemed to be unaffected after the heat treatment. Dynamic vapor sorption (DVS) analysis and long-term storing over saturated salt-solutions in miniature climate chambers, indicated no de-acetylation on the basis of negligible changes in wood-water interactions. The number of hydroxyl groups of heat-treated acetylated samples was similar to that of not heat-treated ones, indicating the persistence of the effects of acetylation. By the present study, a certain resilience of acetylated wood towards elevated temperature, like it may occur during hot-pressing of acetylated veneers, became apparent and illustrated the thermal stability of this chemical modification approach.

To produce biogenic phenolic-rich liquids, which could be of great interest to the adhesive, wood preservation and coating industry, beech wood slow pyrolysis liquid (SPL) was extracted with supercritical CO 2 (scCO 2 ). To this end, a scCO 2 extraction plant was extended with a separation unit with three separators. A stepwise depressurisation of the scCO 2 in the separators enabled various fractions of the extracted SPL, with differing compositions, to be collected. During depressurisation, the density of the scCO 2 (724 kg/m 3 –2 kg/m 3 ) and, thus, the solubilities of the extracted substances in scCO 2 were reduced in three separators. At a density of 261 kg/m 3 in the second separator, extracts with a content of up to 41.1 wt.% GC-detectable monomeric phenolic substances were produced. At lower scCO 2 densities in the subsequent separator, the proportion of better scCO 2 -soluble substances, such as acids, ketones and furans, increased in the extracts.

Wood modification processes based on citric acid in combination with various copolymers have gained in importance in recent years. These processes also include modification with citric acid (CA) and sorbitol, a sugar alcohol, which is currently in the industrial realisation phase in Germany (SorCA) and Norway (CIOL). The modification of wood with sorbitol and citric acid (SorCA) can significantly improve the dimensional stability and durability of the wood. It is hypothesised that the addition of a copolymer may improve the fixation of the chemicals within as well as the flexibility of the modified wood matrix. In this study, the macroscopic changes, the fixation of the chemicals and the impact bending properties of wood modified with CA and SorCA are compared. Both modifications cause a permanent increase in mass (WPG) and volume (CWB). The fixation of the chemicals was comparable for both modifications; at high chemical concentrations, the SorCA polyester fixed slightly better within the wood matrix. Both modifications led to embrittlement of the wood, measured by a decrease in the impact bending strength (IBS). This embrittlement was clearly concentration-dependent and slightly more pronounced for the modification with CA.

In this study, the feasibility of hydrophobizing pine wood veneers through gas grafting with palmitoyl chloride using a hot press was explored. To achieve this, the hydrophobization characteristics of wood veneer were analyzed under various conditions, including pressing temperature, time, and concentration of palmitoyl chloride. The results showed that the gas grafting treatment successfully hydrophobized the pine wood veneer, and that the pressing temperature and concentration of palmitoyl chloride were the main factors influencing the grafting. The hydrophobization efficiency increased with an increase in the pressing temperature and palmitoyl chloride concentration, whereas the pressing time had little effect. However, under conditions of excessively high palmitoyl chloride concentration, pressing temperature, and excessively long pressing time, relatively large color changes and a pH drop in the veneer were observed. Therefore, it was concluded that to treat pine wood veneer with a diluted solution of 0.5 % palmitoyl chloride at 180 °C for 6 s was appropriate.

Calamus balasaeanus Becc., a climbing palm species, has potential commercial value. Detailed anatomical and chemical analyses of rattan stems at different ages are crucial for their utilization in various industrial applications, particularly eco-friendly products. In this study, rattan stems of different ages were examined using light microscopy, transmission electron microscopy, and Fourier transform infrared spectroscopy. The results showed that the anatomical structure of rattan stems at different ages are very similar, with vascular bundle sizes ranging from 0.26 to 0.37 mm and a frequency of 8.4 to 13.7 bundles/mm 2 . The vessel lengths and diameters were 1.87–2.35 mm and 0.10–0.16 mm, respectively. Fiber lengths and diameters were 0.84–1.15 mm and 8.65–11.55 μm, respectively. As C . balasaeanus matured, the secondary wall of fiber cells thickened into the cell lumen, changing from 2 layers to 4 layers, the amount of crystallinity in cellulose increased while the mean microfibril angle decreased. The crystallinity of cellulose was higher in the periphery of the stem compared to the center. Unimodal imaging effectively visualized the distribution of various polysaccharides in C. balasaeanus tissues, with the highest concentrations of cellulose, hemicellulose, and lignin found in the base of the rattan stems.

This paper deals with value addition and utilization of Lantana camara , an invasive species with unprecedented rate of growth, by thermal modification. Lantana camara stalks were thermally modified using vacuum heat treatment (VHT), oil heat treatment (OHT), and steam heat treatment (SHT) at 180 °C and 200 °C and subsequently changes in physical, chemical and mechanical properties were studied. Weight loss was observed in vacuum and steam heat treated samples due to thermal degradation while oil heat treated samples showed weight gain due to oil uptake. SHT exhibited the highest (19 %) weight loss at 200 °C. The color of the modified lantana attained uniform dark colour, OHT exhibited the most intense effect on colour changes. Fourier transform infrared (FTIR) and Fourier transform near infrared (FTNIR) spectroscopic analyses indicated degradation of hemicellulose and change in cellulose crystallinity due to heat treatment. Dimensional stability of thermally modified Lantana stalks improved across treatments, with SHT achieving the highest anti-swelling efficiency of 67.3 % at 200 °C and lowest water absorption (43 %) after 72 h of water soaking. The dynamic modulus of elasticity of thermally modified Lantana remained constant in all the treatment processes. Overall, the results indicate that thermal modification can increase utilization potential of L. camara .