Research Articles

Pyrolysis of biomass residues can generate savings in the value chains of forest products due to the potential uses of its products in the forestry sector. The aim of this study was to determine the performance during slow pyrolysis process and the yields of different products of two types of residues, wood chips and solid wood board-ends from Gmelina arborea. Results showed no significant differences in yields of charcoal (26 to 28%), wood vinegar (28 to 30%) and non-condensable gases (37%), but bio-oil yield was higher for the solid wood board-ends residues (7.7%). The evaluation of energy charcoal characteristics and wood vinegar was similar for two types of residues.  So, results suggest that two types of residues provided similar charcoal, condensable and non-condensable gases yields, but solid board-ends are recommended to obtain higher yield of bio-oil and complete the process in less time. Charcoal and vinegar characteristic were affected by type of residues.

The storage stability of binders before their application is a crucial factor in the wood panel industry, as it impacts the mechanical properties, quality control, economic efficiency, and market competitiveness of the final products. In the present study, the long-term stability of two canola protein isolate (CPI) and two canola meal (CM) adhesive variants was investigated. The protein-based adhesives were prepared and tested on one-layer particleboards after one week, one month, two months, three months, and four months of storage of the formulations. Results indicate that the CPI-based outperformed the CM-based variants in terms of internal bonding strength (IB), modulus of rupture (MOR), and modulus of elasticity (MOE) due to the higher protein concentration of the CPI over the CM. While the IB strength of the CM-bonded particleboards was lower than the EN 319 requirement after the first four weeks of storage (0.34 N/mm² and 0.29 N/mm² for nitrite and bisulfate-crosslinked respectively), that of the CPI-bonded was still superior to the EN 319 after four months (0.44 N/mm² and 0.3 N/mm² for nitrite and bisulfate-crosslinked respectively). This indicates that the nitrite-crosslinked variants had a more robust chemical formulation, leading to stronger and more durable bonds.

As hardwood cross-laminated timber (CLT) gains attention due to its construction potential, understanding the interaction between hardwood panels and adhesives is critical for ensuring structural integrity and longevity of buildings. This study investigated adhesive bonding properties in hardwood CLT made from red oak (Quercus spp. L.), sweet gum (Liquidambar styraciflua L.), and yellow poplar (Liriodendron tulipifera L.), using southern pine (Pinus spp. L.) (SP) as a control. Adhesive performance was evaluated through shear block tests to assess the bond line shear strength and delamination tests to measure the bond durability under cyclic moisture conditions. Results indicated significant variations in adhesive performance among the hardwood CLT specimens compared to SP, with differences in both shear strength and delamination resistance. Red oak CLT exhibited significantly greater delamination compared to all the other species. The delamination observed among the yellow poplar samples was not significantly different than that of the control SP samples. The shear block results indicated that the bond line strength of both red oak and yellow poplar samples was significantly greater than that of the control samples. These findings provide critical insights into selecting and optimizing adhesives for hardwood CLT production.

This paper presents an analytical modeling approach to predict the effective in-plane and out-of-plane thermal conductivities of laminated wood composite products such as Cross-Laminated Timber (CLT). Considering wood’s orthotropic nature, having models that could be used to estimate the effective thermal conductivity properties of laminated wood products in various directions becomes essential for understanding the coupling between mechanical and thermal properties, as well as predicting the dimensional stability of large wood composite panels. For this purpose, analytical thermal conductivity equations were derived in three orthogonal directions, considering different properties of wood along its orthotropic directions, following Fourier’s Law. The derived equations were then applied to different CLT panel products and results were compared to assess their accuracy. As CLT panels may be produced without edge gluing, two scenarios were investigated to understand the effect of edge gluing on thermal conductivity of such panels. First, the presence of adhesive between timber layers was ignored (i.e. not edge-glued panels); second, adhesive and its thickness were included. Results demonstrated the reasonable accuracy of the proposed approach in predicting the thermal conductivity of CLT panels made with different gluing methods. The modeling of imperfect bonds and air gaps is also briefly discussed.

The antimicrobial and tyrosinase enzyme inhibition activities of various extracts and isolated compounds of Limonium meyeri were investigated. Apigenin-7-O-β-glucuronide and myricetin 3-O-α-rhamnoside were isolated from the ethyl acetate fraction using chromatographic methods. Methanol extract showed 62.0% and ethyl acetate extract showed 57.6% tyrosinase enzyme inhibition activities at 400 µg/mL concentration. Myricetin 3-O-α-rhamnoside (IC₅₀ = 27.7 ± 0.6 µg/mL) showed higher tyrosinase enzyme inhibitory effect than apigenin-7-O-β-glucuronide (IC₅₀ = 43.0 ± 0.9 µg/mL). n-Hexane extract was found to be effective against Enterococcus faecalis (MIC = 1 µg/mL), while methanol extract was effective against Pseudomonas aeruginosa (MIC = 16 µg/mL). Myricetin 3-O-α-rhamnoside showed antimicrobial effect against Enterococcus faecalis (MIC = 128 µg/mL). Thus, Limonium meyeri and its compounds may provide valuable insights for future studies as antityrosinase and antibacterial agents.

Mechanical and physical properties were determined for laminated Scots pine (Pinus sylvestris L.) using polylactic acid (PLA). Structural parts were produced via 3D printing with additive manufacturing (FDM: fused deposition modeling) method in the middle layers. For this purpose, PLA parts with 30%, 60%, and 90% filling rates were glued to the middle of the 5-layer laminated material with polyurethane (PU) glue, and physical and mechanical tests were conducted according to the relevant standards. It was found that increasing the filler content resulted in higher density, reduced water absorption and thickness swelling, increased bending strength and modulus of elasticity, while screw holding resistance increased by approximately 75%. Compressive strength parallel to the fibers showed comparable results to control samples. These findings suggest that PLA filler particles can serve as an alternative middle layer material in wood lamination, offering potential for minor but meaningful improvements in specific applications.

The shift of wood raw material sources from natural forests to community forests opens opportunities for West Java Province Indonesia as a source of wood raw materials because it has a large area of community forests. One type of plant grown in community forests is the jabon tree (Neolamarckia cadamba). This study will investigate whether jabon wood can be utilized as raw material for wood composite, such as laminated veneer lumber (LVL), laminated veneer board (LVB), and plywood, from the aspect of physical and mechanical characteristics, such as moisture content, density, bending strength, hardness, delamination, and formaldehyde emission. Another will find out the economic consideration of jabon compared with sengon wood. Results showed that based on the physical, mechanical, delamination, and formaldehyde emission characteristics, the tested jabon wood can be used as a raw material for wood veneer-based composite with better characteristics compared to sengon wood.  However, the availability of jabon wood is lower than sengon wood and the price of jabon wood was higher than sengon wood. These factors may limit jabon utilization.

The accumulation and allocation of heavy metals—arsenic (As), strontium (Sr), palladium (Pd), and vanadium (V)—were measured in Pinus nigra wood over more than three centuries. Contrary to expectations, the results did not show a correlation between increasing air pollution in recent decades and the concentrations of these metals in annual rings. Thus, P. nigra wood appears unsuitable as a biomonitor for tracking long-term heavy metal pollution in air. However, metals deposited in specific annual rings remained restricted within those rings, supporting the hypothesis of limited radial migration over time. The study specified P. nigra as a promising candidate for phytoremediation due to its capacity to accumulate high concentrations of As, Sr, Pd, and V. Additionally, these metals exhibited robust positive correlations with other toxic elements (tin, antimony, niobium, silver, thallium, selenium, and lead), suggesting that P. nigra could serve as an indicator of regions with multiple heavy metal pollutants. These findings highlight the complexity of metal uptake and allocation processes in trees and underscore the need for further research in controlled environments to clarify mechanisms of metal transfer and toxicity. Despite its limitations relative to its usage as a biomonitor, P. nigra demonstrated potential for mitigating heavy metal contamination in polluted environments.

In recent years, lignin analysis utilizing quantitative nuclear magnetic resonance (qNMR) has attracted considerable interest and has been the subject of numerous studies. However, evaluating the measurement uncertainty of qNMR results of lignin remains a challenge. Specifically, uncertainty originating from lignin sampling or subsampling has been overlooked in a large majority of articles. Although lignin is a reasonably homogeneous substance, it is nevertheless a solid, and individual samples collected from the same bulk may have somewhat different compositions depending on mixing and the amount of sample taken. The objective of this study was to evaluate the influence of sampling uncertainty on qNMR analysis of lignin-based analysis as a case study, with an exclusive focus on the relative quantification method. The results from this study demonstrate that sample-to-sample variations can contribute to approximately half of the variability in actual qNMR measurements. The relative standard deviation (RSD) of sample-to-sample variability was 2.4%. In contrast, the other sources of variability related to qNMR, including measurement, baseline irregularities, and partial peak overlap, caused an RSD of 4.4%. The total variability RSD was 5.0%. In this article, two calculation approaches were presented for evaluating the uncertainty due to sampling from replicate measurement data of different samples, which may be helpful for practitioners in the field.

The effect of alkali lignin on laccase activity and mycelial biomass of Flammulina velutipes was investigated under different fermentation temperature. The secretion of laccase by F. velutipes has certain specificity. Specifically, laccase activity could not be detected by F. velutipes CCMSSC 00103 under most fermentation medium, but could be detected by F. velutipes FL 19 under more fermentation medium. Among the three strains of F. velutipes, the laccase secretion capacity of F. velutipes FL 19 was obviously better than that of F. velutipes CCMSSC 05331 and F. velutipes CCMSSC 00103. Maximum laccase activity with the value of 73.42 ± 4.74 U/L was secreted by F. velutipes FL 19 in fermentation medium 2 appeared at 2th day. The presence of alkali lignin was useful for improving laccase activity secreted by F. velutipes and the effect of alkali lignin on improving laccase activity exceeded that of Populus beijingensis. F. velutipes were more suitable for secreting laccase at 26 ℃ due to the maximum laccase activity measured at 26 ℃ (73.42 ± 4.74 U/L) higher than that measured at 33 ℃ (70.71 ± 6.89 U/L). The results were useful for selecting suitable medium and temperature of F. velutipes strains to produce low-cost laccase.