Wood Science and Technology最新文献

Consolidation has always been a major conservation issue for waterlogged archaeological wood (WAW), which aims to prevent shrinkage and cracking upon drying. Here we developed a new organic solvent-free consolidation method using water-soluble amino silanes and dialdehydes, which involves versatile cross-linking processes between wood components and polysiloxane. Evaluations by shrinkage measurements after air-drying, Fourier transform infrared spectroscopy, static thermal dynamic analysis, and dynamic vapour sorption suggest the combination of N-(2-aminoethyl)-3-aminopropyltrimethoxysilane and glutaraldehyde provides the most satisfying dimensional stability, mechanical strength and hygroscopicity. The anti-shrinkage efficiency reached as high as 96.9% for highly degraded WAW of Catalpa sp. after air-drying. The bending strength was increased to approximately 4 times and the elastic modulus was increased by around 10 times. The described method provides a new solution for the consolidation and dehydration of WAW, which produces excellent dimensional stability in lab-scale trials after air-drying without using organic solvents. However, studies are required on the long-term stability of the materials and durability of the treated WAW against microbial and chemical degradation before it can be applied in practice.

Wood density is a crucial property indicator for construction material selection, quality assessment, and modification. Spectral analysis techniques and chemometric models offer potential solutions for the rapid and non-destructive assessment of wood density. However, probe-contact spectroscopy has low efficiency in spectrum collection, and spectral models are highly specific to variations in instruments and samples. Traditional calibration transfer methods are diverse and struggle to adapt to domains with significant distributional differences. By simulating operations under natural light, this work aimed at exploring a deep transfer-learning strategy, facilitating the transfer of wood density prediction models between different instruments [from portable near-infrared (NIR) spectrometers to hyperspectral-imaging (HSI) imagers] and among tree species (two softwood and two hardwood species). A bidirectional gated recurrent unit plus attention layer (BiGRUattention) was employed as the basic topology for the deep network. The results indicated that the generalization ability and robustness of HSI model transferred by deep adversarial transfer-learning strategy, including domain-adversarial-neural Network (DANN) and dynamic-adversarial- adaptation network (DAAN), surpassed traditional calibration transfer and deep transfer-learning methods, achieving a level comparable to NIR-calibrated models. DAAN based on Wasserstein distance with gradient penalty (WgpDAAN) optimized model accuracy, convergence speed, and stability. The deep adversarial transfer-learning model could be adapted to wood spectral data from different instruments and tree species, where WgpDAAN significantly reduced modeling costs and enhanced productivity, and could be extended to detecting and characterizing other wood properties.

This study aimed to investigate the effects of mineral impregnation on fir wood using magnesium-based compounds. Two methods, combination and separate treatment, were used to impregnate heat-treated and non-treated samples. The Bethel method, involving vacuum and pressure, was employed for the impregnation process. The impregnated samples underwent assessments for weight gain, volumetric bulking, water soaking tests, water droplet contact angle, mechanical properties, and fire resistance. Additionally, SEM and EDAX analyses were conducted to evaluate the changes in the wood structure pre- and post-impregnation. The findings revealed the filling of pores and cavities in certain areas with Sorel cement, particle accumulation in cell walls and cell lumina, and an increase in the presence of Mg, Cl, and O elements in the impregnated samples. Furthermore, the physical property analyses indicated improved wood properties post-impregnation, with the combination impregnation method demonstrating the most notable performance in terms of weight gain percentage. Electron microscopy confirmed the formation of the magnesium oxychloride cement structure within the cell voids of both types of wood. The mineralization of the wood structure with magnesium compounds resulted in increased dimensional stability, reduced water absorption, and enhanced bulking and density of the wood. Moreover, the contact angle of water droplets on the wood’s surface decreased following impregnation with magnesium compounds, while the surface roughness of the wood increased. Mineral impregnation significantly enhances the bending strength, modulus of elasticity, impact resistance, and fire resistance of wood, regardless of heat treatment. The combined impregnation method consistently outperforms the other method.

Strand characteristics, i.e. orientation, length, width, and size, have a substantial effect on the mechanical properties of Oriented Strand Board (OSB). In this study, an automatic method was established to obtain the characteristics of the strands on the surface layer of the OSB mattress in real time by taking images and using neural networks. The Segment Anything Model was used to extract surface layer strands, the YOLOv5 model was used to distinguish and position strands, and the minimum bounding rectangle algorithm was used to measure characteristics of each strand. Based on the results obtained from manual measurement, the performance of the automatic method was evaluated. In laboratory tests, this method presents great performance in extracting and distinguishing characteristics of strands. This method also shows good adaptability for production line application. In the production line, around 80% of strands can be correctly extracted and distinguished, with a strong correlation between manual measurements and automatic method results (R² > 0.97). It takes 37.7ms to process one image containing approximately 500 strands. Strand orientation in the production line nearly concords with normal distribution (N (-1.25, 30.5²)). The size of strands significantly affects the relative intensity of the strand orientation (with P < 0.05). There is a positive and linear relationship between the strand size and the orientation of strands. The outputs of this study contribute to a better understanding and management of OSB manufacture in the production line.

This work examined the chemical interrelations between melamine–formaldehyde (MF) and waterlogged archaeological wood to demonstrate the effect of the MFtreatment on cultural heritage objects. Samples from a Roman waterlogged trunk of Greek fir, were analyzed with Fourier Transform Infrared Spectroscopy (FTIR), solid-state ¹³C Nuclear Magnetic Resonance (NMR), analytical pyrolysis with in-situ silylation Py(HMDS) coupled with Gas Chromatography Mass Spectrometry (GC/MS) and Evolved Gas Analysis-Mass Spectrometry, (EGA-MS) before and after the MFtreatment. FTIR results showed the formation of amide functionalities due to melamine reactions and strong evidence of lignin modification, while the deteriorated cellulose fraction appeared to have undergone further depletion as a result of the MF treatment. The ¹³C NMR spectra of the MF-treated wood clearly demonstrated the presence of the resin within the wood and indicated that MF carbons were strongly interacting with lignin moieties. Spectra also revealed that the retention of the MF resin in the wood was positively correlated to the degree of wood degradation. Py(HMDS)-GC/MS of MF-treated wood provided few peaks attributed to holocellulose or lignin pyrolytic products, and it was not possible to detect any signs of non-MF-modified wood components, as the lignocellulosic wood matrix appeared to have been transformed into a new biopolymer. EGA-MS profiles of the MF-treated archaeological wood showed early evolution of volatiles due to free MF retained in the wood, while its thermal stability appeared increased in comparison to untreated material. Nonetheless, mass peaks indicated that the chemistry of MF-treated wood was completely different from both fresh and untreated deteriorated wood. Overall, results showed that the MF treatment irreversibly modified the residual chemistry of the archaeological material and failed to preserve its original physical and historical integrity. This permanent modification of unknown longevity is considered not in line with conservation ethics and, therefore, inappropriate for the long-term preservation of cultural heritage objects.

Sawdust from deciduous trees was used as a raw material for the preparation of carbonaceous adsorbents. Microwave-assisted chemical activation with K₂CO₃ and H₃PO₄ was used to produce materials with a well-developed porous structure. The obtained activated biocarbons were characterized in terms of their porous structure, elemental composition, morphology, thermal stability, as well as surface and electrokinetic properties. The sorption abilities of both materials towards synthetic (poly(acrylic acid)) and natural (lysozyme) polymers in the process of their removal from aqueous systems were determined. Both single adsorbates and mixed solutions of two polymeric adsorbates were tested. The stability of aqueous suspensions containing activated biocarbons and one or two polymers was also determined. As a result of microwave-assisted chemical activation two carbonaceous adsorbents were obtained, characterized by a very well-developed specific surface area (1093–1777 m²/g), a completely different type of porous structure (mesoporous or microporous), and the acidic nature of the surface. The maximum adsorption of poly(acrylic acid) was obtained from a mixed solution of both polymers and it reached values of 379 mg/g (for the sample activated with H₃PO₄ with mean pore diameter 3.04 nm and minimal contribution of micropores—0.3%) and 259 mg/g (for K₂CO₃ activated material characterized by the mean pore diameter equal to 1.72 nm and large contribution of micropores—77.4%). In the case of lysozyme, the adsorption efficiency was two times lower (sorption capacity of 127–166 mg/g). Based on the collective data analysis, it can be stated that the most probable mechanisms of polymeric destabilization (highly desirable in separation from the multicomponent solutions) are surface charge neutralization at pH 3 and bridging flocculation at pH 11 (especially for the systems containing material activated with H₃PO₄ and poly(acrylic acid)).

Wood adhesion is one of the fundamental joint technologies for wood-based materials. We focused on an unprecedented chemical bonding wood adhesion. With the final goal of water-resistant wood adhesion using dicarboxylic acid compounds with straight alkyl chains, this study clarified the difference of adhesiveness between glutaric acid (GA) and citric acid (CA) to explore the direct effects of chemical bonding type adhesion on physical properties. In the prepared wood-based moldings, the structural analysis with 2D-NMR of the interphase between GA or CA and wood surfaces revealed that GA adhesion is cleaner and more reactive than CA adhesion, without any side reactions. GA reacted with the wood powder surface. In addition, the water resistance treatments of the GA-type wood-based molding showed a thickness reversibility that is not observed with CA-adhesion. The results indicate that GA-adhesion is very likely a chemical bonding type of wood adhesion, considering the molding process under high temperature and pressure conditions. The physical properties of the molding were evaluated to determine the adhesion properties. GA-type wood-based molding was tougher and more water-resistant than CA-type wood-based molding. The physical properties were attributed to the side-chain structure of GA. The results indicate that dicarboxylic acid compounds could be superior wood adhesives, and other dicarboxylic acids could be used for wood adhesion and the expression of material properties owing to their various side chain structures. Furthermore, the material properties could be controlled by considering the chemical structure of adhesive compounds in the future.

Acetylation is a wood modification method that reduces the hygroscopicity of wood and increases its resistance to degradation by wood decaying fungi. Even though acetylated wood can have very high decay resistance, the wood material can be degraded and sometimes deacetylated by fungi. This study investigated the degradation and deacetylation of acetylated wood by Coniophora puteana and Rhodonia placenta to better understand the relationship between degradation and deacetylation in two different brown rot fungi. Wood samples were exposed to the fungi in a stacked-sample decay test, followed by acetyl content measurements and FTIR spectroscopy to investigate chemical changes in the samples. The results showed that both fungi could degrade acetylated wood to high mass loss despite a strong reduction in moisture content, but only R. placenta was found to cause preferential deacetylation. The deacetylation was slight and only observed in the early stages of decay in highly acetylated wood. Otherwise, acetyl groups were lost from the samples at the rate of mass loss. FTIR spectroscopy confirmed the loss of acetyl groups and revealed some chemical differences between unacetylated and acetylated wood. The spectral data indicated the loss of acetyl groups from lignin, which suggests that the loss of acetyl groups is not only due to the degradation of acetylated carbohydrates. The degradation of acetylated wood required further investigation, but it is clear that extensive deacetylation is not a requirement for brown rot degradation.

Four new peltogynoid monomers (3, 7, 10, 11) and a new peltogynoid dimer (9) were isolated from the heartwood of Peltogyne mexiacana, along with six known compounds (1, 2, 4, 5, 6, 8). Among the known compounds, the absolute configurations of two flavanones (5, 6) were determined. The structures of the isolated compounds were determined using NMR and MALDI-TOF MS analysis. The discoloration of the methanol solutions of the isolated peltogynoids and flavanones was examined by exposing them to room light in the air. The methanol solutions of (+)-peltogynol (1) and (+)-mopanol (4) discolored to reddish and bluish purple, respectively. After discoloration, the b* values of these compounds decreased significantly from 12.1 to 19.1 to -0.7 and − 1.8, respectively. These precursors of pigment compounds 1 and 4 have a catechol moiety in the B ring, and a hetero-six-membered ring (D ring) connecting the B and C ring of flavan-3,4-diol via an oxyethylene bridge, which is similar to the structure of leucoanthocyanidin. These results led to the hypothesis that the metabolized pigment compounds have anthocyanidin-like structures with peltogyne skeleton.

Wood is an important construction material, but a significant problem hindering its widespread use is susceptibility to biodeterioration and biodegradation. To protect wood against degradation, a surface coating can be used, and it is important to be able to predict the ability of the coating to prevent fungal growth. The currently available standard method to determine the antifungal efficiency of a coating has two weaknesses, viz. no evaluation of the moisture content in the wood material, and no possibility to study antifungal effect of the coating towards an individual fungus. A new quantitative method of determining the antifungal efficiency of coatings is therefore proposed, where a coating is applied to wood and exposed to an individual fungus in a Petri dish. Six commercial water-based coatings containing synthetic biocides were studied on filter paper (EN 15457) and with the new test method on wood blocks. The results show the importance of studying the antifungal efficiency of a coating using individual fungi instead of a mixture of fungi, since individual fungi interact differently with a given biocide in the coating. The moisture content of the wood substrate during the test was affected by how the fungus was established on the coating. This new test approach shows promise in screening the antifungal efficiency of wood coatings containing preservative substances applied to wood material surfaces.