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Preservative systems based on vegetable seed oils and natural waxes from renewable sources may confer protection to wood under exposure to various environmental conditions. These, as non-toxic substances, can form an environmentally friendly and efficient protective layer on the wood surfaces, with beneficial effects on their water resistance and dimensional stability. Thus, these natural coatings may hinder biodegradation of wood products to a certain degree. In present paper, softwood samples (from Abies alba fir tree species), prepared as dried discs (25 to 30 mm diameter, 8 to 10 mm thickness), were surface impregnated by dipping using vegetable oils, namely Asclepias syriaca seed oil, and soybean oil, respectively. Beeswax treatment was also applied for comparison purposes. Surface chemistry and morphology, biodegradation process under controlled and simulated natural conditions, and water sorption behavior of wood samples were investigated. Fourier Transform Infrared spectroscopy, X-ray diffraction, and scanning electron microscopy methods were used for investigation of surface changes in wood samples before and after impregnation with natural based products, as well as under biodegradation conditions in soil burial tests.

Wooden structures are becoming increasingly popular in the construction world. However, these structures often rely on synthetic adhesives, raising concerns about the environmental risks associated with their chemical composition. In response to these concerns, this study aims to explore sustainable alternatives, particularly focusing on polyurethane adhesives that incorporate proteins from industrial byproducts. The investigation involved three protein sources: soybean meal, shrimp shells, and skim milk, modified under mild alkaline conditions to obtain protein concentrates. These concentrates were then incorporated into the adhesives at varying protein contents: 5%, 10%, and 15%. Additionally, two isocyanate systems were examined, one being petrochemical-based and the other a partially bio-based blend. Chemical, thermal, optical, and mechanical characterizations were conducted to evaluate the adhesive performance. This study demonstrates that the adhesives’ thermal properties remain unaffected by both the protein content and the isocyanate system. However, these factors influence the adhesive penetration into the wood substrate. Ultimately, the results suggest that higher protein content offers superior retention of mechanical strength in adhesives compared to the petrochemical reference when subjected to humid conditions. Overall, this research demonstrates the potential of proteins from industrial byproducts as sustainable adhesive allies, providing valuable insights into their interactions with different isocyanates.

Laboratory and field experiments were performed to examine the feasibility of using Time Domain Reflectometry (TDR) to monitor moisture content (MC) of wood and standing trees. The TDR was used to detect the electromagnetic wave propagation time of four tree species (Betula platyphylla, Tilia tuan, Picea asperata, and Fraxinus mandshurica) at different MCs. During the TDR test, effects of probe insertion depths on MC predictive accuracy were considered. The best results were obtained at an insertion depth of 8 cm. At the selective 8 cm insertion depth, a species-specific MC prediction model (0.94 ≤ R2 ≤ 0.98), a generalized model for the four species (R2 = 0.65), and a hybrid model for the species with similar densities (0.80 ≤ R2 ≤ 0.96) were constructed, respectively. Overall, the species-specific MC prediction model showed good predictive ability for both tree and wood disc samples, including that TDR can be used to detect wood and standing tree MC. If possible, the hybrid model can be used for species with similar density.

Wood structures generally rely on synthetic adhesives for their strength and versatility. However, environmental concerns linked to the chemical composition of these adhesives have stimulated the search for more environmentally friendly adhesives. Researchers have explored replacing petroleum-based constituents with natural raw materials such as lignins, tannins, and proteins. Of these alternatives, proteins, being biological macromolecules, are recognized for their capacity to enhance adhesion to wood substrates. This study considered the development of protein-based adhesives derived from diverse sources, including soybean meal, microbrewery spent grains, shrimp shells, and skim milk powder. These raw materials were subjected to mild alkaline conditions to yield protein concentrates. The resulting adhesives were formulated at various protein content levels: 5%, 10%, 15%, and 20%. The study's findings showed that the incorporation of proteins into the polyurethane adhesive system not only can preserve but also augment adhesive performance. This enhancement encompasses deeper penetration into wood substrates and an overall improvement in mechanical strength. These results underscore the promise of proteins as a sustainable alternative to petroleum-based polyols in adhesive formulations.

Using phase change materials (PCMs) is an efficient solution for reducing energy consumption in buildings. These materials have a large capacity for storing thermal energy, making them an appealing option for energy management purposes. Phase change materials have been successfully incorporated into various construction materials such as concrete, brick, or plaster. The primary objective of this review is to examine previous studies conducted on the application of PCMs in wood. The initial section presents an overview of the direct impregnation techniques utilized for wooden materials. This is followed by a discussion on the implementation of macroencapsulated PCMs in wooden structures that are typically present in residential buildings. In addition, the use of shape-stabilized PCM/wood composites, preventing potential leaks during the phase change transition, is explored. Finally, patents related to the use of PCMs in wood are described. Future challenges include the incorporation of PCMs into wood composites to improve their thermal properties. This literature review shows that there is a gap in knowledge regarding the utilization of phase change materials in wood-based panels such as oriented strandboards, fiberboards, and particleboards. This provides an opportunity for future research to improve the performance of the products manufactured by the wood-based panels industry.

The purpose of this study was to determine the effect of four different age groups on wood properties, i.e., anatomical, physical, and mechanical, of Himalayan birch (Betula alnoides Buch.-H.ex D.Don). The correlation between the properties was also discussed. The results indicated age influences the anatomical, physical, and mechanical properties of Himalayan birch. Results were comparable with other plantation species. Moreover, mechanical properties were highly correlated with the fibre morphology in Himalayan birch. Results from this present study indicate that the 15-, 20-, and 25-year-old Himalayan birch are suitable to be used for parquet, furniture, and other products. Generally, plantation-grown Himalayan birch has the potential to be a raw material to fulfill the demand for the timber industry.

With the application of bleaching treatments, the color of the wood material changes. When different bleaching agents are applied to the same wood, different results are likely to be obtained. In this study, wood species doussié (Afzelia africana), iatandza (Albizia ferruginea), merbau (Intsia bijuga (Colebr.) O. Kuntze), mahogany (Swietenia mahagoni L.), and hornbeam (Carpinus betulus L.) along with one and two component (B-One-C and B-Two-C) wood bleaching chemicals were applied to the wood material surfaces with sponge technique. Then, color parameters (ho: hue angle, a*: red color tone, b*: yellow color tone, C*: chroma, and L*: lightness) were determined on bleached and unbleached materials. According to the results obtained, B-One-C application increased ho, a*, b*, C*, and L* values in all wood species. The highest ∆E* values were determined in mahogany, doussié, hornbeam, and merbau wood species treated with B-Two-C. The chemicals used in the study showed different results on the same wood.

As a typical orthotropic material, the mechanical properties of wood in the parallel and perpendicular-to-grain directions are very different. Based on mathematical orthogonality, mechanical force balance condition, and energy comparability, the deformation energy decomposition method of planar wood element is proposed, and then the quantitative and visual analysis of the basic deformation performance of wood structure is realized. The basic deformation performance of wood structure and isotropic structure is analyzed using the deformation energy decomposition method, and the seismic performance of wood frame structure and concrete frame structure is compared. The results show that the lateral resistance and beam ductility of wood frame are greater than those of concrete frame under seismic load. However, the reduction of deformation energy proportion of wood frame beam leads to greater deformation energy of the frame column, so it is suggested to take targeted strengthening measures to the bottom of the wood frame column and the joint area.

This review article discusses the use of organosilane (OS) compounds and their derivatives to modify wood materials. The emphasis in this work is on trialkoxysilanes and effects of their reactions with hydroxyl groups at wood surfaces. The versatile properties of OS make them ideal for improving the water resistance, weather resistance, antibacterial properties, and dimensional stability of wood. This article provides an overview of recent techniques and methods used to modify wood substrates with OS, highlighting the main findings and advancements in the field. Additionally, the article suggests future research directions, including innovative modification mechanisms, strategies to control the pollution caused by biomaterial-based silanes, and the investigation of the influence of wood permeability on silane modification.

Currently, there is a big issue with waste, its processing and subsequent use. While there are many initiatives to replace materials that are poorly biodegradable, it is necessary to process and ideally use the waste that is already produced. In this study, the properties of composite boards made of waste materials and biodegradable polymer were investigated. The composite boards were made from wood and plastic waste using high-energy milling technology. This technology for material preparation is promising, as it includes controlling the morphology of particles, homogenizing the mixture, and drying the material during the milling process. The results showed higher flexural strength of high-density fiberboard (HDF) boards compared with tested composites with one exception. Wood/poly(3-hydroxybutyrate-co-3-hydroxyvalerate) [PHBV] composite exhibited 30% higher modulus of elasticity (MOE) than HDF due to the higher modulus of PHBV. The lowest thickness swelling (3%) and water absorption (12%) were measured for wood/recycled high density polythene (rHDPE) composite. The HDF boards recorded the lowest dimensional stability. The highest water absorption of tested composites was measured for wood/PHBV composite. The resistance to wood-rotting fungi was greatest for wood/PHBV composite containing marble powder, which corresponded to the results of scanning electron microscopy.

Despite the progress in synthetic polymer industries, wood is one of the main materials in making musical instruments because of its unique characteristics. Many instrument makers try to improve the acoustic properties of wood by traditional treatments. In this study, the changes in the acoustic properties of walnut wood during the processes of fermentation pretreatment, water washing, and organic solvent washings were evaluated. For this, the samples were divided into two groups of 20. For the first group, de-extraction was started with fermentation pretreatment, while the second group samples directly underwent stepwise extraction, using hot water and ethanol-acetone solvents. The results showed a decrease in density, dynamic modulus of elasticity, and damping factor due to the soaking process. But the elastic stiffness did not change. The values of the acoustic coefficient and the acoustic conversion efficiency increased due to the soaking process. The values of density, dynamic modulus of elasticity, elastic stiffness, and damping factor decreased due to ethanol-acetone washing, while the acoustic coefficient and acoustic conversion efficiency showed a significant increase. In general, soaking process and ethanol-acetone washing with fermentation pretreatment improved the acoustic properties of walnut wood.

In this study, the impregnation of a 3% solution of a mixture of medicinal aromatic plant extract, borax, and ferula plant extract on wood of eastern spruce (Picea orientalis L. (Link)) and mahogany were carried out and the changes in the anatomical structure of the impregnated wood were determined. Through obtaining extracts of various medicinal aromatic plants (ferula) and dual treatment with borax, the anatomical properties of wood material were examined and the related adhesion scale was determined. The highest retention (retention) was in mahogany wood borax (1.86%), and the lowest retention was again in mahogany wood ferula extract (0.31%). Both wood types demonstrated improved outcomes in comparison to the control sample when the air-dry and fully-dry specific gravity changes were investigated. The maximum air-dried specific gravity value was found in mahogany at 3% borax and ferula + borax (0.56 g/cm3), and the lowest at 3% ferula and borax (0.37 g/cm3). Mahogany wood with 3% borax had the greatest full dry specific gravity value (0.54 g/cm3), and spruce wood with 3% ferula and ferula + borax had the lowest (0.35 g/cm3). There was no retention in the tracheid and trachea cells that perform the transmission function. Because the sapphire cells are the cells that act as storage, adhesion has occurred in these cells.

The chemical modification of wood can be directed to improve various properties, e.g., the dimensional stability, hardness properties, and/or durability properties, against weathering. In this study, a Romanian softwood species Abies alba L. was treated and chemically modified using two cyclic acid anhydrides, i.e., maleic and succinic, to improve its interfacial properties relative to unmodified wood. Structural changes, with focus on the evolution of crystalline part in wood after chemical modification, the water absorption, and the water repellent efficiency, were determined. Maleic anhydride exhibited a lower reactivity towards wood substrate than succinic anhydride, presumably because of their different chemical structure (maleic anhydride is very sensitive to the presence of water). It was found that the percentage of water absorption was diminished, primarily after the succinic anhydride treatment. The chemically modified wood was characterized via Fourier transform-infrared spectroscopy and wide-angle X-ray diffraction methods. The crystalline part from wood structure was evidenced in relation to the employed anhydride in chemical modification approach.

Wood is a non-homogeneous and orthotropic natural polymer material. It is important to test the wood shear modulus and elastic constants accurately and reliably using dynamic methods. Based on the introduction of the advantages of six common methods for dynamic testing of wood shear modulus, such as free plate torsional mode method, free bar torsional vibration method, and Timoshenko beam iterative method, issues associated with the applicability and accuracy of these methods are also pointed out. Recent methods, such as the free square plate torsional mode method and the square plate static torsional strain method, that were developed to dynamically test the shear modulus of wood and wood composite materials, are presented as effective ways to tackle these issues. These new approaches are expected to provide beneficial technical support for using small specimens, overcoming the size effect of specimens, simplifying the testing procedures, improving the test accuracy, and expanding the application range in the dynamic testing of wood shear modulus. These approaches have practical significance in promoting the industrialization and development of structural engineering, furniture and interior decoration, transportation, military, and musical instrument industries.

Particleboard shear walls were developed and their lateral load carrying capacities were evaluated. The shear walls were made by connecting particleboards and timber studs with polyurethane (PUR) or nails. Seven types of particleboard shear wall specimens were manufactured by varying the wood species, size of the timber studs, and number of particleboards. The size of the shear wall specimens was 2.4 m × 2.7 m, and the bottom of the shear wall was fixed to the steel frame of the test equipment using hold-downs and angle brackets. As a result, the lateral load carrying capacities of the glued particleboard shear wall (73.4 to 75.6 kN/m) were 3.2 times higher than that of the typical light-frame shear wall and higher than the experimental data of the cross-laminated timber (CLT) wall in the CLT handbook. All glued specimens failed at the hold-down and angle bracket, and there was no damage at the glue layer between a particleboard and timber studs. The shear performance with different combinations of species, stud size, and number of particleboards was not significantly different, and the shear strength of the nailed specimen was approximately 20% lower than that of the glued specimen.

This study aimed to investigate the suitability of the interlaminar shear (ILS) testing method for veneer-based composites. The ILS testing method is an established method for composite materials as a qualitative evaluation of the adhesion within the composite. The applicability of this method to veneer based composites enables a simple qualitative statement on the adhesion of the individual layers. The ILS method complements existing wood-based material tests that focus on bonding, using significantly smaller material dimensions.

This research aims to optimize the comprehensive performance of wood-based electromagnetic shielding interference (EMI) materials and master the effect of heat treatment on its coating density, interfacial morphology, conductivity, and hydrophobic and electromagnetic shielding. The results showed that the surface roughness of composite coatings was 11.0 μm when the wood was conducted via electroless two deposition Cu and one Ni and the heat treatment temperature was 150 °C. The composite coating’s surface gradually became more uniform with increasing temperature. The coating’s thickness via 120 °C heat treatment was 97.5 μm. Energy Dispersive Spectroscopy (EDS) spectra verified the existence of Cu and Ni particles. The heat treatment had an obvious influence on conductivity of composite materials and the pore network structure. The contact angle of composite materials reached 119°. The average electromagnetic shielding efficiency via 180 °C heat treatment was up to 91.4 dB in the frequency ranging from 300 to 3.0 GHz, which verified that the composite materials can shield 99.99% of the incident electromagnetic wave energy. The conductivity gradient structure can realize multi-dielectric interface loss and multiple reflection loss.

Trees provide one of the most versatile biomass resources for many applications, namely wood. The chemical composition of wood determines its properties, being of real significance for its further capitalization, and depending on many factors. In nature, trees’ biomass is subjected to considerable pollution stress with further alteration of their normal growth conditions. Some correlations have been established between wood’s chemical composition and its further exploitation accordingly to particular circumstances of climate changes and pollution. The content of the main structural polymers from wood, cellulose and lignin, as well other components undergoes notable changes under the influence of pollution phenomena.

The color, texture, and natural defects of wood are important factors affecting its commercial value. Change of wood’s surface color is a primary way to improve its value. This study analyzes and summarizes the development status and existing problems of the traditional wood dyeing process and induced discoloration process. It is proposed that color improvement with photonic crystal structure color is a clean and pollution-free ecological biomimetic coloring technology. Its research status in the fields of fiber, fabric, wood, wood-based panel surface color improvement, new coatings for wood, and lignocellulose nanocrystalline structure color film are reviewed. The following aspects were studied: 1) construction and mechanistic study of the wood surface structure color film, 2) light response and interface mechanistic study of the wood surface structure color film, 3) large-scale application technology study of the wood surface biomimetic structure color film, and 4) preparation and functional development of structural color films of lignocellulose nanocrystal.

This study explored the potential of natural light to enhance wooden interior environments. Under Nordic light, natural materials such as wood finishes present an opportunity to create warm, bright, and pleasant atmospheres, enhancing psychological well-being and comfort. The objectives of this project were twofold: first, to study the diversity of northern sky conditions in terms of cloud cover and thickness, and, second, to evaluate the impacts of the diversity of natural light on five wooden scale models. The methodology involved weather data collection that took place during the spring equinox in Quebec City. In order to create a cloudiness scale, sky condition data and photometric measurements were collected. A photographic survey occurred in five scale models made with interior wooden finishes of varying color combinations, documenting the impact of sky diversity on brightness, hue, and contrast. Simultaneous scale model studies under a real sky allowed direct comparison under the same lighting conditions. There was a remarkable diversity of visual ambiences for a southeast-oriented space depending on the position of the sun and sky conditions. Gray-dyed wooden finishes created dull and unchanging atmospheres, while yellow oaked surfaces allowed various dynamic ambiences.

Wood easily acquires a large amount of moisture when it is exposed to high-humidity conditions. The high moisture content influences the service life of wood. Thus, there is a need for an accurate, rapid, nondestructive, and simple measurement technique for wood’s moisture content. This investigation proposes a method to measure the moisture content of wood by the wood volumetric heat capacity using a transient hot wire (THW) technique. The moisture content was inferred from the change of the volumetric heat capacity before and after the wood acquired moisture; the volumetric heat capacity is the ratio of the thermal conductivity to the thermal diffusivity. The results were validated by the gravimetric method, displaying good agreement, with discrepancies within 4%.

Many environmental advantages of wood in buildings have been thoroughly documented; however, this material’s effects on occupants are not well known or fully comprehended. This research aims to study comfort parameters in a multifunctional room characterised by extensive wood surfaces in comparison with a similar room with more conventional surfaces at Laval University, Quebec, Canada. The objectives of this research focus on determining the thermal, visual, and acoustical similarities and differences between two rooms using on-site surveys. Analysis of instrumental measurements and images of each room’s indoor environment under overcast skies determined the colour and texture of the surfaces. Quantitative and qualitative analyses revealed that both rooms share similar thermal and acoustic comfort parameters, but have contrasting visual characteristics. The colour, knots, and grain of the wood contributed to producing visually warm experiences resulting in a yellowish room, whereas a mix and match of artificial finishes generates a colder, bluish ambiance in the other room. The conclusion suggests that architects and designers should consider the indoor use of wood for its unique visual ambiances that enhance comfort levels.

Wood that is used in outdoor applications is frequently exposed to weathering and is thus prone to fungal degradation. Ways to prevent fungal degradation include keeping the wood dry. The majority of hydrophobic and wood modification systems have been tested only on freshly treated wood. Little information is available on how various wood-based materials perform after a certain period of weathering. To elucidate this question, 17 wood samples were tested from the following species: oak (Quercus), sweet chestnut (Castanea sativa), European larch (Larix decidua), Scots pine heartwood and sapwood (Pinus sylvestris), Norway spruce (Picea abies), and beech (Fagus sylvatica). Moisture performance of the wood samples was improved with thermal modification, wax, oil, and biocide treatment. Specimens were exposed to various degradation-aging factors (blue stain fungi, decay fungi, artificial weathering, and natural weathering). Various moisture performance tests were applied before and after aging: short-term water uptake (tensiometer), long-term water uptake, water vapor tests, drying tests, etc. The water exclusion efficacy of wood was decreased after aging. Aging factors were found to act synergistically and to have a more prominent influence on less durable wood compared to durable or preservative-treated wood. Wax-treated wood performed best, regardless of which moisture performance test was applied.

Prepared test specimens were surface treated and coated with synthetic and water-based outdoor varnishes after being chemically impregnated. The test specimens were left outdoors to determine the effects of impregnation and treatment on the wood during each of the four seasons. Caucasian spruce (Picea orientalis L.) test specimens were prepared and combustion analyses were performed. As a result of the combustion test, weight loss results, as compared with the control, were 89% lower in the spring specimens, 90% lower with impregnation, and 90% lower with the synthetic varnish coating. Furthermore, the O2 amount during combustion was found to be the highest in combustion with a flame source in the winter specimens (21%). The CO2 amount was the highest in combustion without a flame source for full-year specimens (20%). The CO amount was the highest in combustion without a flame source of full-year specimens (31,787 ppm), and the NO amount was the highest during glowing of full-year specimens (55 ppm). Final results showed impregnation with Tanalith-E and water-based varnish coating to be the most effective fire protective treatments.

Wood extractives, especially polyphenols, have great influence on the xylem colour of many wood species, which affects the success of hydrothermal wood processing, such as wood drying. One such wood species is European black alder (Alnus glutinosa (L.) Gaertn.), which is prone to forming intense and uneven reddish-orange or reddish-brown discolourations immediately upon harvesting and processing. However, there is lack of published scientific data on the wood and bark extractives of black alder, as well as the most suitable solvents to extract them. In this work, total soluble extractives, phenols, and flavonoids have been quantified in the wood and bark of black alder. Furthermore, the influence of four different polar organic solvents and deionized water on extractives removal yields has been measured. It was found that the bark has much higher levels of extractives as compared to the wood. Furthermore, it has been found that the highest extractive yields were obtained by using methanol as the extraction solvent for all observed compound group classifications.

This study investigated the effects of densification and heat post-treatment on the Janka hardness and microscopic structure of relatively low-density Uludağ fir, linden, and black poplar woods. Wood samples were densified with compression ratios of 25% and 50% at 100 °C and 140 °C, respectively. Heat post-treatment was then applied to the samples at 185 °C and 212 °C for 2 h. The hardness in the radial and tangential directions was determined, and morphological changes in the cell structures were analyzed using scanning electron microscopy (SEM). The hardness values in the radial and tangential directions of the densified samples increased depending on the compression rate and treatment temperature. The hardness values in both directions were higher in the 50% compressed samples. For samples compressed at 140 °C, the hardness values were higher in the tangential direction, whereas the samples compressed at 100 °C were higher in the radial direction. After the heat post-treatment process, the hardness values of all samples decreased. As the treatment temperature increased, more adverse effects on the hardness was noted. According to the SEM analyses, the densification and heat post-treatment deteriorated the cell structure of the samples. The more cell deformation was observed in the samples densified at 100 °C with compression ratio 50% and high heat post-treatment temperature.

Green fir wood (Pseudotsuga menziesii) was modified with polyethylene glycol (PEG) to produce wood composites for energy storage and conversion. The PEG-modified wood composites were evaluated based on their dimensional stability, durability, and thermal properties by various analytical methods. The differential scanning calorimetry (DSC) results showed the melting temperature and the latent heat of the phase change material (PCM) composite were 26.74 °C and 73.59 J/g, respectively. Thermal cycling tests and thermogravimetric analysis confirmed the composite exhibited good thermal stability, reliability, and chemical stability. All treated specimens were free from noticeable defects, and the addition of a surface varnish coating prevented PEG from leaching. The PEG-modified composites exhibited improved dimensional and thermal performance, which makes this material a potential candidate for economical and green, lightweight building materials.

A new deformation technique of wood flow forming is promising for industrial uses of solid wood. Flow deformability, size stability, and good mechanical properties were obtained by using wood impregnated with low molecular weight phenol formaldehyde (PF) resin. In this study, to clarify the effect of the PF resin and moisture contents in wood on the flow deformability (extrudability) and the mechanical properties of the product (extrudate), a lateral extrusion was conducted by using wood impregnated with various contents of PF resin and three levels of moisture content. The results indicated that the extrudability of wood impregnated with PF resin improved with an increase in both PF resin and moisture content. The mechanical properties of the extrudate worsened with increases in the moisture content of the wood impregnated with PF resin. Because most of the water in the wood remained in the mold during the extrusion process, chemical changes of the wood substance and PF resin occurred due to steam forming under the high temperature and pressure of the extrusion. The steam worsened the mechanical properties of the extrudate.

Laminated wood veneer lumber intercalated with rubber sheets (LLVR) was fabricated using a layered adhesive system composed of polyaryl polymethylene isocyanate (PAPI) for wood-rubber inter-bonding and phenol formaldehyde (PF) resin to glue the wood veneers. The optimized manufacturing process (chloroprene rubber: CR; PAPI: 80 g/m2; PF: 200 g/m2; and silane: 9.0 wt.%) was determined. The process as developed was then utilized to fabricate nine-ply LLVRs of five balanced constructions with two or three CR laminates used as various layers. The physico-mechanical properties of the LLVRs were evaluated, and the results showed that LLVRs had strong shear strength, sound dimensional stability, decent bending strength, and favorable toughening and buffering performances. The newly developed product is an interesting potential alternative to traditional laminated veneer lumber or plywood.

Mechanical properties of wood were evaluated using nondestructive test methods. The tests were conducted using the stress wave timing and resistance drilling machine, while static mechanical tests were conducted by an Instron universal testing machine. Both nondestructive and static mechanical tests were performed on wood specimens for Chinese fir (Cunninghamia lanceolata (Lamb.) Hook) and elm (Ulmus rubra). There were strong linear correlations between density (ρ) and resistance amplitude (F), static modulus of elasticity (MOE) and dynamic modulus of elasticity (ED), modulus of rupture (MOR) and ED, and ultimate compressive strength (UCS) and ED. Additionally, an algorithm of the reliability index was developed with the first-order second-moment method. The reliability analysis indicated that the reliability index increased with the decreased design value for both Chinese fir and elm, but it increased as the live-to-dead load ratio (ρ) increased. To achieve the reliability index requirements of the Chinese national code, the MOR design value should be set to 12.6 and 21.7 MPa, while the UCS design value should be set to 10.2 and 13.4 MPa for Chinese fir and elm, respectively.

This paper utilized 12 coating systems, based on an acrylate and a hydrophobic polymer, with the addition of light pigments, nano-sized polyvalent metal (AsS-chelate complex) for ultraviolet protection, and iodopropynyl butylcarbamate fungicide. This study deals with the impact of the number of coats on the color stability and the surface defects of painted black locust (Robinia pseudoacacia L.) and Norway spruce (Picea abies Karst L.) woods after up to three years of natural weathering, at a slope of 45°. The best coating system was created from three coats, which consisted of two pigmented acrylates (PerlColor) and one transparent hydrophobic water-repellent (AquaStop). The total color change, ΔE*, of the weathered surfaces was approximately two times lower when the application involved a pigmented coating system compared with a transparent one. The color stability of the surfaces and their resistance to defects was better when the coating system was applied to black locust wood compared with spruce wood. Smoother surfaces of wood before painting resulted in a higher resistance against cracking and other defects caused by natural weathering; however, the effect of the initial wood roughness on the color stability of painted woods during natural weathering was usually negligible.

The use of wood in outdoor, above-ground applications is increasing in Europe. To further increase wood usage, more information related to service life and maintenance costs must be provided. Water exclusion efficacy (WEE) is one of the most important factors influencing service life and strongly correlates to wood moisture dynamics, surface properties, and hydrophobicity (WEE as a whole). WEE can be improved with modifications and hydrophobic treatments. The aim of this study was to elucidate which wood surface properties affect WEE and to note changes over time caused by artificial or natural aging. Wood samples of oak (Quercus), sweet chestnut (Castanea sativa), European larch (Larix decidua), Scots pine heartwood and sapwood (Pinus sylvestris), Norway spruce (Picea abies), and beech (Fagus sylvatica) were used to investigate this phenomenon. The moisture performance of the wood samples was improved with thermal modification, wax, oil, and biocide treatment. In total, 17 materials were prepared. After treatment, four different aging procedures were applied. Before and after aging, Fourier transform infrared spectra, colour, and contact angle were determined. The analysis of untreated wood based materials indicated that durability and hydrophobicity are related. Of all the treatments, wax performed the best and retained high hydrophobicity even after the most severe aging method (outdoor exposure).

The crystallinity and acoustic-vibration parameters of Picea jezoensis, including specific Young’s modulus (E/ρ),coefficient of sound-radiation resistance (R), sound resistance (ω), and the ratio of Young’s modulus to the dynamic stiffness modulus (E/G), before and after heat treatment were measured and characterized. Conditions for the heat treatment included N2 as the protection gas and temperatures of 170 °C, 190 °C, and 210 °C with holding times of 2 h, 3 h, and 4 h. The results showed that specific Young’s modulus, the coefficient of sound-radiation resistance, and the ratio of Young’s modulus to the dynamic stiffness modulus increased, whereas sound resistance decreased, thereby improving the acoustic performance of the wood. The maximum increments were 5.7% for specific Young’s modulus (210 °C, 3 h), 8.8% for the coefficient of sound-radiation resistance (210 °C, 3 h), and 13.8% for the ratio of Young’s modulus to the dynamic stiffness modulus (210 °C, 4 h). Conversely, the maximum decrease in sound resistance was 5.6% (170 °C, 2 h). The crystallinity of heat-treated samples universally increased, and the maximum reached 60.67% (210 °C, 4 h), which was 9.9% higher than that of the control group. Moreover, the sound resistance decreased within increasing crystallinity growth, indicating that these two parameters were negatively correlated. Overall, the acoustic-vibration performance of P. jezoensis was improved through heat treatment, with the best vibration performance obtained at 210 °C with a holding time of 4 h.

The heat of combustion relative to the mass, Qm, was evaluated for 13 deciduous wood species, ranging from low to high density. The maximum and minimum values for Qm ranged, respectively, from 19.01 kJ⋅g-1 (Sd = 7 J⋅g-1) to 21.66 kJ⋅g-1 (Sd = 6 J⋅g-1) for Populus tremula and Alnus glutinosa wood. The average value of the Qm for all wood specimens evaluated in the present study was 19.93 kJ⋅g-1 (Sd = 706 J⋅g-1), which is 1.6% higher than the value reported in the literature (Krzysik 1975). A high correlation, R = 0.99, was observed between the volumetric heat of combustion, Qv, and wood density, D0. No correlation was discovered among Qm, D0, the ash content in the wood, ac, as well as the content of the following elements in the ash: calcium (Ca), potassium (K), magnesium (Mg), sodium (Na), silica (Si), aluminum (Al), iron (Fe), copper (Cu), manganese (Mn), sulfur (S), and phosphorus (P).

Recently, a processing technique resembling plastic-type forming has been developed for solid wood. To improve the recyclability of the formed products, thermoplastics were used as a binder. In this study, a hydrophobic monomer of methylmethacrylate (MMA) was used as a thermoplastic binder and was impregnated into wood, then polymerised by heat to form polymethylmethacrylate (PMMA). The effects of wood acetylation, a hydrophobising treatment of wood, on the extrudability of solid wood impregnated with PMMA (wood-PMMA composite) during extrusion were investigated. The acetylated wood was found to swell much more after the PMMA treatment than the untreated wood. The extrusion loads obtained from capillary fluidity tests of the acetylated wood-PMMA composite were lower than those of untreated composite. The fluidity improvement by acetylation can be attributed to a weakening of the cohesive interactions in the wood polymer, and this is primarily caused by the acetylation reaction itself. When the acetylated wood-PMMA composite was repeatedly extruded, the starting load of the extrusion decreased with increasing extrusion repetitions, probably as a result of decreasing wood particle size.

To test the hypothesis that wood coated with rutile TiO2 nanostructures can undergo degradation because of the photocatalytic activity of TiO2, three sets of wood specimens were aged at an accelerated rate. These three sets consisted of blank wood (BW), HDTMOS/MTMOS-coated wood (WHM), and TiO2/HDTMOS/MTMOS-coated wood (WTHM). After exposure to 155-h UV irradiation, the wettability of WTHM changed from hydrophobic to hydrophilic. This indicated that the initial low-surface free-energy materials underwent degradation because of the photocatalytic activity of TiO2. After exposure to 960 h of UV light irradiation and water spray, scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDXA) of WTHM showed that rutile TiO2 nanostructures had partially peeled off the wood surface. This suggested that the adjacent wood surface also suffered degradation because of the photocatalytic activity of TiO2. Although the rutile TiO2 coating noticeably enhanced the color stability during UV light aging, it made a relatively small contribution to the color stability of the wood during UV light and water spray weathering process. This study suggests that to derive the greatest benefit from modification of wood surfaces with rutile TiO2 nanostructures for weathering resistance, it is necessary to take measures to inhibit the photocatalytic activity of TiO2 or to fix the TiO2 coating on the wood surface.

Water plays a very important role in wood and wood products. The molecular motion of water in wood is susceptible to thermal activation. Thermal energy makes water molecules more active and weakens the force between water and wood; therefore, the water molecules dynamic properties are greatly influenced. Molecular dynamics study is important for wood drying; this paper therefore focuses on water molecular dynamics in wood through fast field cycling nuclear magnetic resonance relaxometry techniques. The results show that the spin-lattice relaxation rate decreases with the Larmor frequency. Nuclear magnetic resonance dispersion profiles at different temperatures could separate the relaxation contribution of water in bigger pores and smaller pores. The T1 distribution from wide to narrow at 10 MHz Larmor frequency reflects the shrinkage of pore size with the higher temperature. The dependence of spin-lattice relaxation rate on correlation time for water molecular motion based on BPP (proposed by Bloembergen, Purcell, and Pound) theory shows that water correlation time increases with higher temperature, and its activation energy, calculated using the Arrhenius transformation equation, is 9.06±0.53 kJ/mol.

Treating wood with impregnating materials in order to improve resistance to burning is a commonly employed safety measure. In this study, chestnut (Castanea sativa Mill.) wood samples were impregnated using either Tanalith-E or Wolmanit-CB according to ASTM-D 1413-76 and surface-treated using water-based or synthetic varnish according to ASTM-D 3023. These samples were used to investigate the combustion characteristics of samples left outdoors for one year as detailed in ASTM-E 160-50. The combustion temperatures of the samples left outdoors were similar upon impregnation with either Tanalith-E or Wolmanit-CB. However, the combustion temperature of the samples treated with synthetic varnish was lower than those that were treated with water-based varnish. The time to collapse and the total duration of combustion of the samples left outdoors were shorter for those impregnated with Wolmanit-CB. Weight loss of the samples left outdoors was higher for those that were impregnated with Tanalith-E and treated with water-based varnish. Gas analysis of the samples that were left outdoors indicated that the O2 content of flue gas from samples that were impregnated with Wolmanit-CB and treated with synthetic varnish was high and the CO content of flue gas from the same samples was low.

Chemical impregnation of black spruce was conducted to enhance the wood embedment capacity. The formulation was made of 1,6 hexanediol diacrylate, trimethylpropane triacrylate, and a polyester acrylate oligomer. A second formulation, same as the first but with 1% wt of SiO2 nanoparticles, was selected to investigate the potential of nanoparticles and to improve the efficiency of the treatment. The wood embedment capacity was carried out by a dowel-bearing test, which was performed for the two treatments and for an untreated wood group. Both treatments showed an increase of strength of nearly 50% when compared to untreated samples. Micrograph views revealed that the impregnation solution penetrated into the wood only up to 100 μm. Hence, with low chemical consumption, the structural bearing capacity can be significantly increased.

A study was carried out to assess the dust emission and working conditions in the bamboo and rubberwood furniture manufacturing industries in Malaysia. The emission of wood dust arising from these industries was measured in each main work station in the mills. Meanwhile, a questionnaire-based survey was conducted among 5900 workers in 45 companies to obtain information on the occupational accidents that occurred in the mills. The data were collected, compiled, and analyzed using the SPSS package. The highest dust emission from the sanding operation resulted in respiratory ailments among workers. The occurrence of injuries particularly to the hand, wrist, fingers and forearm was due to the prevailing working conditions, safety climate and workers characteristics. The dust exposure levels and working conditions were much more severe in the bamboo furniture manufacturing industry. As a result, a review of existing of dust exposure levels in the woodworking industry is warranted.

Woody tissues consist primarily of a mixture of cellulose, hemicelluloses, and lignin. Covalent bonds between lignin and polysaccharides likely play a central role in determining the mechanical and physical properties of wood. Intact and defined lignin-polysaccharide networks have not been isolated in large quantities because of the recalcitrance of lignin, which demands harsh chemical treatments that alter its structure. This report presents a method for preparing large quantities of lignin-polysaccharide networks similar to those naturally present in wood based on the enzymatic oxidation of hemicellulose from Norway spruce. Fungal enzymes produced from various carbon sources were used to depolymerize these networks. The method was used for simulating “enzyme mining” – a concept in biorefineries, giving a possible explanation for its mechanisms.

Moisture in wood acting as a plasticizer will strongly affect the wood’s viscoelastic properties. However, achieving the desired moisture content (MC) at elevated temperatures during creep tests is difficult. The aim of this study is to accurately and systematically investigate the creep behavior of birch wood at high temperatures. Experiments were conducted using a dynamic mechanical analyzer with a relative humidity accessory coupled with polyvinylidene chloride (PVDC) film for wrapping samples. Creep behavior was examined at six MCs (0%, 6%, 12%, 18%, 24%, >30%) and 11 temperatures (5 to 105 °C). The MC of wood was strictly and accurately controlled during creep tests. Instantaneous compliance (IC) and creep compliance (CC) increased with the increase of both temperature and MC, with significant changes at higher temperatures and MCs. The effects on IC and CC were more pronounced when the subject was influenced by MC, with readings approximately three times and one time greater than those influenced by temperature, respectively. Dramatic increases in CC were found at certain temperatures and MC values. There was a complex interaction between temperature and MC on IC and CC.

The feasibility of using near-infrared spectroscopy (NIR) to identify wood species was investigated in this study. Case I considers the principal component analysis scores plot of NIR spectra for three wood species. Case II considers whether NIR combined with partial least squares discriminant analyses can be used to identify the three wood species. Three wood species were studied, and each species included five randomly collected wood blocks, 21 samples for each wood block, and 315 total wood samples. In case I, the samples in the PCA analysis were clustered together. In case II, samples in the training set were classified into the correct group, and the accuracy of the test set was up to 90%.

Spruce and beech samples were irradiated by UV light in humid (100% air humidity) and dry conditions to clarify the effects of vapor on photodegradation. UV-irradiated samples were also soaked in distilled water for comparison. The color change and the IR absorption spectra were measured. The wet condition generated considerably greater discoloration than did the dry condition. The intensity of the color change was higher at elevated temperature (53 °C) than at 32 °C. The results showed that the presence of water as vapor increased the degradation of lignin. The nonconjugated carbonyl groups absorbing around 1760 cm-1 were found not to be stable, and the number of these chemical groups decreased in the presence of vapor when compared against the dry condition. The rising temperature amplified this degradation effect.

Interfacial compatibility plays a key role in the performances of natural fiber-reinforced composites. The measures commonly used to improve the interfacial compatibility focus more on the addition of various compatibilizers than on the structural modification of the natural fiber. In this paper, an attempt was made to enlarge the interfacial interaction areas of the recycled polyethylene (rPE)/wood flour (WF) composites by steaming the WF. Multi-monomer graft copolymers of polyethylene (GPE) were used as compatibilizers for the composites. How the enlarged interfaces affected the morphology, mechanical properties, water resistance, thermal stability, and dynamic rheological properties of the rPE/WF composites was investigated. The steaming process was able to enlarge the voids of the WF and therefore activate more interfaces for interactions. It was found that the interfacial morphology of the composites was affected by the degree of interfacial compatibility of the composites and so was characterized by various distinctive blossom shapes having a variation of compositions. With the help of GPE, the steaming process was able to significantly improve the interfacial compatibility of the composites and therefore improve the mechanical properties, water resistance, thermal stability, and dynamic rheological properties of the composites.

Wood and bark oil extractives components (OECs) of Pinus sylvestris, Abies alba, Picea abies, and Larix decidua grown in the Czech Republic were analyzed using gas chromatography/ mass spectrometry (GC/MS). The analysis showed the presence of monoterpene, sesquiterpene, diterpenoids, and resin acids. The highest percentages of OECs in the wood of P. sylvestris were α-fenchyl alcohol (26.04%), D-fenchyl alcohol (12.39%), and L-borneol (8.81%); the OECs in the bark included α-methyl-γ-butyrolactone (31.88%) and isodecyl octyl phthalate (15.85%). The most frequently occurring OEC in A. alba wood were 4-hydroxy-4-methyl-2-pentanone (73.36%), α-cedrol (10.08%), and 2,6-dimethyl-1,3,6-heptatriene (7.35%); the most OECs in the bark were di(2-ethylhexyl)phthalate (59.83%), methyl cyclopentane (16.63%), and 13-epimanool (6.31%). P. abies wood OECs included 4-hydroxy-4-methyl-2-pentanone (29.42%), α-cedrol (26.98%), ∆3-carene (6.08%), and terpinen-4-ol (5.42%); the most OECs in the bark were di(2-ethylhexyl)phthalate (30.91%), cyclohexane (12.89%), caryophyllene oxide (8.90%), and α-pinene (4.59%). OECs of L. decidua wood were α-terpineol (26.06%), isoborneol (14.12%), camphene (11.78%), D-fenchyl alcohol (10.39%), and larixol (4.85%); OECs in the bark were larixol (33.29%), phthalic acid mono-2-ethylhexyl ester (16.96%), 13-epimanool (15.40%), and cyclohexane (8.44%).

Methylated fatty acid (FA) compounds in the heartwood and bark of some softwood species, specifically Pinus sylvestris, Abies alba, Picea abies, and Larix decidua, grown in the Czech Republic were evaluated. Strong H2SO4 was used for methylation of the lipids. The highest content of lipid was found in P. abies bark (40.132 mg/g o.d. sample), and the lowest content was in A. alba wood (11.027 mg/g o.d. sample). The highest concentration of FAs was observed in L. decidua bark. The highest percentages of FAs in wood of P. sylvestris were arachidic acid and oleic acid. In bark, the highest percentages of FAs were stearic acid, palmitic acid, and oleic acid. The FAs with the highest concentrations in A. alba wood were arachidic acid, palmitic acid, pentadecanoic acid, and margarinic, and those in bark were behenic acid, lignoceric acid, and arachidic acid. P. abies wood FAs showed arachidic acid, palmitic acid, and margarinic acid, and the bark contained lignoceric acid and arachidic acid. The FAs of L. decidua wood were arachidic acid, palmitic acid, and stearic acid, and in bark they were pentacosylic acid, docosahexaenoic acid (DHA), lignoceric acid, arachidic acid, and behenic acid. The lack of typically dominant unsaturated fatty acids (e.g. 18:1, 18:2), compared to literature values were attributed to the application of strong acid for the hydrolysis.

Contact angle methods are widely used to evaluate the wettability of cellulose-based surfaces and to judge their suitability for different applications. Wettability affects ink receptivity, coating, absorbency, adhesion, and frictional properties. There has been a continuing quest on the part of researchers to quantify the thermodynamic work of adhesion between cellulosic surfaces and various probe liquids and to account for such components of force as the London/van der Waals dispersion force, hydrogen bonding, and acid and base interactions. However, due in part to the rough, porous, and water-swellable nature of cellulosic materials, poor fits between various theories and contact angle data have been observed. Such problems are compounded by inherent weaknesses and challenges of the theoretical approaches that have been employed up to this point. It appears that insufficient consideration has been given to the challenging nature of cellulosic materials from the perspective of attempting to gain accurate information about different contributions to surface free energy. Strong hysteresis effects, with large differences between advancing and receding contact angles, have been overlooked by many researchers in attempting to quantify the work of adhesion. Experimental and conceptual approaches are suggested as potential ways to achieve more reliable and useful results in future wettability studies of cellulosic surfaces.

The weathering performance of wood coated with a combination of rutile TiO2 hierarchical nanostructures and a sol-gel deposit of alkoxysilanes was determined by exposing three sets of specimens to UV light and water spray. The first set consisted of specimens coated with a mixture of methyltrimethoxysilane (MTMOS) and hexadecyltrimethoxysilane (HDTMOS). The second set consisted of specimens coated with nanostructural TiO2 followed by a mixture of MTMOS and HDTMOS. The third set consisted of uncoated control specimens. The wood coated with TiO2 followed by a mixture of MTDMOS and HDTMOS exhibited significantly less surface color change and weight loss as a result of UV light-induced degradation and erosion from water spray in comparison with the other groups. However, the coated surfaces were gradually transformed from hydrophobic to hydrophilic. Despite this apparent weakness, the MTMOS/HDTMOS/TiO2 coating, with superior photostabilization properties and resistance to surface erosion, may be useful for improving the weathering performance of wood coated with semi-transparent wood stains.

The surface roughness of Chinese fir and Eucalyptus wood samples were measured using the stylus profile method in order to investigate the correlation between near infrared (NIR) spectroscopy and surface roughness. The results showed that the NIR spectra absorption showed differences among samples from different surface roughnesses, and the absorption decreased with the increase of the surface roughness. A strong relationship was found between the surface roughness parameters, i.e., the arithmetical mean deviation of the profile (Ra), the ten-point height of irregularities (Rz), and the maximum height of profile (Ry). Based on the NIR spectra of the Chinese fir wood samples and the mixed wood samples of the two wood species, and the correlation coefficients of these two types of wood samples in a calibration set were 0.77 to 0.83 and 0.67 to 0.74, respectively. A relatively poor correlation was found in the model based on the Eucalyptus samples; however, it was still significant. These results suggested that there was relative information about the surface roughness from the NIR spectra, which further illustrated that the surface roughness may influence the effect of models for wood properties built by NIR data.