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In recent years, researchers have pushed to develop an eco-friendly sound-absorbing material derived from natural products capable of reducing noise in indoor sound environments. Wood may fill this niche. In the cross sections of diffuse-porous wood, vessels are widely distributed, a circumstance that provides advantages from a sound absorption perspective. Based on preexisting data concerning the physical properties of various woods, two hardwoods, Homalium (Homalium foetidum) and Jelutong (Dyera costulata), were selected and their sound absorption capability was examined. Gas permeability, pore sizes, and pore types were investigated, and their sound absorption coefficient was calculated. It was shown that Homalium and Jelutong are more gas permeable compared to other hardwoods, especially Jelutong as its pores were larger and its through-pore porosity was greater than that of Homalium. These properties, in fact, are responsible for its superior gas permeability and sound absorption compared to Homalium. It was also determined that an air back cavity was more effective in improving sound absorption in the samples of both woods than increasing the thickness of the samples. Ultimately, this study concludes that Homalium and Jelutong cross sections are well suited for use as sound-absorbing functional building materials.

In this study, the sound absorption coefficient of three low density hardwoods – binuang, balsa and paulownia – were investigated. Their gas permeability and pore size were measured, and their pore shapes were classified into through pore, blind pored, and closed pore, as specified by the International Union of Pure and Applied Chemistry (IUPAC). Among the three species, obvious that paulownia had lowest sound absorption when the two of others showed higher sound absorption. Although paulownia is a high porosity wood, most of its vessels are blocked by tyloses; it is therefore difficult for sound waves to enter its pores, which results in poor sound absorption performance. This study showed that the higher the through pore porosity, the higher was the gas permeability, which led to improvement of the sound absorption performance. It was also found that the sound absorption coefficient of the three species woods increased at low frequencies as the size of an air cavity between the specimens and tube’s wall increased.

Small-diameter logs are intended to function as high-value structural timber. Bending strength properties is an essential phenomenon for structural lumber. Herein, the modulus of elasticity, the mo...

Steam explosion is a useful method to soften and dimensionally stabilizing wood. A significant increase in air permeability and sound absorption capability of steam-exploded palmwood compared to untreated palmwood is observed due to changes in cell wall. Cell wall’s changes are characterized by instrumental techniques such as Fourier transform infrared spectroscopy, X-ray diffraction, field emission scanning electron microscope and gas permeability by capillary flow porometry and sound absorption coefficient by two-microphone transfer function method. The average increase in air permeability (259.3%) and sound absorption coefficient (52.33% at frequency range of 250–6400 Hz) of steam-exploded samples is higher than that of untreated samples. Color of steam-exploded woods become black due to chemical reactions in cell wall during steam explosion. The color change, air permeability and sound absorption coefficient of wood are correlated with the findings. These results suggest that low-pressure steam explosion could be considered as an effective technique for improving the air permeability and sound absorption capability of palmwood in the longitudinal direction. This approach could be useful to manufacture sound absorption board to control the acoustical housing environment.

We investigated the effect of ultrasonic treatment on Malas (Homalium foetidum) gas permeability and sound absorption coefficient using the transfer function method. Results showed a longitudinal average Darcy permeability constant of 2.02 (standard deviation SD 0.72) for untreated wood and 6.15 (SD 3.07) for ultrasound-treated wood, a permeability increase of 3.04 times. We also determined the average sound absorption coefficients in the range of 50 to 6.4 kHz and NRC (noise reduction coefficient: average value of sound absorption coefficient value at 250, 500, 1000, and 2000 Hz) of untreated Malas. Those values were 0.23 (SD 0.02) and 0.13 (SD 0.01), respectively, while those of ultrasonic-treated Malas were 0.28 (SD 0.02) and 0.14 (SD 0.02), a 19.74% increase in average sound absorption coefficient.

The demand for noise control in residential environments is steadily increasing, but the currently available noise-reducing materials used in walls and floors are unsustainable and expensive. As an alternative, wood-fiber could be a good resource to manufacture eco-friendly acoustic materials. In this study, fiberboards were prepared by mixing wood-fibers (Pinus densiflora) with melamine-urea-formaldehyde resin adhesive, obtaining specimens with different final densities and resin contents. The acoustic, physical, and morphological properties of the fiberboards were investigated. The sound absorption was greatly influenced by the density of the fiberboard: lower densities showed higher sound absorption performances. Furthermore, the low-frequency absorption coefficient was higher for lower resin contents. The materials met all the criteria required by the Korean standards for fiberboards. As the density increased, the dimensional stability and the bending strength increased; in contrast, the physical properties were not affected by the resin content. Microscopy observations confirmed that specimens with different densities and resin contents had different porosities; the porosity was assumed to be the main property that governs the noise-reducing ability. Due to their eco-friendliness and inexpensiveness, these fiberboards offer themselves as efficient and effective alternative sound-absorbing materials.

The larch boxed-heart timbers with a cross section of 100 × 100 mm were dried after steamed at 100 °C dry-bulb temperature and 0 °C wet-bulb depression for 5 h, and then dried at 120 °C dry-bulb temperature and 30 °C wet-bulb depression for 8, 12 and 16 h, respectively, in order to determine optimal treatment time for the timber. This study indicated that the pretreatment of 12 and 16 h prevented both the surface and internal check of the timber. However, the pretreatment delayed drying time by at least 19%.

Graphene is a material that is very cheap but delivers high results in almost every area of human life. The multifunctional properties have made it a subject of great interest among researchers. An advanced research milestone in graphene production is the ability to produce composite materials. The surface morphology and particle size of the metal nanoparticles are highly significant in their catalytic properties and limited in their use in catalysis. Therefore, the progress of multifunctional materials for catalytic application is urgently required. In recent years, polymer-graphene composites with their enhanced catalytic, mechanical, electrical, and physical properties have emerged as one of the really popular multifunctional materials. This chapter deals with graphene-based polymer composites functioning with catalytic properties. The chapter describes in detail the recent promising research into polymer-graphene composites for catalytic applications such as photocatalytic activity, electrocatalytic activity, catalytic activity in hydrogenation reaction, and catalytic activity in the lithium-air battery. This chapter also outlines the future scope of the catalytic study.

Recently, high-power density electronic components and devices used in various fields have been highly integrated for miniaturization and weight reduction. Therefore the heat generation and low thermal expansion have become a serious issue for electronic devices that strongly affect their working life, performance, and reliability. In recent years, most researchers have investigated the improvement of the thermal conductivity of polymer matrix containing conductive fillers. Graphene, as a conductive filler, has unique tuned properties such as mechanical properties, thermal stability, electrical and thermal conductivity. Graphene-based polymer composites are expected to have exceptional electrical conductivity and thermal transport properties, making them promising in various practical applications. In this chapter, we will describe the thermal conductivities of graphene-based polymer composites and provide guidance on the fabrication of high thermal conductivity polymer composites.

This study investigates the effects of heat treatment time and presence of an air back cavity on the sound absorption performance of Indonesian momala (Homalium foetidum (Roxb.) Benth.) and Korean red toon (Toona sinensis (A. Juss.) M. Roem.) cross sections. To examine the porous characteristics of the two species before and after heat treatment, gas permeability, pore size, and porosity analyses were conducted. Additionally, the sound absorption coefficient was measured based on various heat treatment times and air back cavity sizes. The results showed that, with heat treatment at 210 °C for 6 h, the gas permeability improved by 4.3% for the momala and 38.5% for the red toon, the maximum pore size was improved by 5.25% in the momala and 26.0% in the red toon, and the through-pore porosity improved by 22.7% for the momala and 117.0% for the red toon. Due to these pore structure changes, the noise reduction coefficient (NRC) of the heat-treated momala improved by 6.8%. When a 3-cm air back cavity was applied to the heat-treated momala, the NRC was improved to 92.5%. Similarly, when the same air back cavity was applied to the heat-treated red toon, the NRC was improved to 190.7%. This study demonstrated that an increase in pore size and through-pore porosity by heat treatment triggered an increase in the sound absorption coefficient. Additionally, when an air cavity was applied, the sound absorption coefficient of both heat-treated wood species was increased at low frequency. From the results of this study, we expected that heat-treated momala and red toon cross-sections can be utilized as eco-friendly ceiling materials with sound absorption function.

This research aimed to study the efficacy of oxidation in wood cell walls by ammonium persulfate solution and the performances in sound absorption coefficients and gas permeability for cross sectional Oak wood (Quercus mongolica) species. Reaction parameters were optimized and extensive instrumental characterization techniques were used to study cell wall modifications, such as X-ray photoelectron spectroscopy, X-ray diffraction, attenuated total reflectance Fourier transforms infrared spectroscopy, and scanning electron microscope. The oxidation treatment changed the chemical compositions of wood (hemicellulose, cellulose, and lignin), boosting wood porosity (12%) and gas permeability (39%). The effectiveness accelerates improvement of average sound absorption coefficient at each frequency range: 250–500 Hz (4.6%), 500–1000 Hz (26.8%), 1000–2000 Hz (31.8%), 2000–6400 Hz (57.8%) and overall 250–6400 Hz (47.1%) compared to the control samples. Simple wood oxidation treatment could be helpful for novel research and wood based sound absorption materials to manage the acoustic housing environment.

An investigation of sound absorption in 6 species of hardwoods according to the pore structure of cross-sections revealed that higher gas permeability was associated with greater sound absorption at high frequencies. In addition, diffuse-porous wood exhibited superior sound absorption performance compared with ring-porous wood. Through-pore porosity was associated with improved sound absorption in the cross-sections of all 6 species, while closed-pore porosity was associated with poor sound absorption. The results of these studies could lead to development of hardwood products with superior sound absorption and help elucidate the roles of porosity in drying, impregnation, and thermal insulation properties of wood.

The continuing development of industrialization and increasing population density has led to the emergence of noise as an increasingly common problem, requiring various types of sound absorption and insulation methods to address it. Meanwhile, the recycling of resources to ensure a sustainable future for the planet and mankind is also required. Therefore, this study investigates the potential of corrugated cardboard as a resource for noise reduction. The sound absorption and insulation performance of non-perforated corrugated cardboard (NPCC) were measured, and modified corrugated boards were fabricated by drilling holes either through the surface of the corrugated board alone or through the corrugated board in its entirety. The sound absorption/insulation performance both of perforated corrugated cardboard (PCC), and perforated corrugated cardboard with multi frequency resonators (PCCM) were measured using the transfer function method and the transmission matrix method. To determine the effectiveness of NPCC, PCC, and PCCM in noise reduction, the sound pressure level was analyzed by applying it to a home blender. The results showed PCCM’s sound absorption and insulation performance to be excellent. On the basis of these findings, we propose the use of PMMC as an eco-friendly noise reduction material.

A sustainable supply of pure water is a great challenge in most developing and third-world countries. Nanomaterial-based technology offers technological development for wastewater purification. Nanocatalysis hydrogenation of nitroarene and dye molecules is a hot model in many research fields. Herein, we report eco-friendly and facile technology to synthesize Ag-Au bimetallic nanocomposites. The synthesized nanocomposites are characterized by ultraviolet–visible spectroscopy, Fourier-transform infrared spectroscopy, X-ray diffraction, field emission scanning electron microscopy and high-resolution transmission electron microscopy. The synthesized nanocomposite can efficiently degrade Congo red and 4-nitrophenol in water and in the presence of sodium borohydride. The results show that it degrades Congo red and 4-nitrophenol entirely within 6 and 7 min, respectively. These results could be useful for the green synthesis of Ag-Au bimetallic nanocomposites and help to remove organic dye molecules and nitroaromatics from wastewater.

More interest in larch (Larix kaempferi) has been taken because of a greater focus on environmental properties. Steam explosion is an inexpensive and facile approach for the increasing rate of drying and durability of wood. A significant improvement in gas permeability and sound absorption coefficient of steam-exploded larch wood relative to the control wood is observed. It is due to structural changes in the cell wall that is proved by Fourier transform infrared spectroscopy, field emission scanning electron microscope, X-ray diffraction, and Energy-dispersive X-ray spectroscopy. The average increase in SAC of steam-exploded samples is 33.33% higher than the control samples at a wide range of frequency 250-6400 Hz due to the increasing air permeability (190.1%). Color of treated larch wood changed to black due to several chemical reactions in the cell wall and reduced of –OH functionality during the steam explosion. These findings summarized that steam explosion affects softwood cellulose cell walls, and the cross-section surface of larch wood could be considered for improving acoustic comfort in the building.

The square timbers of larch having cross section of 90 mm × 90 mm were glued laterally to be formed 1,200 mm × 2,400 mm panels which were used as cores for CLT wall panels. Then, structural plywood panels having size of 1,200 mm × 2,400 mm were used as cross band covering the small square timber cores to manufacture CLT wall panels. The sound absorption rate of CLT wall panels and polyester board attached CLT wall panels were investigated. The mean sound absorption coefficients of the former and the latter in the frequency range of 100-6400 Hz were 0.21 and 0.74, respectively. The noise reduction coefficients (NRC) of those were 0.21 and 0.40, respectively. Also, the mean sound transmission loss of CLT wood panel in the frequency range of 50-1600 Hz was 45.12 dB and that value at the frequency of 500 Hz was 42.49 dB. It was suggested that the polyester board attached CLT wall panels could be used as housing wall because of its high sound absorption rate and high sound transmission loss.

Designing a suitable noble metal-free electrocatalyst for the hydrogen evolution reaction (HER) is enduring challenge. Molybdenum disulfide (MoS2) shows structural and electronic advantages as potential HER electrocatalyst. The structural and electronic design of MoS2 electrocatalysts should be considered to improve the efficiency and stability of MoS2 based electrodes. This report shows that the presence of synergistic interaction significantly improves the HER electrocatalytic activity of defect-rich 3D rGO-CNT/MoS2 composites. The Defect-rich conductive scaffold supported nanostructures can improve the catalytic performance and stability. Lowering of the HOMO-LUMO gap supervises the charge transfer resistance of the nanostructure. The turnover frequency value indicates that 3D rGO-CNT/MoS2 acts as the potential electrocatalyst and the overpotential observed at a current density of 10 mA cm−2 in acidic and alkaline media are 88 mV and 172 mV, respectively. This investigation provides a new idea to develop molybdenum disulfide and scaffolds based 3D nanostructures to improve the inherent electrocatalytic activity of HER.

Among the various methods used to improve the sound absorption capability of wood, we focused on delignification in Indonesian momala (Homalium foetidum) and Korean red toon (Toona sinensis). We performed gas permeability, pore size, and porosity analyses and evaluated how the change in the pore structure affects the sound absorption capabilities. Results show that delignification increased the through-pore porosity and improved sound absorption capability in both species. In addition, the air gap in the rear space maximized the sound absorption of momala and the red toon. The noise reduction coefficient (NRC) of delignified momala (90 min) with a 3 cm air gap was 0.359 ± 0.023. This is approximately 154.6% higher than that of untreated momala without an air gap. The NRC of delignificated red toon (90 min) with a 3 cm air gap was 0.324 ± 0.040, an increase of 604.3% over untreated red toon without an air gap.

Steam explosion is a useful method to soften and dimensionally stabilizing wood. The effects of steam explosion at low pressure (6 bar) on wood cell walls are characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), capillary flow porometry and two-microphone transfer function. The average sound absorption coefficient (SAC) of treated Chinaberry samples on the cross-sectional surface exhibited significant improvement of 79% relative to control specimens over a wide frequency range of 250–6400 Hz. Whereas, a little increment SAC of 5% was observed in the case of Ginkgo wood. Color of steam-exploded woods became black due to chemical reactions in wood cell walls during the steam explosion. The air permeability, SAC and color change are correlated with the results of FTIR and XRD. These results suggest that steam explosion could be used to manufacture wood-based sound absorption board to control the acoustical housing environment.

This study was conducted to determine the relation between the dynamic modulus of elasticity and the static modulus of elasticity, and the relation between the dynamic modulus of elasticity and the modulus of rupture of mandarin peel–sawdust composite boards. The result of this study was as follows: There was highly close linear correlation between the dynamic modulus of elasticity and the static modulus of elasticity, modulus of rupture of the mandarin peel–sawdust composite boards with the density of 0.4, 0.5 and 0.6 g/cm3, and the mandarin peel content of 10, 20, 30 and 40%, thus, the static modulus of elasticity and the modulus of rupture can be predicted from the dynamic modulus of elasticity measured by free vibration test using resonance frequency.

This study was conducted to develop a new drying technology in order to quickly and massively dry bamboo tubes without crack and check. The bamboo tubes with the diameter of 45 mm - 68 mm had been impregnated in the solution of PEG-1000, and then were dried under room temperature and high temperature, respectively. The cracks occurred on all control specimens while no cracks were found on PEG treated specimens during drying at room temperature due to effect of PEG restraining the circumferential shrinkage of bamboo tube. But the drying period of this method was too long (200 days) compared to 10 hours of kiln drying. During fast high temperature drying, cracks occurred on all control specimens, but no cracks were found on PEG treated specimens, which could be accounted for more solidified PEG due to higher drying temperature and faster drying rate, and the tension set formed on the surface of bamboo tube in the early stage of drying owning to high drying temperature and low relative humidity. Thus, it is advised that PEG treated bamboo tube should be fast dried at high temperature in order to not only prevent crack or check in short drying period but also increase the dimensional stability of the products made of bamboo tubes.

In this study, changes in gas permeability and pore structure of wood are evaluated after heat treatment with temperatures ranging from 190 to 230 °C for 6 h for both hardwood (yellow poplar: Liriodendron tulipifera) and softwood (Korean red pine: Pinus densiflora). The purpose of this study is to investigate changes in pore size, content of three pore types (through pore, blind pore, and closed pore), as defined by IUPAC, and gas permeability by increasing heat treatment temperatures in hardwood and softwood using capillary flow porometry and gas pycnometry. As the heat treatment temperature increased, only through pore porosity increased, causing an increase in gas permeability.

Wetting is a key problem in wood finishing because water causes deterioration and reduces the durability of wood. Herein, hydrophilic wood has been modified into a hydrophobic wood through simple surface coating using polyvinyl acetate (PVAc) / reduced graphene oxide (rGO)-poly (diallyl dimethylammonium chloride) (PDDA). The synthesized graphene oxide (GO) from graphene flakes is used for chemical modification with urotropin in presence of sodium borohydride. The hydrophobic property of PVAc has been increased by modified graphene oxide dispersed at the presence of PDDA in methanol. The synthesized polymer composite is used coating on the various wood surfaces (radial and cross-sectional). Synthesized materials are characterized by extensive characterization techniques. The water contact angle of wood surface coated with PVAc/rGO-PDDA shows 187.8 % better than uncoated wood and 20.7 % better than PVAc coated wood and 2.4 % better than commercial wood stain coated wood. This facile, low cost and eco-friendly approach could be used in a variety of applications.

Hygrothermal treatment is an important and eco-friendly process for softening and improving the quality of wood. Paulownia (Paulownia coreana) hardwood species mostly used to design household furniture, musical instruments, plywood and particleboard. The effect of hygrothermal on the wood cell walls has studied extensively in recent years. However, the relationship between sound absorption coefficient (SAC) and alteration of the cellulose/hemicellulose cell walls of hardwood species are scarcely found. Here, hygrothermal effect with varying temperature (90–120 °C about 2 h) are studied, confirmed by extensive characterization techniques, and results of SAC are reported. Hygrothermal treated paulownia at 110 °C exhibits improved SAC ~ 81.8% (from 0.1115 to 0.2028) at 2000 Hz compared to the untreated paulownia. The enhancement of SAC in an average is 47.42% in a wide range of frequency (2000 Hz–6400 Hz) has been observed. The hygrothermal treated paulownia hardwood can be useful to manufacture sound-absorption board for healthy housing environment.

Wood is one of the most usable natural composite. Noise pollution from the various sources affect the human health and environment worldwide. How to reduce noise pollution has become a major issue? Hence, finding the proper sound absorbing wood is necessary for improved acoustic environment. In the present work, we choose most useful ten different hardwood species. Analysis of basic properties, surface morphology by HR-FESEM, elemental analysis using EDAX, cellulose crystallites by XRD, air permeability by a capillary flow porometer, sound absorption coefficient and sound transmission loss by microphones transfer function method using impedance tube is discussed in detail. The Hackberry wood shows better sound absorption coefficient (0.640 at 4000 Hz), sound transmission loss (15.23 at 4000 Hz) due to the higher value of Darcy permeability constant (9.78), porous surface morphology and lower cellulose crystallites (16.6%). These results became extremely important to the engineers for designing good acoustic housing environment.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

The drying defects of refractory species are known to begin occurring in the early stages of kiln drying. Therefore, monitoring the strain distribution in wood at these early stages of drying is expected to be helpful for the reduction of possible defect development. In this study, the strain distribution of red oak specimens was progressively monitored on the tangential surface of the wood using an optical measurement system based on the digital image correlation (DIC) principle. The specimens were kiln-dried with three different initial conditions. The strain distribution maps obtained at various moisture contents clearly illustrated the progress of the strain development in the wood. In addition, strain velocities and strain ratios were calculated from the data extracted from the strain distribution maps. These parameters could be used for developing or modifying a kiln-drying schedule of a refractory species.

본 연구는 밀도와 귤박첨가율이 다른 톱밥-귤박 파티클보드의 동적·정적탄성계수와 휨강도를 측정, 비교하여 밀도와 귤박의 첨가율이 파티클보드의 역학적 성능에 주는 영향과 동적탄성계수와 정적 휨강도 성능사이의 관계를 조사하였다. 톱밥-귤박 파티클보드의 밀도가 0.4에서 0.6 g/cm3로 증가할수록 휨성능은 증가하여, 밀도가 휨성능에 크게 영향하였으며, 밀도 0.4 g/cm3와 0.5 g/cm3의 톱밥-귤박 파티클보드에서 귤박의 첨가량이 증가할수록 휨성능은 감소하는 경향을 나타내었다. 톱밥-귤박 파티클보드의 동적탄성계수, 정적탄성계수 그리고 휨강도 사이에 높은 상관관계가 확인되었으며 양단 자유 휨진동시험에 의한 동적탄성계수로부터 비파괴적으로 정적 휨강도 성능의 예측이 가능할 것으로 사료되었다.

The effect of polyethylene glycol (PEG) treatment was investigated relative to surface checks of red and Korean pine round wood for building Korean-style homes. The logs used for this study were impregnated with a solution of PEG-1000 for three weeks, and then they were dried to a moisture content of about 15% at the temperature of 120 °C within the drying time of 49 h. During the middle stage of drying, slight surface checks were found on red pine PEG-treated logs compared with severe surface checks on red pine control logs. Due to PEG treatment and high drying temperature, at the end of drying, apparent surface check was not found on red pine PEG-treated logs compared with serious surface checks on the corresponding control log. No surface checks were discovered on Korean pine logs during and after drying due to the PEG effect. Thus, PEG treatment was effective in preventing surface checks on red and Korean pine logs during drying at high temperature.

To achieve a deeper and more uniform impregnation of water-soluble phosphorous-based fire retardants (WPFRs), in this work several physical pretreatment methods were developed including kerfing, boring, and the combination of both for structural square-wood posts in wooden buildings. Research was performed on three wood species, sugi (Cryptomeria japonica), larch (Larix olgensis), and Douglas fir (Pseudotsuga menziesii Franco), which are generally recognized as refractory wood species. The effects of pretreatment method on chemical uptake, chemical penetration, and mechanical properties were evaluated. The methods were compared with the incising method, a traditional method used for wood preservation. The results indicated that the pretreatments effectively increased the chemical uptake and penetration, especially in larch wood. Although the traditional incising method also increased the chemical uptake, it decreased the modulus of rupture (MOR) and compressive strength. The boring and combined method with a boring diameter less than 12 mm are recommended for WPFR wood impregnation.

To clarify the mechanical behaviour differences between earlywood and latewood, separated the early- wood and the latewood specimens loaded to the rupture with tensile load parallel to the grain. The separated test specimens for tensile test were prepared from douglas fir (Pseudotsuga menziesii) and stress-strain relation was evaluated by optical measurement system using the Digital Image Correlation (DIC), which can visualize strain during the tensile test. The results are summarized as follows: The estimated strain data by universal testing machine show good accordance with that estimated by DIC. There was a difference in the fracture pattern of the earlywood and the latewood of douglas fir that the surface of ruptured earlywood typically simple while that of was somewhat complicate. The longitudinal tensile strength of earlywood specimens of douglas fir at wood height from ground 12.8 m, 9.8 m, 6.7 m and 0.9 m were 51 MPa, 69 MPa, 110 MPa and 114 MPa, while those of latewood were 208 MPa, 234 MPa, 247 MPa and 198 MPa. Elastic modulus in the longitudinal tensile of earlywood speci- mens of douglas fir at wood height from ground 12.8 m, 9.8 m, 6.7 m and 0.9 m were 5458 MPa, 7202 MPa, 9705 MPa and 8761 MPa, while those of latewood were 13747 MPa, 19405 MPa, 17365 MPa and 14044 MPa.

Changes in the physical and mechanical properties and anatomical structures of spruce (Picea) and larch (Larix) specimens before and after fire-retardant impregnation were studied. Results indicated that the static modulus of elasticity (MOE), dynamic modulus of elasticity (DMOE), and the Brinell hardness of the specimens decreased for both wood species upon post-treatment. This could be accounted for by the degradation of hemicelluloses by the phosphorus-based compound, the minute cracks in the latewood cell wall, and the enlarged width of the cell lumen of the specimen resulting from the vacuum-pressure treatment. However, the decreased ratio of the MOR and DMOE to density contributed to lower sound transmission, which is expected to be important in a housing environment.