In this book chapter, we first provided a concise overview of global forest products and their impacts and benefits. Then, we introduced the theory of green, sustainable, and circular forest products to our readers. Through a literature review and theoretical framework, we have presented several case studies regarding the development of green, sustainable, and circular forest products globally, focusing on raw materials, process control, and panel qualities. Based on the definition of the theory, we have analyzed and highlighted are as within the forest products sector, including production, market, research, and education that require enhancement and improvement. Finally, we have shared our perspective on the future development of the forest products industry.

The combined influence of specimen size and strain rate on the mechanical behaviour of small-diameter bamboo culms remains insufficiently characterised. This study investigates the longitudinal compressive strength of Chimonobambusa utilis through axial compression tests on specimens measuring 15 × 15 × 5 mm, 18 × 18 × 6 mm, and 21 × 21 × 7 mm under strain rates of 10−4, 10−3, and 10−2 s−1. Coupling experimental data with theoretical analysis, this study develops a size–strain rate interaction model to quantitatively assess the effects of specimen size and strain rate on the compressive strength of small-diameter bamboo. Increasing specimen size reduced strength and shifted failure modes from shear to buckling and splitting. At a strain rate of 10−4 s−1, strength decreased from 73.35 MPa for the 15 × 15 × 5 mm specimens to 62.84 MPa for the 21 × 21 × 7 mm specimens. Conversely, increasing the strain rate from 10−4 s−1 to 10−2 s−1 for the 15 × 15 × 5 mm specimens increased strength from 73.35 MPa to 80.27 MPa, indicating suppressed crack propagation. The Type II Weibull model exhibited higher predictive accuracy and parameter stability than the Type I variant. Coupling the Type II Weibull function with a power-law strain rate term and an interaction exponent developed a predictive equation, achieving relative errors below 5%. The findings demonstrate that specimen size predominantly governs strength, whereas strain rate exerts a secondary but enhancing influence. The proposed coupling model enables reliable axial load prediction for small-diameter bamboo culms, supporting material selection and dimensional optimisation in structural applications.

Yunnan Dendrocalamus sinicus Chia et J. L. Sun (YDS) is a giant bamboo species with a diameter at breast height of up to nearly 40 cm. It is endemic to Yunnan, China, and only a very small portion of it is directly used as load-bearing beams and columns in the dwellings of ethnic minorities, such as in Dai architecture. Due to the structural characteristics of its hollow and thin walls, systematic physical and mechanical property testing of this species faces significant challenges in terms of methods and means. This issue has become one of the main barriers to the realization of its large-scale industrial use. Therefore, this paper systematically tests and studies YDS’s three kinds of strength (tension, compression, and shear), modulus of elasticity, and six Poisson’s ratios with the help of digital image correlation (DIC) technology and self-created material testing methods. The (1) tensile, compressive, and shear strengths and moduli in longitudinal, radial, and chordal directions; (2) tensile strengths and moduli of bamboo green, flesh, and yellow layers in the thickness direction of the bamboo wall; and (3) six Poisson’s ratios under tensile and compressive stresses were obtained for YDS. It was also found that the tensile strength (378.8 MPa) of the green layer of YDS exceeded the yield strength (355 MPa) of 45# steel, making it a potential high-strength engineering material or fiber-reinforced material.

To mitigate the potential risks posed to human health and the environment by formaldehyde emissions originating from formaldehyde-based adhesives, adopting low-toxicity and biodegradable glyoxal as an alternative to formaldehyde in the synthesis of amino resin adhesives represents a direct, convenient, and promising strategy. Urea-glyoxal (UG) resins represent the most minimalist category within the family of glyoxal-based wood adhesives. However, their widespread application is limited due to inferior adhesive properties and inadequate water resistance. In this study, we enhanced the bonding properties of urea-formaldehyde (UG) by formulating EPn-UG wood adhesive, which integrates UG resin with epoxy resin (EP). Structural characterization revealed successful incorporation of the epoxy backbone into the low molecular chain of the UG resin via ring-opening reactions between the epoxy groups and amino groups on the UG resin. Additionally, the EPn-UG adhesive exhibits a lower curing temperature and higher storage modulus. At an EP addition level of 5%, the dry and wet strength of EP5-UG bonded plywood, measured after immersion in water at room temperature for 24hours, were recorded as 1.65 and 1.02MPa, respectively. This demonstrates a significant improvement of 34% and 149% compared to UG resin. Notably, the bonding strength exhibited a remarkable breakthrough from 0 to 0.61MPa after immersion in water at 63°C for 3hours. These findings suggest that the introduction of EP enhances the formation of a denser crosslinked network, effectively boosting both the bonding strength and water resistance of UG adhesives. This study presents a novel approach for investigating formaldehyde-free adhesives, further facilitating the industrial implementation of UG resin.

The present study provides a comprehensive discussion on the structure and properties of a novel high-strength rapeseed protein-based adhesive, which effectively mitigates the emission of free formaldehyde in conventional wood-based panels used as adhesives. The rapeseed protein (R) extracted from rapeseed cake was integrated with glyoxalde-urea (UG) resin to prepare rapeseed protein-based adhesive (RUG). The structure of RUG was characterized by FTIR, & Oslash;S, 13 C NMR, etc. The results indicate that RUG with good performance can be obtained by reacting at 80 degrees C for 1 h with G/U molar ratio of 2.0 and a system pH of 5 -6. When preparing plywood, a small quantity of diphenylmethane diisocyanate (MDI) is introduced into the system as a crosslinking agent to further enhance the strength of the plywood. The results showed that when the amount of MDI is 3 % of the total mass of the RUG adhesive, the bonding strength of the RUG adhesive has been greatly improved, and the performance of the prepared plywoods meets the requirements of GB/T 9846-2015 for Class II plywood. The study provides a comprehensive discussion on the structure and properties of a novel high-strength rapeseed protein-based adhesive, which provided a reference for replacing formaldehyde-based adhesives.

The formaldehyde -based adhesive is commonly used in wood industry; however, the emission of formaldehyde is a fatal defect, which endangers people's health as well as pollutes the environment. Herein, the non-toxic and low -volatility glyoxal (G) is chosen to react with dimethylolurea (DMU) to prepare a novel and excellent waterresistant wood adhesive of glyoxal-dimethylolurea (G-DMU) resin. Quantum chemical calculations, structure characterizations, and performance measurements are carried out to study the reaction mechanism, and structure -performance relations of G-DMU resin with different DMU/G molar ratios. The results show that during the synthesis of G-DMU resin, the hydroxyl compounds N-p-G-DMU and N-p-G1-DMU, as well as the carbocation intermediates C-p-G-DMU and C-p-G1-DMU are formed by the addition reactions between DMU and protonated glyoxal (p -G and p -G1). The plywood bonded with G-DMU resin with the optimum DMU/G molar ratio of 1.2:1.0 has the best water resistance. Its wet shear strength is increased by 145% (cold water) and 193% (63 degree celsius) over the DMU/G molar ratio of 0.8: 1.0. The analyses of structure characterizations reveal that the generation of C=N, C-O-C, N-C-N, and heterocyclic rings, simultaneously, the main cross -linked components concentratedly are characterized in 400-500 Da, 500-550 Da, 698 Da, and 712 Da regions. In addition, the high molecular weight oligomers at 658-712 Da, 874 Da, 1037 Da and 1213 Da promote the formation of a highly cross -linked network during the curing process. Meanwhile, these results are in good agreement with the results of quantum chemical calculations. Thus, this work establishes the theoretical foundation for the novel glyoxal-based resin of G-DMU resin.

The multi-co-condensed resins of melamine−phenol−urea−glyoxal(MPUG) with different molar ratios of raw materials of melamine(M), phenol(P), urea(U) and glyoxal(G) have been successfully prepared under weak acid conditions. The basic property, wettability and bonding property of the MPUG resins were fully examined, and then the synthetic process of the co-condensed resins was optimized. Fourier transform infrared spectroscopy(FTIR), 13C nuclear magnetic resonance spectroscopy(13CNMR) and X-ray photoelectron spectroscopy(XPS) were applied to characterize the resins' structure. The results showed that the addition of M and P improved obviously the bonding performance of UG resin, especially for the water resistance of the plywood. The three-layer poplar plywood bonded with MPUG resin with the molar ratio of raw materials(M∶P∶U∶G) of 0.2∶0.1∶1.0∶1.4 has optimum bonding strength. The dry bonding strength, wet bonding strength in cold water for 24 h and wet bonding strength in 63 ℃ hot water for 3 h are 1.62 MPa, 0.75 MPa and 0.43 MPa, respectively. Moreover, the resin and its plywood are of free-formaldehyde emission and can be directly used for indoor under dry condition.

To study the static bending creep properties of glass fiber reinforced wood, glass fiber reinforced poplar (GFRP) specimens were obtained by pasting glass fiber on the upper and lower surfaces of Poplar (Populus euramevicana, P), the performance of Normal Creep (NC) and Mechanical Sorptive Creep (MSC) of GFRP and their influencing factors were tested and analyzed. The test results and analysis show that: (1) The MOE and MOR of Poplar were increased by 17.06% and 10.00% respectively by the glass fiber surface reinforced composite. (2) The surface reinforced P with glass fiber cloth only exhibits the NC pattern of wood and loses the MSC characteristics of wood, regardless of the constant or alternating changes in relative humidity. (3) The instantaneous elastic deformation, viscoelastic deformation, viscous deformation and total creep deflection of GFRP are positively correlated with the stress level of the external load applied to the specimen. Still, the specimen’s creep recovery rate is negatively correlated with the stress level of the external load applied to the specimen. The static creep deflection and viscous deformation of GFRP increase with the increase of the relative humidity of the environment. (4) The MSC maximum creep deflection of GFRP increased by only 7.41% over the NC maximum creep deflection, but the MSC maximum creep deflection of P increased by 199.25% over the NC maximum creep deflection. (5) The Burgers 4-factor model and the Weibull distribution equation can fit the NC and NC recovery processes of GFRP well.

In order to investigate the mechanism of the effect of asymmetric reinforcement on the static-bending properties of wood, this paper tests and analyzes the static-bending properties of SPF wood and seven different types of asymmetric fiber surface-reinforced wood (AFRWC) formed by SPF wood as the substrate and bamboo and carbon fibers as the reinforcement materials. The results of the study found that (1) the moduli of rupture of the seven types of AFRWC were increased to varying degrees, but the static-bending moduli of elasticity increased or decreased; (2) the asymmetric reinforcement changed the cross-section strain distribution and damage type of the wood in static bending; (3) the results of the cross-section strain-field tests and the ABAQUS finite element simulation showed that the asymmetric reinforcement method of bonding the bamboo material and the two layers of CFRP in the compression and tensile zones, respectively, can greatly enhance the static-bending performance of the wood. The error between the simulated and measured values of specimens MOR and MOE is only −0.7% and −7.3%, respectively. This type of asymmetric reinforcement makes it possible to obtain a more reasonable cross-section stress distribution.

以含有竹青的巨龙竹(Dendrocalamus sinicus)和尾巨桉(E.urophylla×E.grandis)为原料,使用酚醛-异氰酸酯树脂制备正交胶合竹木(Cross laminated bamboo timber,CLBT),分析竹青对竹木间胶合能力、抗弯强度以及尺寸稳定性的影响.结果表明:使用酚醛树脂制备的含竹青CLBT,其抗弯性能弱于去竹青CLBT.当酚醛-异氰酸酯树脂作为胶黏剂时,含竹青CLBT具有较高的抗弯强度和尺寸稳定性.竹青会降低竹木间胶合能力,但会提高CLBT的抗弯性能.研究结果为实现竹青的合理利用提供了依据.

This study investigated the effects of adhesive resination and bamboo strand content on the physical and mechanical properties of thick Bamboo-Wood-oriented strand board (BWOSB), such as the air dry density (ADD), internal bond strength (IB), water absorption thickness swelling (TS), modulus of rupture (MOR), modulus of elasticity (MOE), and gluing properties. The raw materials used included large strands prepared from Chinese fir (Cunninghamia lanceolata), bamboo (Phyllostachys edulis), and modified isocyanate resin (PMDI). In this study, BWOSB specimens with different adhesive resination and bamboo strand content were fabricated, and their physical–mechanical properties were examined. It was found that the physical and mechanical properties of BWOSB with 8% PMDI resination were better than those with 5%, and their gluing damage was mostly in the form of the tearing of the raised vascular bundles of bamboo strands and the wood-breaking damage of wood strands. With the increase in the proportion of bamboo strands, the internal bonding strength and the short-span shear strength of BWOSB showed a tendency to decrease at first and then increase. The swelling rate of the water absorption thickness showed a tendency to decrease, and the other properties of BWOSB did not show a clear correlation with the change in the proportion of bamboo strands. The unique gluing interface between the bamboo and wood strands, which either used the “keyway” type of gluing effect or the “nail” type of gluing effect, determined the gluing performance of BWOSB, and the proportion of bamboo and wood strands influenced the gluing interface and gluing type of BWOSB, which ultimately affected the gluing performance of BWOSBs. The proportion of bamboo and wood strands also affected the gluing properties of BWOSBs by influencing the gluing interface and gluing type. This study provides a reference for the development of the production process of thick BWOSB and its application in the field of heavy load construction.

Furfurylation can effectively improve the quality of fast-growing wood, but its leachability is unclear. In this study, fast-growing poplar (Populus sp.) and Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.) were impregnated with low concentrations of 5%–20% furfuryl alcohol (FA), and the chemical and microscopic changes during leaching tests were analyzed by UV spectra and confocal laser scanning microscopy (CLSM). The results show that FA impregnation can regulate the weight percentage gain, but its effectiveness in regulating the cell wall bulking coefficient decreased as the impregnation concentration was increased. Impregnation with 15% and 20% FA showed no significant difference in the effect on volume swelling efficiency. The inverse relationship between the concentration of FA and the leaching rate was demonstrated by leaching tests, UV spectra, and CLSM. Notably, the leaching rate of poplar and Chinese fir wood was more than 30% when impregnated with 5% FA. Although the entirety of the furfuryl alcohol was deposited in the cell wall when impregnated with low concentrations of FA, the binding was not stable. The weight percentage gain of furfurylated Chinese fir was greater than that of poplar, but its leaching rate was lower, indicating that the cured furfuryl alcohol resin in poplar was not as stable as that in Chinese fir. Therefore, differences in tree species should be considered in low-concentration FA impregnation, as the improvement effect of concentrations below 10% on the properties of fast-growing wood is weak and the leaching rate of FA is significant.

In order to reduce the formaldehyde emission of formaldehyde-based wood adhesive from the source,it is aimed to develop a novel co-condensed resin of glyoxal-monomethylolurea-melamine(G-MMU-M).A series of G-MMU-M resins with various formulations of raw materials were successfully prepared.The basic properties and bonding performance of the G-MMU-M resins were determined.Furthermore,the structures of resins were characterized by FTIR, 13 C NMR,XPS,and ESI-MS.The results show that the prepared G-MMU-M resin remains stable for 30 d,meanwhile,the dry and wet bonding strength of the plywoods bonded with the resins,solid content and viscosity are influenced greatly by the addition amount of melamine and MMU/G molar ratio.The G-MMU-M resins with MMU/G molar ratio of 0.9:1.0and 8% melamine exhibit the highest dry and bonding strength of 1.98 MPa and 1.27 MPa,increased by 34% and 63%,respectively,in comparison with glyoxal-monomethylolurea(G-MMU) resin.In the G-MMU-M resins,there were four main oligomers including M—CH(— + CH-MMU)-O-MMU,M-CH(—CH 2 OH)-MMU-O-MMU,M—CH(—OH)— + CH-MMU-O-MMU,and M—CH(— + CH-MMU)-MMU-p-G.

正交胶合木(CLT)是一种新型的工程木,主要应用于木结构建筑方面,可作为楼板、墙体、地板等建筑构件.全球范围内,CLT是发展速度最快的林产品.本文简述了CLT在国外的发展历程,介绍了CLT的生产工艺;阐明CLT在国内的进一步发展需要社会各方面系统的支持;并且根据CLT在建筑中的发展,指出国内CLT的未来研究方向应该注重于降低成本、提高质量、CLT原料多元化和有自主知识产权的标准的建立.

为解决变温变湿状态下木材拉伸和压缩蠕变试验过程中普遍存在的试验环境难以控制、蠕变变形量难以测量、数据采集烦琐、设备长期运行稳定性较差等问题,依据木材拉伸及压缩力学性能的测试基本原理和相关国内外标准研制了 一套木材拉伸及压缩一体化蠕变自动监测系统.系统主要由软件系统和硬件系统两个部分组成,软件系统基于VB语言和查表算法进行开发,硬件系统包括蠕变测试环境系统、框架和受力导向系统、加载系统、拉伸和压缩蠕变测试的转换系统、试件夹装系统及数据采集系统、检测装置与环境系统的连接机架、信号接收和转换系统.该套系统的试验环境参数可调控范围为温度-10～70℃,相对湿度10％～98％,风速为0.3～5.6 m/s,蠕变变形量测试精度为0.001 mm,数据采集间隔1 s～24 h多梯度可调.经过前期14.6 d的木材拉伸蠕变测试和30 d的木材压缩蠕变试验检验,证明该系统可对木材的拉伸或压缩蠕变变形量进行长时间、稳定可靠和高精度的实时动态监测、记录和显示.同时,本次研究的拉压转化装置和加载装置大大降低了同类系统的总质量及试验操作的复杂性,为木材拉伸及压缩蠕变测试和研究提供了一个新的平台.

Furfurylation with a low concentration of furfuryl alcohol (FA) promotes the improvement of the properties and the effectiveness of FA on cell–wall action without darkening the furfurylated wood to the point that it affects its applications. In this paper, the effects of furfurylation on the hygroscopicity and water uptake dimensional stability of poplar (Populus sp.) and Chinese fir (Cunninghamia lanceolata) were analyzed. Meanwhile, the distribution of FA resin, the relationship between wood and water, the change in pore size distribution, and the weight percentage gain and cell wall bulking coefficient of wood were also investigated. The results were as follows: (1) A low concentration of FA could better enter the cell walls of the Chinese fir than the poplar, as FA resin was almost cured in the secondary walls, cell corners, and compound middle lamellae when a 10% concentration of FA was applied to the Chinese fir and poplar. When the FA concentration was increased to 30%, there were no significant increases in the amount of FA entering the cell walls and the amounts of FA cured in the cell lumen of the poplar were greater than those of the Chinese fir. Meanwhile, the modification of cell walls was more suitable in poplar than in Chinese fir. (2) The pointed ends of the pit chambers and the pit apertures (800–1000 nm) in the poplar and the small pores of the pit membranes and the pit apertures (1–6 μm) in the Chinese fir were partially deposited by the FA resin, which formed new pores in the size ranges of 80–600 nm and 15–100 nm, respectively. The porosity of the poplar was greater than that of the Chinese fir, and the bulk density of the poplar was less than that of the Chinese fir before and after modification. (3) Furfurylation with a low concentration of FA was able to better reduce the equilibrium moisture content, improve the anti-swelling efficiency, and enhance the dimensional stability of the poplar wood compared to the Chinese fir. Furfurylation effectively reduced water uptake due to the hydrophobic property of the FA resin. The water uptake of the Chinese fir increased by 17%–19% in second cyclic water soaking when treated with FA with various concentrations, which indicated the loss and leaching of FA resin during the test. Low-field NMR was used to demonstrate that the furfurylation not only reduced the amount of water but also affected the combination state of bound and free water with wood. Thus, furfurylation at a low concentration is a feasible method by which to extend applications of furfurylated wood.

为解决木材变湿蠕变测试普遍存在的环境参数(温湿度和风速)控制方式和控制精度不足、蠕变变形量测试灵敏度和精度不足、数据智能采集和处理以及系统安全防护不足等问题,在集成现有技术的基础上研发出一套木材蠕变测试系统.该系统包括环境气候箱、蠕变测试机架、木材蠕变变形量及干缩湿胀测试单元、荷载同时装卸单元、数据采集和处理单元、系统保障和防护单元6个部分.该系统可在温度为0～70 ℃、相对湿度为10％～98％、风速为0.3～5.6 m/s时对木材或木基材料的普通蠕变和机械吸附蠕变进行长时间稳定的测试、记录,蠕变变形量及木材厚度方向的干缩湿胀检测精度为±0.01 mm,数据采样间隔在1 s～24 h范围内可调.与现有木材蠕变测试系统相比,本系统在多参数自动同步获取、数据采样精度、运行稳定性、安全性和环境风速可调性等方面有独特优势.通过前期对木材112 d循环变湿蠕变量、干缩湿胀量及环境温湿度参数的观测和测试结果分析,证实该套检测系统可对木材的蠕变挠度、干缩湿胀量、环境温湿度等参数进行长期连续稳定的检测、记录和显示,所有测试指标均能达到设计预期.同时,由于该系统具有多参数协同检测和精度较高等特性,使得实测木材变湿蠕变比采用喷蒸变湿处理试件所获蠕变测试结果在局部地方存在明显差异,如吸湿过程中的木材静曲挠度并不都是反向减小,而是取决于吸湿速率和外荷载的竞争关系,从而为木材静曲变湿蠕变机理的揭示提供了有力证据.该系统的研制为精确可控变温变湿环境下太材蠕变机理的研究提供了新的平台.

为探究云南大理白族文化在现代旅居建筑设计中的运用,以期为旅居设计的未来发展提供理论性的支持.根据白族传统民居建筑设计与现代旅居建筑之间的相互关系意义,提出了在设计应用中重点表现白族建筑的文化元素.针对旅居建筑在民族地域文化中缺失本土特色以及同质化现象,从民族建筑保护创新的角度重新出发,对国内外旅居建筑案例进行调查研究.本着将白族民居文化运用于旅居设计的目的提出相应的符合现代建筑审美的设计原则与方法,在保留民族建筑文化的同时实现现代旅居文化的深层次发展.

虫眼、活节和死节是最常见的木材表面缺陷,是木材分选过程主要的识别目标,精确提取木材表面缺陷轮廓特征能大幅提高木材分选的准确率.本研究提出一种针对木材表面虫眼、活节、死节缺陷轮廓提取方法.针对木材表面常见黑点和纹理等非线性噪声,使用中值滤波方法平滑图像.然后分别应用OTSU算法与全局阈值分割算法分离图像背景与目标,对结果二值图像使用数学形态学方法进行滤除和填充,最终用sobel算子提取缺陷边缘.结果表明,采用OTSU算法分割和数学形态学相结合的方法可以很好地提取木材表面缺陷特征,用so bel算子能够提取到比较完整、准确、连续的木材表面缺陷边缘轮廓,提高了目标图像的可视性和精准性.

Moisture content (MC) and its variation have a significant influence on creep in wood. Therefore, reducing moisture absorptive/desorptive effect is one of the best means to minimize creep deformation in wood. Moreover, furfuration treatment of wood is one of the most economical methods to achieve this purpose. In this project, samples of Poplar wood (Populuseuramevicana) were treated with 30% furfuryl alcohol solution (furfurylated wood) and then tested for normal creep (NC) and mechanical sorptive creep (MSC) at different stress levels in several relative humidity (RH) conditions. Results from the experiment and analysis indicated that the normal creep performance of furfurylated wood was similar to that of classical untreated wood material. Nevertheless, furfurylated wood at different stress levels (less than 35%) or in different relative humidity environments did not follow MSC performance (i.e. creep deflection increases during moisture desorption while decreases during moisture absorption) of untreated wood and only exhibited wood NC characteristics (i.e. creep deflection increases continuously with time). Moreover, the maximum MSC deflection of furfurylated wood was 72.3% and 72.2% lower than that of untreated wood at the same 10% stress level and the same range of 65-98% relative humidity variation, respectively. The stress level was positively related to the deformations of instantaneous elastic, viscoelastic, viscous and bending creep, but negatively related to deformation of furfurylated wood creep recovery. Furthermore, it was also found that variation in RH did not have a significant impact on MSC deflection of furfurylated wood compared with untreated wood. The 4-element Burgers model and the 2-parameter Weibull distribution could well simulate the normal creep and creep-recovery responses respectively for furfurylated wood. (C) 2020 Elsevier Ltd. All rights reserved.