Using non-toxic,low-volatile glyoxal to completely replace formaldehyde for preparing urea-glyoxal(UG)resin adhesive is a hot research topic that could be of great interest for the wood industry.However,urea-glyoxal(U...Using non-toxic,low-volatile glyoxal to completely replace formaldehyde for preparing urea-glyoxal(UG)resin adhesive is a hot research topic that could be of great interest for the wood industry.However,urea-glyoxal(UG)resins prepared by just using glyoxal instead of formaldehyde usually yields a lower degree of polymerization.This results in a poorer bonding performance and water resistance of UG resins.A good solution is to pre-react urea to preform polyurea molecules presenting already a certain degree of polymerization,and then to condense these with glyoxal to obtain a novel UG resin.Therefore,in this present work,the urea was reacted with hexamethylene diamine to form a polyurea named HU,and then this was used to react it with different amounts of glyoxal to synthesize hexamethylenediamine-urea-glyoxal(HUG)polycondensation resins,and to use this for bonding plywood.The results show that the glyoxal can well react with HU polyuria via addition and schiff base reaction,and also the HUG resin exhibits excellent bonding strength and water resistance.The shear strength of the plywood bonded with this HUG at 160°C hot press temperature as high as 1.93 MPa,2.16 MPa and 1.61 MPa,respectively,which meets the requirement of the China national standard GB/T 9846-2015(≥0.7 MPa),and can be a good choice as a wood adhesive for industrial application.展开更多
Based on commercially available polyvinyl alcohol (PVA) stabilised polyvinyl acetate (PVAc), emulsion adhesives are neither heat nor moisture-resistant and show weak strength at high relative humidity and high tempera...Based on commercially available polyvinyl alcohol (PVA) stabilised polyvinyl acetate (PVAc), emulsion adhesives are neither heat nor moisture-resistant and show weak strength at high relative humidity and high temperatures. Pre- or post-crosslinking is another method used to manufacture a conventional vinyl-based homopolymers or copolymers system with improved water resistance. Vinyl neodecanoate (VeoVa), N-methylolacrylamide (NMA), Methacrylamide, methacrylic acid (MAA), and other self-crosslinking comonomers are typically inserted to produce highly water-resistant vinyl based homopolymers or copolymers. Additionally, organic crosslinkers like glyoxal, glutaraldehyde, citric acid, tartaric acid, and the like, as well as inorganic crosslinkers like acidic metal salts like aluminium chloride, aluminium nitrate, boric acid, and the like, can be used to prepare the highly water-resistant vinyl based homopolymers or copolymers. It is also possible to combine the self-crosslinking comonomers with the organic crosslinkers. Recently, a different hybrid chemistry has been developed that improves lap shear strength, has outstanding water resistance, good durability, and doesn’t require any additional crosslinker agents. Two distinct polymers were combined to develop hybrid polymers. They usually involve mixing an organic polymer with a polymer. There are many capping agents that are used for polyurethanes to produce acrylics that are capped with polyurethane and used as an oligomer in PVAc wood glue. Here, in this paper, we reviewed the different hybrid chemistry based on polyurethane chemistry for wood bonding applications.展开更多
Wooden buildings play a very important role in China’s construction and landscape architecture industry.In order to explore the weathering characteristics of the surface layer of landscape wooden buildings,the main c...Wooden buildings play a very important role in China’s construction and landscape architecture industry.In order to explore the weathering characteristics of the surface layer of landscape wooden buildings,the main causes of weathering were analyzed on the basis of summarizing the common types of weathering characterization.The results showed that the weathering characterization was mainly reflected in the surface defects of wood structures,such as cracking,discoloration,peeling,wind erosion wear,and so on.The coating technology on the surface of constructions was the main artificial factor affecting the surface defects of constructions.In the case of similar surface decoration conditions,sunlight and moisture were the main natural factors affecting the weathering of wooden buildings,which will promote the process of weathering.展开更多
Nowadays,wood identification is made by experts using hand lenses,wood atlases,and field manuals which take a lot of cost and time for the training process.The quantity and species must be strictly set up,and accurate...Nowadays,wood identification is made by experts using hand lenses,wood atlases,and field manuals which take a lot of cost and time for the training process.The quantity and species must be strictly set up,and accurate identification of the wood species must be made during exploitation to monitor trade and enforce regulations to stop illegal logging.With the development of science,wood identification should be supported with technology to enhance the perception of fairness of trade.An automatic wood identification system and a dataset of 50 commercial wood species from Asia are established,namely,wood anatomical images collected and used to train for the proposed model.In the convolutional neural network(CNN),the last layers are usually soft-max functions with dense layers.These layers contain the most parameters that affect the speed model.To reduce the number of parameters in the last layers of the CNN model and enhance the accuracy,the structure of the model should be optimized and developed.Therefore,a hybrid of convolutional neural network and random forest model(CNN-RF model)is introduced to wood identification.The accuracy’s hybrid model is more than 98%,and the processing speed is 3 times higher than the CNN model.The highest accuracy is 1.00 in some species,and the lowest is 0.92.These results show the excellent adaptability of the hybrid model in wood identification based on anatomical images.It also facilitates further investigations of wood cells and has implications for wood science.展开更多
The growth and wood properties of 240 individual Populus×euramericana cv.’74/76’(hereafter poplar 107)trees planted in Hebei Plain,China was evaluated.Mean annual increments in height,breast height diameter and...The growth and wood properties of 240 individual Populus×euramericana cv.’74/76’(hereafter poplar 107)trees planted in Hebei Plain,China was evaluated.Mean annual increments in height,breast height diameter and volume,as well as cellulose,hemicellulose and lignin contents,shrinkage,density,bending strength and modulus of elasticity in the heart wood and sap wood.Environmental factors influencing growth and wood properties were analyzed using correlation and stepwise regres sion.The results show that the coefficients of variation(CVs)of growth traits ranged from 10.6 to 22.4%.The CVs of the chemical properties of heartwood ranged from 4.3 to 30.2%,and for sap wood from 3.2 to 27.5%.The CVs of the physical and mechanical properties of heartwood ranged from 8.6 to 31.7%,and for sapwood from 6.4 to 29.9%.The results of one-way ANOVA showed that there were significant differences in growth traits and wood properties among sites.Soil pH,total and available phosphorus,total potassium,and soil organic matter were key soil factors affecting growth and wood properties of poplar 107,whereas mean annual ground temperatures and precipitation were the main climatic factors.To better cultivate poplar 107,area with less annual rainfall,slightly higher temperature and soil pH value close to neutral should be selected.展开更多
Wood plays a major role in the production of furniture and wooden structures.Nevertheless,in this process,the massive use of adhesives and plural connectors remains a definite problem for health and the environment.Th...Wood plays a major role in the production of furniture and wooden structures.Nevertheless,in this process,the massive use of adhesives and plural connectors remains a definite problem for health and the environment.Therefore,wood welding is a breakthrough in this respect.This paper reviews the applications of wood welding in furniture and construction and then examines advances in improving the durability of welded wood against water.Our contribution also highlights the need to join African tropical woods using the rotational friction welding technique.According to our results,these woods present interesting chemical singularities,which could provide solutions to the water vulnerability of the welded wood.Moreover,the use of such a joining method would first free the Cameroonian furniture industry from the chemical industry,secondly position it at the forefront of new eco-design trends and thirdly make it competitive with other countries in the Central African sub-region.These works enrich the long and rich bibliography on the technique of wood welding,which has long been conspicuous by its absence of tropical woods.展开更多
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 euramevic...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.展开更多
Wood is a lignocellulosic material that,because of its organic nature,is a source of nutrients for bacteria,fungi,and insects.Incisitermes marginipennis(Latreille)is an interesting dry wood-boring termite.Because it i...Wood is a lignocellulosic material that,because of its organic nature,is a source of nutrients for bacteria,fungi,and insects.Incisitermes marginipennis(Latreille)is an interesting dry wood-boring termite.Because it is an extremely destructive pest,difficult to control due to its cryptic lifestyle,and for its role in the biogeochemical cycle of carbon and other elements;it is a fundamental organism.The use of less toxic and eco-friendly substances is important for protecting domestic,cultural,and historical heritage made of wood or lignocellulosic materials.The aim of this study was to evaluate the biological activity of various naphthoquinones extracted from the heartwood of T.grandis on I.marginipennis.First,heartwood flour was used for Soxhlet-type extractions to isolate and characterize the heartwood compounds by thin-layer chromatography.To identify the heartwood compounds,nuclear magnetic resonance and gas chromatography coupled to a mass spectrometer were used.The information obtained was supported using the Interactive Spectroscopy software.The identified heartwood compounds were lapachol,tectoquinone,deoxylapachol,dehydro-α-lapachone,tectol and tecomaquinone-I.Using nymphal termites of I.marginipennis as a biological model,the isolated and identified molecules were under three different tests(repellent,insecticide and protective)and their biological activity was individually evaluated.The results showed that the molecules obtained have a repellent-protective effect against I.marginipennis,although not in all cases,these molecules have high percentages of mortality and decreased the weight loss of the treated material exposed to I.marginipennis.展开更多
This research investigates the efficacy of activated Gmelina Wood Sawdust (GWS) as an adsorbent for the removal of methylene blue (MB) dye from aqueous solutions, in comparison with raw GWS. The study employs laborato...This research investigates the efficacy of activated Gmelina Wood Sawdust (GWS) as an adsorbent for the removal of methylene blue (MB) dye from aqueous solutions, in comparison with raw GWS. The study employs laboratory experiments to assess the percentage of dye removal across various temperature and pH conditions. The adsorption process is scrutinized under different parameters, encompassing contact time, initial dye concentration, adsorbent dosage, temperature, and pH. Results demonstrate that activated GWS surpasses its raw counterpart, showcasing superior MB dye removal percentages. Extended contact times increased initial dye concentrations, and higher adsorbent dosages contribute positively to removal efficiency, while temperature exhibits an inverse relationship with dye removal. Optimal adsorption occurs at a pH of 7.0, aligning with the adsorbent’s zero-point charge (pHzpc), underscoring the role of surface charge in the adsorption process. This study underscores the potential of activated GWS as an economical and promising adsorbent material for addressing pollutants. Furthermore, the utilization of activated carbon derived from abundant agricultural waste underscores an environmentally conscious approach to adsorption applications. The ability to tailor the size and properties of activated carbon particles opens avenues for optimizing adsorption capabilities, thereby presenting opportunities for enhanced water treatment solutions.展开更多
Biomass adhesive is conducive to decreasing the dependence of the wood adhesive industry on synthetic resin based on fossil resources and improving the market competitiveness of adhesives.It is also a critical breakth...Biomass adhesive is conducive to decreasing the dependence of the wood adhesive industry on synthetic resin based on fossil resources and improving the market competitiveness of adhesives.It is also a critical breakthrough to realize the goal of carbon peaking and carbon neutrality in the wood industry.In this study,a full biomass wood adhesive composed of tannin and sucrose was developed and applied successfully to the preparation of ply-wood.The preparation technique of plywood was optimized,and the chemical structure,curing performance,crystallization property and thermal performance of the adhesive were investigated.Results showed that:(1)hot-pressing temperature played a decisive role in the performances of tannin-sucrose composite adhesives and it also had a very significant influence on the water resistance of plywood.(2)The preparation of tannin-sucrose composite adhesive was a process in which sucrose was transformed into furan aldehydes and then made cross-linking reaction with tannin.These composite adhesives could only get good bonding performances when the curing temperature was above 210℃.(3)The optimal plywood preparation technique was:hot-pressing tem-perature of 220℃,hot-pressing time of 1.2 min/mm,m(tannin):m(sucrose)of 60:40,and adhesive loading of 160 g/m^(2).The wet bonding strength in boiling water of the prepared plywood was 0.83 MPa,meeting the strength requirements of Type-I plywood in the standard of GB/T 17657-2013.(4)The curing temperature of tannin-sucrose composite adhesive was further decreased by lowering the temperature during the transformation of sucrose into 5-HMF,which was a key in subsequent research.展开更多
Studies presenting long-term observations of the recruitment and mobility of large wood in mountain watercourses are scarce,but they can considerably contribute to the knowledge of river/riparian forest interactions a...Studies presenting long-term observations of the recruitment and mobility of large wood in mountain watercourses are scarce,but they can considerably contribute to the knowledge of river/riparian forest interactions and the assessment of flood hazard resulting from wood mobility during floods.Widespread dieback of riparian forest along the headwater course of Kamienica Stream in the Polish Carpathians,caused by bark beetle infestation of spruce trees,has raised concerns about potential increases of large wood recruitment to the stream and of the flood hazard to downstream valley reaches.In October 2009,429 trees growing along three sections of the stream were tagged with numbered metal plates and monitored over 10 years to determine the timing and causes of their delivery to the channel and the lengths of their displacement during individual flood events.Moreover,in 2012 the mode of location of wood deposits and a degree of wood decay were determined in the second-to fourth-order stream reaches.The monitoring of tagged trees indicated that trees were recruited to the channel during highintensity meteorological and hydrological events,mostly as a result of bank erosion during floods or windthrow.With 22%of tagged trees recruited to the channel during 10 years,the rate of turnover of the riparian trees was estimated at 45 years.As the riparian area is overgrown with trees with ages up to^160 years,the rate evidences substantial intensification of large wood recruitment to the channel in the recent period.Results of large wood inventory and the 10-year-long monitoring of tagged trees indicated variable mobility of large wood along the upper course of the stream.Wood mobility was negligible in the second-order stream reach,very small in the third-order reach,and greater,but still limited in the fourth-order reach.Wood is transported longer distances only during major floods.However,the advanced state of decay of most pieces leads to their disintegration during floods,precluding distant transport.Thus,large wood retained in the upper stream course does not constitute an important flood hazard to downstream,inhabited valley reaches.展开更多
The aim of this research work was to evaluate the potential of using renewable natural feedstock,i.e.,Jatropha curcas oil(JCO)for the synthesis of non-isocyanate polyurethane(NIPU)resin for wood composite applications...The aim of this research work was to evaluate the potential of using renewable natural feedstock,i.e.,Jatropha curcas oil(JCO)for the synthesis of non-isocyanate polyurethane(NIPU)resin for wood composite applications.Commercial polyurethane(PU)is synthesized through a polycondensation reaction between isocyanate and poly-ol.However,utilizing toxic and unsustainable isocyanates for obtaining PU could contribute to negative impacts on the environment and human health.Therefore,the development of PU from eco-friendly and sustainable resources without the isocyanate route is required.In this work,tetra-n-butyl ammonium bromide was used as the activator to open the epoxy ring with 3-Aminopropyltriethoxisylane as a catalyst to yield urethane of JCO(UJCO).The UJCO were characterized by Fourier Transform Infra-Red spectroscopy(FTIR)and their oxirane,and hydroxyl values were measured.The result showed that a decrease in oxirane value was found while the hydroxyl value was increased during the time,confirming that the urethane group was formed.The presence of functional groups in FTIR spectra at wave numbers 1732.08,1562.34,and 3348.42 cm^(−1) indicates the functional groups of C=O(urethane carbonyl),–NH,and–OH,respectively confirmed this finding.The potential applications of NIPU in the wood composite were also outlined.展开更多
Conferring surfaces with superhydrophilic/superaerophobic characteristics is desirable for synthesizing efficient gas reaction catalysts.However,complicated procedures,high costs,and poor interfaces hinder commerciali...Conferring surfaces with superhydrophilic/superaerophobic characteristics is desirable for synthesizing efficient gas reaction catalysts.However,complicated procedures,high costs,and poor interfaces hinder commercialization.Here,an integrated electrode with tunable wettability derived from a hierarchically porous wood scaffold was well designed for urea oxidation reaction(UOR).Interestingly,the outer surface of the wood lumen was optimized to the preferred wettability via stoichiometry to promote electrolyte permeation and gas escape.This catalyst exhibits outstanding activity and durability for UOR in alkaline media,requiring only a potential of 1.36 V(vs.RHE)to deliver 10 m A cm^(-2)and maintain its activity without significant decay for 60 h.These experiments and theoretical calculations demonstrate that the nickel(oxy)hydroxide layer formed through surface reconstruction of nickel nanoparticles improves the active sites and intrinsic activity.Moreover,the superwetting properties of the electrode promote mass transfer by guaranteeing substantial contact with the electrolyte and accelerating the separation of gaseous products during electrocatalysis.These findings provide the understanding needed to manipulate the surface wettability through rational design and fabrication of efficient electrocatalysts for gas-evolving processes.展开更多
The co-pyrolysis of coal and biomass has proven to be a promising route to produce liquid and gaseous fuels as well as specific value-added chemicals while contributing to mitigating CO_(2) emissions.The interactions ...The co-pyrolysis of coal and biomass has proven to be a promising route to produce liquid and gaseous fuels as well as specific value-added chemicals while contributing to mitigating CO_(2) emissions.The interactions between the co-processed feedstocks,however,need to be elucidated to support the development of such a thermochemical conversion process.In this context,the present work covers the kinetic analysis of the co-pyrolysis of a bituminous coal with poplar wood.In this research,biomass was blended with coal at two different mass ratios(10%(mass)and 20%(mass)).Thermogravimetric analyses were carried out with pure and blended samples at four heating rates(5,10,15 and 30℃·min^(-1)).A direct comparison of experimental and theoretical results(based on a simple additivity rule)failed to yield a clear-cut conclusion regarding the existence of synergistic effects.Kinetic analyses have therefore been achieved using two model-free methods(the Ozawa-Flynn-Wall and Kissinger-Akahira-Sunose models)to estimate the rate constant parameters related to the pyrolysis process.A significant decrease of the activation energy has thus been observed when adding wood to coal(activation energies associated with the blend containing 20%(mass)of biomass being even lower than those estimated for pure wood at low conversion degrees).This trend was attributed to the possible presence of synergies whose related mechanisms are discussed.The rate constant parameters derived by means of the two tested models were finally used to simulate the evolution of the conversion degree of each sample as a function of the temperature,thus leading to a satisfying agreement between measured and simulated data.展开更多
Rarely,penetrating injuries to the spinal cord result from wooden objects,creating unique challenges to mitigate neurological injury and high rates of infection and foreign body reactions.We report a man who sustained...Rarely,penetrating injuries to the spinal cord result from wooden objects,creating unique challenges to mitigate neurological injury and high rates of infection and foreign body reactions.We report a man who sustained a penetrating cervical spinal cord injury from a sharpened stick.While initially tetraparetic,he rapidly recovered function.The risks of neurological deterioration during surgical removal made the patient reluctant to consent to surgery despite the impalement of the spinal cord.A repeat MRI on day 3 showed an extension of edema indicating progressive inflammation.On the 7~(th)day after injury,fever and paresthesias occurred with a large increase in serum inflammatory indicators,and the patient agreed to undergo surgical removal of the wooden object.We discuss the management nuances related to wood,the longitudinal evolution of MRI findings,infection risk,surgical risk mitigation and technique,an inflammatory marker profile,long-term recovery,and the surprisingly minimal neurological deficits associated with low-velocity midline spinal cord injuries.The patient had an excellent clinical outcome.The main lessons are that a wooden penetrating central nervous system injury has a high risk for infection,and that surgical removal from the spinal cord should be performed soon after injury and under direct visualization.展开更多
Various crosslinking agents can be added to the formulations of natural-based adhesives for wood bonding in order to achieve better durability and higher strength of the formed joints.In the present study,the effect o...Various crosslinking agents can be added to the formulations of natural-based adhesives for wood bonding in order to achieve better durability and higher strength of the formed joints.In the present study,the effect of hexamethylenediamine(HMDA)addition on the performance of liquefied wood(LW)adhesive for wood bonding is investigated.Differential scanning calorimetry showed the improved thermal stability and crosslinking of the LW adhesive with HMDA.The intensified presence of amide linkages(C–N bonds)was found in LW+HMDA with attenuated total reflection Fourier transform infrared spectroscopy.Analysis of the bonded joints using an automated bonding evaluation system showed that a higher press temperature resulted in stronger bonds for both types of adhesives.Moreover,the addition of HMDA to LW adhesive improved the bond strength of the joints and accelerated the crosslinking of the adhesive.However,with a tensile shear strength of(6.76±2.16)N×mm^(−2)(for LW)and(6.89±2.10)N×mm^(−2)(for LW+HMDA),both adhesives were found to be unsuitable for interior non-structural use.In addition,the acidity of LW resulted in relatively high wood failure(70%)in the adhesive joints tested.Improved crosslinking of LW with HMDA was reflected in improved resistance of LW+HMDA adhesive joints to water degradation.In conclusion,HMDA is a promising additive for improving the adhesive performance of LW adhesives.展开更多
This study aims to improve the value of fast-growing wood and extend the heat-treated wood utilization using inorganic calcium carbonate(CaCO_(3))crystals via an in-situ synthesis method.CaCl_(2)and Na 2CO_(3)solution...This study aims to improve the value of fast-growing wood and extend the heat-treated wood utilization using inorganic calcium carbonate(CaCO_(3))crystals via an in-situ synthesis method.CaCl_(2)and Na 2CO_(3)solutions with a concentration ratio of 1:1 were successively introduced into the thermally modified poplar wood obtained by steam heat treatment(HT)at 200℃for 1.5 and 3 h,resulting in the in-situ synthesis of CaCO_(3)crystals inside the heat-treated wood.The filling effect was best at the concentration of 1.2 mol/L.CaCO_(3)was uniformly distributed in the cell cavities of the heat-treated wood,and some of the crystals were embedded in the fissures of the wood cell walls.The morphology of CaCO_(3)crystals was mainly spherical and rhombic polyhedral.Three main types of CaCO_(3)crystals were calcite,vaterite,and aragonite.The HT of poplar wood at 200℃resulted in degrading the chemical components of the wood cell wall.This degradation led to reduced wood mechanical properties,including the surface hardness(HD),modulus of rupture(MOR),and modulus of elasticity(MOE).After CaCO_(3)was in-situ synthesized in the heat-treated wood,the HD increased by 18.36%and 16.35%,and MOR increased by 14.64%and 8.89%,respectively.Because of the CaCO_(3)synthesization,the char residue of the 200℃heat-treated wood samples increased by 9.31%and the maximum weight loss rate decreased by 19.80%,indicating that the filling with CaCO_(3)cannot only improve the mechanical properties of the heat-treated wood but also effectively enhance its thermal stability.展开更多
Drying crack is a common phenomenon occurring during moisture discharge from wood,reducing efficient wood utilization.Drying crack is primarily caused by drying stress,and the reasonable methods for determining drying...Drying crack is a common phenomenon occurring during moisture discharge from wood,reducing efficient wood utilization.Drying crack is primarily caused by drying stress,and the reasonable methods for determining drying stress are sparse.In this study,the initiation and propagation of cracks during wood discs drying were simulated using the extended finite element method(XFEM).The distribution of drying stress and displacement was analyzed at different crack conditions based on the simulation results.This study aimed to solve the problem of the limitation of drying stress testing methods and provide a new idea for the study of wood drying stress.The numerical simulation results are found in good agreement with the experimental results,thus corroborating the feasibility of XFEM in modeling drying crack of wood discs.The stress concentration was observed at the crack tip region,while a minor stress was presented in the region of crack passing through,indicating that the crack formation process was also a process of releasing drying stress.Further,more energy was required to form double cracks in comparison with the single crack mode.展开更多
This article presents the first applied results of using citric acid in combinations with a melamine-urea-formal-dehyde(MUF)resin for bonding wood veneers.The chemical reactions involved are shown based on a MALDI ToF...This article presents the first applied results of using citric acid in combinations with a melamine-urea-formal-dehyde(MUF)resin for bonding wood veneers.The chemical reactions involved are shown based on a MALDI ToF analysis of the reaction of the MUF resin with citric acid.The preliminary results of the physical and mechanical properties of the LVL prepared are also presented.Veneers from Populus sp were used to manufacture 5-layer laminated veneer lumber(LVL)of small dimensions.Five combinations of the amount of citric acid,MUF spread rate and pressing parameters were tested.LVL bonded with 20%of citric acid+100 g/m^(2)of MUF,hot-pressed using a 3-step process with maximum 1.5 MPa of pressure yielded the board with better dimensional stability and mechanical properties.It could be concluded that citric acid in combination with MUF can be used for bonding wood veneer and the research should be continued to study further the parameters involved and to enhance the results.展开更多
基金supported by the Yunnan Provincial Natural Science Foundation (202201AU070222,202201AT070045,202101BD070001-074)Scientific Research Fund Project of Yunnan Provincial Department of Education (2022J0490)financed by the 111 Project (D21027).
文摘Using non-toxic,low-volatile glyoxal to completely replace formaldehyde for preparing urea-glyoxal(UG)resin adhesive is a hot research topic that could be of great interest for the wood industry.However,urea-glyoxal(UG)resins prepared by just using glyoxal instead of formaldehyde usually yields a lower degree of polymerization.This results in a poorer bonding performance and water resistance of UG resins.A good solution is to pre-react urea to preform polyurea molecules presenting already a certain degree of polymerization,and then to condense these with glyoxal to obtain a novel UG resin.Therefore,in this present work,the urea was reacted with hexamethylene diamine to form a polyurea named HU,and then this was used to react it with different amounts of glyoxal to synthesize hexamethylenediamine-urea-glyoxal(HUG)polycondensation resins,and to use this for bonding plywood.The results show that the glyoxal can well react with HU polyuria via addition and schiff base reaction,and also the HUG resin exhibits excellent bonding strength and water resistance.The shear strength of the plywood bonded with this HUG at 160°C hot press temperature as high as 1.93 MPa,2.16 MPa and 1.61 MPa,respectively,which meets the requirement of the China national standard GB/T 9846-2015(≥0.7 MPa),and can be a good choice as a wood adhesive for industrial application.
文摘Based on commercially available polyvinyl alcohol (PVA) stabilised polyvinyl acetate (PVAc), emulsion adhesives are neither heat nor moisture-resistant and show weak strength at high relative humidity and high temperatures. Pre- or post-crosslinking is another method used to manufacture a conventional vinyl-based homopolymers or copolymers system with improved water resistance. Vinyl neodecanoate (VeoVa), N-methylolacrylamide (NMA), Methacrylamide, methacrylic acid (MAA), and other self-crosslinking comonomers are typically inserted to produce highly water-resistant vinyl based homopolymers or copolymers. Additionally, organic crosslinkers like glyoxal, glutaraldehyde, citric acid, tartaric acid, and the like, as well as inorganic crosslinkers like acidic metal salts like aluminium chloride, aluminium nitrate, boric acid, and the like, can be used to prepare the highly water-resistant vinyl based homopolymers or copolymers. It is also possible to combine the self-crosslinking comonomers with the organic crosslinkers. Recently, a different hybrid chemistry has been developed that improves lap shear strength, has outstanding water resistance, good durability, and doesn’t require any additional crosslinker agents. Two distinct polymers were combined to develop hybrid polymers. They usually involve mixing an organic polymer with a polymer. There are many capping agents that are used for polyurethanes to produce acrylics that are capped with polyurethane and used as an oligomer in PVAc wood glue. Here, in this paper, we reviewed the different hybrid chemistry based on polyurethane chemistry for wood bonding applications.
基金Science and technology research projects of colleges and universities in Inner Mongolia(NJZY22511)Funds for basic scientific research in universities of Inner Mongolia:Key project of Philosophy and Social Science Foundation of Inner Mongolia Agricultural University(BR220603)。
文摘Wooden buildings play a very important role in China’s construction and landscape architecture industry.In order to explore the weathering characteristics of the surface layer of landscape wooden buildings,the main causes of weathering were analyzed on the basis of summarizing the common types of weathering characterization.The results showed that the weathering characterization was mainly reflected in the surface defects of wood structures,such as cracking,discoloration,peeling,wind erosion wear,and so on.The coating technology on the surface of constructions was the main artificial factor affecting the surface defects of constructions.In the case of similar surface decoration conditions,sunlight and moisture were the main natural factors affecting the weathering of wooden buildings,which will promote the process of weathering.
文摘Nowadays,wood identification is made by experts using hand lenses,wood atlases,and field manuals which take a lot of cost and time for the training process.The quantity and species must be strictly set up,and accurate identification of the wood species must be made during exploitation to monitor trade and enforce regulations to stop illegal logging.With the development of science,wood identification should be supported with technology to enhance the perception of fairness of trade.An automatic wood identification system and a dataset of 50 commercial wood species from Asia are established,namely,wood anatomical images collected and used to train for the proposed model.In the convolutional neural network(CNN),the last layers are usually soft-max functions with dense layers.These layers contain the most parameters that affect the speed model.To reduce the number of parameters in the last layers of the CNN model and enhance the accuracy,the structure of the model should be optimized and developed.Therefore,a hybrid of convolutional neural network and random forest model(CNN-RF model)is introduced to wood identification.The accuracy’s hybrid model is more than 98%,and the processing speed is 3 times higher than the CNN model.The highest accuracy is 1.00 in some species,and the lowest is 0.92.These results show the excellent adaptability of the hybrid model in wood identification based on anatomical images.It also facilitates further investigations of wood cells and has implications for wood science.
基金supported by the National Key Research and Development Program of China(Grant Nos.2021YFD22012052016YFD0600400)。
文摘The growth and wood properties of 240 individual Populus×euramericana cv.’74/76’(hereafter poplar 107)trees planted in Hebei Plain,China was evaluated.Mean annual increments in height,breast height diameter and volume,as well as cellulose,hemicellulose and lignin contents,shrinkage,density,bending strength and modulus of elasticity in the heart wood and sap wood.Environmental factors influencing growth and wood properties were analyzed using correlation and stepwise regres sion.The results show that the coefficients of variation(CVs)of growth traits ranged from 10.6 to 22.4%.The CVs of the chemical properties of heartwood ranged from 4.3 to 30.2%,and for sap wood from 3.2 to 27.5%.The CVs of the physical and mechanical properties of heartwood ranged from 8.6 to 31.7%,and for sapwood from 6.4 to 29.9%.The results of one-way ANOVA showed that there were significant differences in growth traits and wood properties among sites.Soil pH,total and available phosphorus,total potassium,and soil organic matter were key soil factors affecting growth and wood properties of poplar 107,whereas mean annual ground temperatures and precipitation were the main climatic factors.To better cultivate poplar 107,area with less annual rainfall,slightly higher temperature and soil pH value close to neutral should be selected.
文摘Wood plays a major role in the production of furniture and wooden structures.Nevertheless,in this process,the massive use of adhesives and plural connectors remains a definite problem for health and the environment.Therefore,wood welding is a breakthrough in this respect.This paper reviews the applications of wood welding in furniture and construction and then examines advances in improving the durability of welded wood against water.Our contribution also highlights the need to join African tropical woods using the rotational friction welding technique.According to our results,these woods present interesting chemical singularities,which could provide solutions to the water vulnerability of the welded wood.Moreover,the use of such a joining method would first free the Cameroonian furniture industry from the chemical industry,secondly position it at the forefront of new eco-design trends and thirdly make it competitive with other countries in the Central African sub-region.These works enrich the long and rich bibliography on the technique of wood welding,which has long been conspicuous by its absence of tropical woods.
基金The present work was financially sponsored by the National Natural Science Foundation of China(Grant No.31960291).
文摘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.
基金supported by the Coordination of Scientific Research,UMSNH(Project 2022).
文摘Wood is a lignocellulosic material that,because of its organic nature,is a source of nutrients for bacteria,fungi,and insects.Incisitermes marginipennis(Latreille)is an interesting dry wood-boring termite.Because it is an extremely destructive pest,difficult to control due to its cryptic lifestyle,and for its role in the biogeochemical cycle of carbon and other elements;it is a fundamental organism.The use of less toxic and eco-friendly substances is important for protecting domestic,cultural,and historical heritage made of wood or lignocellulosic materials.The aim of this study was to evaluate the biological activity of various naphthoquinones extracted from the heartwood of T.grandis on I.marginipennis.First,heartwood flour was used for Soxhlet-type extractions to isolate and characterize the heartwood compounds by thin-layer chromatography.To identify the heartwood compounds,nuclear magnetic resonance and gas chromatography coupled to a mass spectrometer were used.The information obtained was supported using the Interactive Spectroscopy software.The identified heartwood compounds were lapachol,tectoquinone,deoxylapachol,dehydro-α-lapachone,tectol and tecomaquinone-I.Using nymphal termites of I.marginipennis as a biological model,the isolated and identified molecules were under three different tests(repellent,insecticide and protective)and their biological activity was individually evaluated.The results showed that the molecules obtained have a repellent-protective effect against I.marginipennis,although not in all cases,these molecules have high percentages of mortality and decreased the weight loss of the treated material exposed to I.marginipennis.
文摘This research investigates the efficacy of activated Gmelina Wood Sawdust (GWS) as an adsorbent for the removal of methylene blue (MB) dye from aqueous solutions, in comparison with raw GWS. The study employs laboratory experiments to assess the percentage of dye removal across various temperature and pH conditions. The adsorption process is scrutinized under different parameters, encompassing contact time, initial dye concentration, adsorbent dosage, temperature, and pH. Results demonstrate that activated GWS surpasses its raw counterpart, showcasing superior MB dye removal percentages. Extended contact times increased initial dye concentrations, and higher adsorbent dosages contribute positively to removal efficiency, while temperature exhibits an inverse relationship with dye removal. Optimal adsorption occurs at a pH of 7.0, aligning with the adsorbent’s zero-point charge (pHzpc), underscoring the role of surface charge in the adsorption process. This study underscores the potential of activated GWS as an economical and promising adsorbent material for addressing pollutants. Furthermore, the utilization of activated carbon derived from abundant agricultural waste underscores an environmentally conscious approach to adsorption applications. The ability to tailor the size and properties of activated carbon particles opens avenues for optimizing adsorption capabilities, thereby presenting opportunities for enhanced water treatment solutions.
文摘Biomass adhesive is conducive to decreasing the dependence of the wood adhesive industry on synthetic resin based on fossil resources and improving the market competitiveness of adhesives.It is also a critical breakthrough to realize the goal of carbon peaking and carbon neutrality in the wood industry.In this study,a full biomass wood adhesive composed of tannin and sucrose was developed and applied successfully to the preparation of ply-wood.The preparation technique of plywood was optimized,and the chemical structure,curing performance,crystallization property and thermal performance of the adhesive were investigated.Results showed that:(1)hot-pressing temperature played a decisive role in the performances of tannin-sucrose composite adhesives and it also had a very significant influence on the water resistance of plywood.(2)The preparation of tannin-sucrose composite adhesive was a process in which sucrose was transformed into furan aldehydes and then made cross-linking reaction with tannin.These composite adhesives could only get good bonding performances when the curing temperature was above 210℃.(3)The optimal plywood preparation technique was:hot-pressing tem-perature of 220℃,hot-pressing time of 1.2 min/mm,m(tannin):m(sucrose)of 60:40,and adhesive loading of 160 g/m^(2).The wet bonding strength in boiling water of the prepared plywood was 0.83 MPa,meeting the strength requirements of Type-I plywood in the standard of GB/T 17657-2013.(4)The curing temperature of tannin-sucrose composite adhesive was further decreased by lowering the temperature during the transformation of sucrose into 5-HMF,which was a key in subsequent research.
基金financed by the statutory funds of the Institute of Nature Conservation,Polish Academy of Sciencesby the project FLORIST(Flood risk on the northern foothills of the Tatra MountainsPSPB no 153/2010)supported by a grant from Switzerland through the Swiss Contribution to the Enlarged European Union。
文摘Studies presenting long-term observations of the recruitment and mobility of large wood in mountain watercourses are scarce,but they can considerably contribute to the knowledge of river/riparian forest interactions and the assessment of flood hazard resulting from wood mobility during floods.Widespread dieback of riparian forest along the headwater course of Kamienica Stream in the Polish Carpathians,caused by bark beetle infestation of spruce trees,has raised concerns about potential increases of large wood recruitment to the stream and of the flood hazard to downstream valley reaches.In October 2009,429 trees growing along three sections of the stream were tagged with numbered metal plates and monitored over 10 years to determine the timing and causes of their delivery to the channel and the lengths of their displacement during individual flood events.Moreover,in 2012 the mode of location of wood deposits and a degree of wood decay were determined in the second-to fourth-order stream reaches.The monitoring of tagged trees indicated that trees were recruited to the channel during highintensity meteorological and hydrological events,mostly as a result of bank erosion during floods or windthrow.With 22%of tagged trees recruited to the channel during 10 years,the rate of turnover of the riparian trees was estimated at 45 years.As the riparian area is overgrown with trees with ages up to^160 years,the rate evidences substantial intensification of large wood recruitment to the channel in the recent period.Results of large wood inventory and the 10-year-long monitoring of tagged trees indicated variable mobility of large wood along the upper course of the stream.Wood mobility was negligible in the second-order stream reach,very small in the third-order reach,and greater,but still limited in the fourth-order reach.Wood is transported longer distances only during major floods.However,the advanced state of decay of most pieces leads to their disintegration during floods,precluding distant transport.Thus,large wood retained in the upper stream course does not constitute an important flood hazard to downstream,inhabited valley reaches.
文摘The aim of this research work was to evaluate the potential of using renewable natural feedstock,i.e.,Jatropha curcas oil(JCO)for the synthesis of non-isocyanate polyurethane(NIPU)resin for wood composite applications.Commercial polyurethane(PU)is synthesized through a polycondensation reaction between isocyanate and poly-ol.However,utilizing toxic and unsustainable isocyanates for obtaining PU could contribute to negative impacts on the environment and human health.Therefore,the development of PU from eco-friendly and sustainable resources without the isocyanate route is required.In this work,tetra-n-butyl ammonium bromide was used as the activator to open the epoxy ring with 3-Aminopropyltriethoxisylane as a catalyst to yield urethane of JCO(UJCO).The UJCO were characterized by Fourier Transform Infra-Red spectroscopy(FTIR)and their oxirane,and hydroxyl values were measured.The result showed that a decrease in oxirane value was found while the hydroxyl value was increased during the time,confirming that the urethane group was formed.The presence of functional groups in FTIR spectra at wave numbers 1732.08,1562.34,and 3348.42 cm^(−1) indicates the functional groups of C=O(urethane carbonyl),–NH,and–OH,respectively confirmed this finding.The potential applications of NIPU in the wood composite were also outlined.
基金financially supported by the National Natural Science Foundation of China(31922057)the Young Elite Scientists Sponsorship Program from National Forestry and Grassland Administration of China(2019132614)+2 种基金the Outstanding Innovative Youth Training Program of Changsha(KQ2106050)The Hunan Provincial Innovation Foundation for Postgraduate(CX20210847)the Scientific Innovation Fund for Graduate of Central South University of Forestry and Technology(CX202101019)。
文摘Conferring surfaces with superhydrophilic/superaerophobic characteristics is desirable for synthesizing efficient gas reaction catalysts.However,complicated procedures,high costs,and poor interfaces hinder commercialization.Here,an integrated electrode with tunable wettability derived from a hierarchically porous wood scaffold was well designed for urea oxidation reaction(UOR).Interestingly,the outer surface of the wood lumen was optimized to the preferred wettability via stoichiometry to promote electrolyte permeation and gas escape.This catalyst exhibits outstanding activity and durability for UOR in alkaline media,requiring only a potential of 1.36 V(vs.RHE)to deliver 10 m A cm^(-2)and maintain its activity without significant decay for 60 h.These experiments and theoretical calculations demonstrate that the nickel(oxy)hydroxide layer formed through surface reconstruction of nickel nanoparticles improves the active sites and intrinsic activity.Moreover,the superwetting properties of the electrode promote mass transfer by guaranteeing substantial contact with the electrolyte and accelerating the separation of gaseous products during electrocatalysis.These findings provide the understanding needed to manipulate the surface wettability through rational design and fabrication of efficient electrocatalysts for gas-evolving processes.
基金the support of the French Ministry of Higher Education,Research and Innovation(Ministère de l’Enseignement supérieur,de la Recherche et de l’Innovation)。
文摘The co-pyrolysis of coal and biomass has proven to be a promising route to produce liquid and gaseous fuels as well as specific value-added chemicals while contributing to mitigating CO_(2) emissions.The interactions between the co-processed feedstocks,however,need to be elucidated to support the development of such a thermochemical conversion process.In this context,the present work covers the kinetic analysis of the co-pyrolysis of a bituminous coal with poplar wood.In this research,biomass was blended with coal at two different mass ratios(10%(mass)and 20%(mass)).Thermogravimetric analyses were carried out with pure and blended samples at four heating rates(5,10,15 and 30℃·min^(-1)).A direct comparison of experimental and theoretical results(based on a simple additivity rule)failed to yield a clear-cut conclusion regarding the existence of synergistic effects.Kinetic analyses have therefore been achieved using two model-free methods(the Ozawa-Flynn-Wall and Kissinger-Akahira-Sunose models)to estimate the rate constant parameters related to the pyrolysis process.A significant decrease of the activation energy has thus been observed when adding wood to coal(activation energies associated with the blend containing 20%(mass)of biomass being even lower than those estimated for pure wood at low conversion degrees).This trend was attributed to the possible presence of synergies whose related mechanisms are discussed.The rate constant parameters derived by means of the two tested models were finally used to simulate the evolution of the conversion degree of each sample as a function of the temperature,thus leading to a satisfying agreement between measured and simulated data.
文摘Rarely,penetrating injuries to the spinal cord result from wooden objects,creating unique challenges to mitigate neurological injury and high rates of infection and foreign body reactions.We report a man who sustained a penetrating cervical spinal cord injury from a sharpened stick.While initially tetraparetic,he rapidly recovered function.The risks of neurological deterioration during surgical removal made the patient reluctant to consent to surgery despite the impalement of the spinal cord.A repeat MRI on day 3 showed an extension of edema indicating progressive inflammation.On the 7~(th)day after injury,fever and paresthesias occurred with a large increase in serum inflammatory indicators,and the patient agreed to undergo surgical removal of the wooden object.We discuss the management nuances related to wood,the longitudinal evolution of MRI findings,infection risk,surgical risk mitigation and technique,an inflammatory marker profile,long-term recovery,and the surprisingly minimal neurological deficits associated with low-velocity midline spinal cord injuries.The patient had an excellent clinical outcome.The main lessons are that a wooden penetrating central nervous system injury has a high risk for infection,and that surgical removal from the spinal cord should be performed soon after injury and under direct visualization.
文摘Various crosslinking agents can be added to the formulations of natural-based adhesives for wood bonding in order to achieve better durability and higher strength of the formed joints.In the present study,the effect of hexamethylenediamine(HMDA)addition on the performance of liquefied wood(LW)adhesive for wood bonding is investigated.Differential scanning calorimetry showed the improved thermal stability and crosslinking of the LW adhesive with HMDA.The intensified presence of amide linkages(C–N bonds)was found in LW+HMDA with attenuated total reflection Fourier transform infrared spectroscopy.Analysis of the bonded joints using an automated bonding evaluation system showed that a higher press temperature resulted in stronger bonds for both types of adhesives.Moreover,the addition of HMDA to LW adhesive improved the bond strength of the joints and accelerated the crosslinking of the adhesive.However,with a tensile shear strength of(6.76±2.16)N×mm^(−2)(for LW)and(6.89±2.10)N×mm^(−2)(for LW+HMDA),both adhesives were found to be unsuitable for interior non-structural use.In addition,the acidity of LW resulted in relatively high wood failure(70%)in the adhesive joints tested.Improved crosslinking of LW with HMDA was reflected in improved resistance of LW+HMDA adhesive joints to water degradation.In conclusion,HMDA is a promising additive for improving the adhesive performance of LW adhesives.
基金funded by“Natural Science Foundation of Anhui Province,Grant No.2008085QC130”.
文摘This study aims to improve the value of fast-growing wood and extend the heat-treated wood utilization using inorganic calcium carbonate(CaCO_(3))crystals via an in-situ synthesis method.CaCl_(2)and Na 2CO_(3)solutions with a concentration ratio of 1:1 were successively introduced into the thermally modified poplar wood obtained by steam heat treatment(HT)at 200℃for 1.5 and 3 h,resulting in the in-situ synthesis of CaCO_(3)crystals inside the heat-treated wood.The filling effect was best at the concentration of 1.2 mol/L.CaCO_(3)was uniformly distributed in the cell cavities of the heat-treated wood,and some of the crystals were embedded in the fissures of the wood cell walls.The morphology of CaCO_(3)crystals was mainly spherical and rhombic polyhedral.Three main types of CaCO_(3)crystals were calcite,vaterite,and aragonite.The HT of poplar wood at 200℃resulted in degrading the chemical components of the wood cell wall.This degradation led to reduced wood mechanical properties,including the surface hardness(HD),modulus of rupture(MOR),and modulus of elasticity(MOE).After CaCO_(3)was in-situ synthesized in the heat-treated wood,the HD increased by 18.36%and 16.35%,and MOR increased by 14.64%and 8.89%,respectively.Because of the CaCO_(3)synthesization,the char residue of the 200℃heat-treated wood samples increased by 9.31%and the maximum weight loss rate decreased by 19.80%,indicating that the filling with CaCO_(3)cannot only improve the mechanical properties of the heat-treated wood but also effectively enhance its thermal stability.
基金financed by a Grant-in-Aid for Scientific Research from the Youth Program of National Natural Science Foundation of China(No.31800478)the National Natural Science Foundation of China(Grant Nos.31870535,32122058)。
文摘Drying crack is a common phenomenon occurring during moisture discharge from wood,reducing efficient wood utilization.Drying crack is primarily caused by drying stress,and the reasonable methods for determining drying stress are sparse.In this study,the initiation and propagation of cracks during wood discs drying were simulated using the extended finite element method(XFEM).The distribution of drying stress and displacement was analyzed at different crack conditions based on the simulation results.This study aimed to solve the problem of the limitation of drying stress testing methods and provide a new idea for the study of wood drying stress.The numerical simulation results are found in good agreement with the experimental results,thus corroborating the feasibility of XFEM in modeling drying crack of wood discs.The stress concentration was observed at the crack tip region,while a minor stress was presented in the region of crack passing through,indicating that the crack formation process was also a process of releasing drying stress.Further,more energy was required to form double cracks in comparison with the single crack mode.
基金financed under the scheme of Laboratory of Excellence ARBRE by the French Agence Nationale de la Recherche(ANR).
文摘This article presents the first applied results of using citric acid in combinations with a melamine-urea-formal-dehyde(MUF)resin for bonding wood veneers.The chemical reactions involved are shown based on a MALDI ToF analysis of the reaction of the MUF resin with citric acid.The preliminary results of the physical and mechanical properties of the LVL prepared are also presented.Veneers from Populus sp were used to manufacture 5-layer laminated veneer lumber(LVL)of small dimensions.Five combinations of the amount of citric acid,MUF spread rate and pressing parameters were tested.LVL bonded with 20%of citric acid+100 g/m^(2)of MUF,hot-pressed using a 3-step process with maximum 1.5 MPa of pressure yielded the board with better dimensional stability and mechanical properties.It could be concluded that citric acid in combination with MUF can be used for bonding wood veneer and the research should be continued to study further the parameters involved and to enhance the results.
