Analysing orthotropy in the core layer of wood based panels by means of fracture mechanics

In this study the orthotropic properties in the core layer of wood based panels are analyzed by means of the newly developed double cantilever I beam testing system. Four different wood based panels (i.e., OSB, particle board, particle board containing recycling chips and MDF) were tested in-plane, in longitudinal and lateral orientation. Specific fracture energy numbers yielded significant differences between the longitudinal and the lateral orientation for OSB, while the stress intensity factor analysis showed significant differences for OSB and particle board containing recycling particles.     

Untersuchungen an Holzwerkstoffen für Möbel-Einlegeböden

The bending deflection of six different wood based materials used as shelves in the manufacture of furniture (unlaminated particleboard, melamine laminated particleboard, veneered particleboard, block-board, plywood and solid wood panel) of approximately equal thickness was investigated. Deflection data were obtained by applying loads to the board surfaces for a period of 28 days followed by a period of unloading of equal length. For all types of particleboards the deflections appeared to be greater than for the other wood based panels. The lowest bending deflection was found for the solid wood panel while plywood performed better than blockboard. Surface treatments improved the performance of particleboards but veneering appeared to be more advantagous than laminating with melamine. The bending deflection of the tested panels is strongly related to their bending strength and modulus of elasticity.     

Measurement of emissions from air pollution sources. 3. C1-C29 organic compounds from fireplace combustion of wood

Organic compound emission rates for volatile organic compounds (VOC), gas-phase semivolatile organic compounds, and particle-phase organic compounds are measured from residential fireplace combustion of wood. Firewood from a conifer tree (pine) and from two deciduous trees (oak and eucalyptus) is burned to determine organic compound emissions profiles for each wood type including the distribution of the alkanes, alkenes, aromatics, polycyclic aromatic hydrocarbons (PAH), phenol and substituted phenols, guaiacol and substituted guaiacol, syringol and substituted syringols, carbonyls, alkanoic acids, resin acids, and levoglucosan. Levoglucosan is the major constituent in the fine particulate emissions from all three wood types, contributing 18-30% of the fine particulate organic compound emissions. Guaiacol (2-methoxyphenol), and guaiacols with additional substituents at position 4 on the molecule, and resin acids are emitted in significant quantities from pine wood combustion. Syringol (2,6-dimethoxyphenol) and syringols with additional substituents at position 4 on the molecule are emitted in large amounts from oak and eucalyptus firewood combustion, but these compounds are not detected in the emissions from pine wood combustion. Syringol and most of the substituted syringols are found to be semivolatile compounds that are present in both the gas and particle phases, but two substituted syringols that have not been previously quantified in wood smoke emissions, propionylsyringol and butyrylsyringol, are found exclusively in the particle phase and can be used to help trace hardwood smoke particles in the atmosphere. Benzene, ethene, and acetylene are often used as tracers for motor vehicle exhaust in the urban atmosphere. The contribution of wood smoke to the ambient concentrations of benzene, ethene, and acetylene could lead to an overestimate of the contribution of motor vehicle tailpipe exhaust to atmospheric VOC concentrations.     

Experimental determination of the compression resistance of differently shaped wood particles as influencing parameter on wood-reduced particleboard manufacturing

The price for industrial wood and, thus, particles for the manufacture of particleboard has been rising in the past and will be a topic of current interest in the future as economic growth is targeted at limited resources. One of the strategies to overcome this development is to reduce the amount of wood used for panel production. However, a simple reduction in the amount of wood used for panel manufacture leads to panels of lower density and, consequently, reduced properties. One approach to solving this problem is to re-engineer the particle mat structure to improve the panels’ density profile and, thus, meet required panel properties and at the same time lower board densities. As the particles’ compressibility is one of the main influencing parameters for density profile formation, it is the intention of this study to use a previously developed measurement method to give compression resistances of particles of various shapes and dimensions. It was found that the bulk density alone is not decisive for the particles’ compression resistance. The compression resistance derived from the change of particle shape is lower than that derived from wood substance compression. The compression resistance of large-sized particles was found to be higher than that of small-sized particles. It was concluded that a targeted combination of face and core layer particles improves the panels’ density profile.     

Shape- and dimensional stability of solid wood panels made from heat-treated lime wood strips

The paper presents the results of an experimental research performed with solid wood panels made from heat-treated and untreated lime wood (Tilia cordata Mill.) strips and then subjected to open-air exposure for 3 months. The dimensions of the panels were measured by means of an OPTODesQ Measurement Table, first after conditioning and sanding, then after each month of open-air exposure in order to assess their shape- and dimensional stability. After 3 months, the panels made from heat-treated wood strips showed up to 70% lower volumetric swelling and up to 143% lower flatness deviation than the panels made from untreated strips.     

Influence of utilization of?bagasse in surface layer on bending strength of three-layer particleboard

It is well known that wood species and particle size used influence the bending strength of three-layer particleboard. The objective of this study was to investigate the influence of using bagasse particles in surface layer on bending strength of three-layer particleboard panels. The ratio of the mixture of bagasse and wood particles was 3:7 and 4:6 in the surface and middle layers, respectively. Press temperatures were chosen at two levels of?165 and?180?°C. Three levels of urea formaldehyde resin were selected for the surface layers, namely: 8, 10, and 12?percent. Bending strength of the panels was determined according to the procedure of European Union (EN) Standard. The results show that bagasse has a positive effect on the bending strength of boards. In this research, the treatment with 40% bagasse and 12% resin in the surface layers and a?180?°C press temperature has resulted in an optimum bagasse board product.     

Improving the environmental profile of wood panels via co-production of ethanol and acetic acid

The oriented strand board (OSB) biorefinery is an emerging technology that could improve the building, transportation, and chemical sectors' environmental profiles. By adding a hot water extraction stage to conventional OSB panel manufacturing, hemicellulose polysaccharides can be extracted from wood strands and converted to renewably sourced ethanol and acetic acid. Replacing fossil-based gasoline and acetic acid has the potential to reduce greenhouse gas (GHG) emissions, among other possible impacts. At the same time, hemicellulose extraction could improve the environmental profile of OSB panels by reducing the level of volatile organic compounds (VOCs) emitted during manufacturing. In this study, the life cycle significance of such GHG, VOC, and other emission reductions was investigated. A process model was developed based on a mix of laboratory and industrial-level mass and energy flow data. Using these data a life cycle assessment (LCA) model was built. Sensitive process parameters were identified and used to develop a target production scenario for the OSB biorefinery. The findings suggest that the OSB biorefinery's deployment could substantially improve human and ecosystem health via reduction of select VOCs compared to conventionally produced OSB, gasoline, and acetic acid. Technological advancements are needed, however, to achieve desirable GHG reductions.     

Evaluation on some finishing properties of oil palm plywood

Oil palm is the largest and most important plantation crop in Malaysia. The oil palm generally lasts for 25–30 years before the next replantation is done. Substantial amount of biomass in the form of palm trunk results from plantation cycle. This resource is simply left on the ground to decay and is not used as raw material to manufacture any kind of value-added products. The objective of this study was to investigate the possibility of manufacturing plywood from oil palm trunks and to evaluate some of the finishing properties of such experimental panels in comparison to those from Shorea sp as control samples. Three-ply plywood samples were produced from 5 mm thick veneers of oil palm using urea formaldehyde adhesive. Three types of chemicals, namely nitrocellulose, pre-catalyzed lacquer and polyurethane were used to finish experimental panels. The surface finished with nitrocellulose had the lowest contact angle on raw surface of oil palm plywood and wood. The average cross cut tape index of oil palm plywood was comparable to Shorea sp. All finishing materials of oil palm plywood produced impact rating of 4 except for surface finished with nitrocellulose while finishing on wood indicated an impact rating of 3. Oil palm plywood had higher weight loss compared to Shorea sp. Based on results from contact angle, cross cut tape index, impact rate test, weathering, and soil burial test methods it appears that the samples showed acceptable finishing properties comparable to those of solid wood.     

Fate of Cu, Cr, and As during combustion of impregnated wood with and without peat additive

The E.U. Directive on incineration of waste regulates the harmful emissions of particles and twelve toxic elements, including copper, chromium, and arsenic. More information is critically needed on the speciation and behavior of these trace elements during combustion, including the effects of different process variables, as well as of different fuels and fuel mixtures. Using a 15 kW pellets-fueled grate burner, experiments were performed to determine the fate of copper, chromium, and arsenic during combustion of chromate copper arsenate (CCA) preservative wood. The effects of co-combustion of CCA-wood with peat were also studied since peat fuels previously have proved to generally reduce ash related problems. The fate and speciation of copper, chromium, and arsenic were determined from analysis of the flue gas particles and the bottom ash using SEM-EDS, XRD, XPS, and ICP-AES. In addition, chemical equilibrium model calculations were performed to interpret the experimental findings. The results revealed that about 5% copper, 15% chromium, and 60% arsenic were volatilized during combustion of pure CCA-wood, which is lower than predicted volatilization from the individual arsenic, chromium, and copper oxides. This is explained by the formation of more stable refractory complex oxide phases for which the stability trends and patterns are presented. When co-combusted with peat, an additional stabilization of these phases was obtained and thus a small but noteworthy decrease in volatilization of all three elements was observed. The major identified phases for all fuels were CuCrO2(s), (Fe, Mg, Cu)(Cr, Fe, Al)04(s), Cr2O3(s), and Ca3(AsO4)2(s). Arsenic was also identified in the fine particles as KH2AsO4(s) and As2O3(s). A strong indication of hexavalent chromium in the form of K2CrO4 or as a solid solution between K3Na(CrO4)2 and K3Na(SO4)2 was found in the fine particles. Good qualitative agreement was observed between experimental data and chemical equilibrium model calculations.     

Effect of radiata pine juvenile wood on the physical and mechanical properties of oriented strandboard

This work analyzes the impact of radiata pine (Pinus radiata D. Don) juvenile wood on the physical and mechanical properties of oriented strandboards (OSB). Radiata pine logs were obtained from 10 trees of a 26-year old managed stand located in the 8th Region of Chile. The experimental design considered the proportion of juvenile wood and strand orientation as independent variables. OSB panels of 0.4 m×0.4 m×12 mm were produced and tested. The results show that the juvenile wood proportion has a significant impact on the physical and mechanical properties of OSB. Strands orientation had a significant impact on all the properties studied with the exception of the modulus of elasticity in bending. However, this impact was small in all cases and would not change panel grade with the exception of linear expansion. In this case, panels made from tangential strands showed a higher linear expansion. According to these results, radiata pine juvenile wood can be used for the manufacturing of OSB up to a proportion of 70% of the oven-dry wood weight without significant losses of the physical and mechanical properties if the juvenile wood strands are located in the surface layers.     

Minimizing dust emission during routing operation of rubberwood

The study evaluated airborne dust emission (0.1–10 µm) during the routing operation of Rubberwood (Hevea brasiliensis) in the furniture industry in South East Asia. It was found that the average chip thickness of 0.1 mm and wood moisture content of 12–14% minimized dust emission, while the cutting tool rake angle had little influence on dust emission. The study shows that adverse economic implications due to health hazards posed by airborne dust emissions during wood machining can be reduced by manipulating the average chip thickness and work-piece moisture content.     

Investigation of physical and mechanical properties of oil palm wood core sandwich panels overlaid with a rubberwood veneer face

Low-density sandwich panels consisting of an oil palm wood core overlaid with a rubberwood veneer face were manufactured. Effects of two types of grain orientation of the oil palm wood core (parallel and perpendicular to board surface) and three different veneer thicknesses (0.7, 1.8 and 2.7 mm) and core densities (223 ± 14, 301 ± 35 and 418 ± 33 kg/m³) on some physical and mechanical properties of the boards were investigated. Results showed that higher core density increased the values of thermal conductivity, screw withdrawal resistance, modulus of rupture and modulus of elasticity but decreased the value of water absorption without effect on thickness swelling of the boards. Boards with the core grain direction oriented perpendicular to panel’s surface possessed lower value of thickness swelling but higher values of thermal conductivity and strain at fracture when the board failed in a mode of core shear under bending test than those of the others. Finally, the relationship between board density and the measured physical and mechanical properties of the oil palm wood core sandwich panels overlaid with a rubberwood veneer expressed as mathematical equations could be used to predict and design the expected properties of this type of sandwich board.     

Optimising the properties of OSB by a one-step heat pre-treatment process

Heat-treatment of solid wood to increase its dimensional stability and durability is well known and established in the industry. To enhance the application of wood-based panels (e.g. for exterior application) their durability against moisture and fungal decay has to be improved. In this paper a possibility is shown, how to adapt a heat treatment process on wood-based panels. Two different temperatures were applied on strands of Scots pine, before hot-pressing oriented strand board. The mechanical properties show an influence of the applied temperature on the strands and of the adhesive used for the panel. The thickness swelling is reduced (Fig. 3), resulting in increased dimensional stability. The process temperature has a major influence; with an increased pre-treatment temperature the thickness swelling is reduced. The internal bond strength was not affected by the pre-treatment.     

Minimizing dust emission during routing operation of rubberwood

The study evaluated airborne dust emission (0.1–10 μm) during the routing operation of Rubberwood (Hevea brasiliensis) in the furniture industry in South East Asia. It was found that the average chip thickness of 0.1 mm and wood moisture content of 12–14% minimized dust emission, while the cutting tool rake angle had little influence on dust emission. The study shows that adverse economic implications due to health hazards posed by airborne dust emissions during wood machining can be reduced by manipulating the average chip thickness and work-piece moisture content.     

Employing artificial neural networks for minimizing surface roughness and power consumption in abrasive machining of wood

One of the biggest challenges in machining processes of wood is to detect the optimum values of process parameters for reducing the final production cost. In the present study, the effects of various process parameters on surface roughness and power consumption in abrasive machining process of wood using experimental data collected from the literature were modeled by artificial neural networks (ANNs). The results have indicated that accurate prediction of the experimental data by neural network models was achieved with the mean absolute percentage error (MAPE) less than 2.51 % for power consumption and 2.65 % for surface roughness in the testing phase. Besides, the values of determination coefficient (R²) were found as 0.994 and 0.985 in the prediction of surface roughness and power consumption by the ANN modeling, respectively. Based on the results, it can be said that by means of the proposed models the surface roughness and power consumption can easily be predicted with very high degrees of accuracy in abrasive machining process of wood. Consequently, the present study can effectively be applied to the wood industry to reduce the time, energy consumption and high experimental costs because it eliminates the need for a large number of experiments.     

Mutagenicity of diesel engine exhaust is eliminated in the gas phase by an oxidation catalyst but only slightly reduced in the particle phase

Concerns about adverse health effects of diesel engine emissions prompted strong efforts to minimize this hazard, including exhaust treatment by diesel oxidation catalysts (DOC). The effectiveness of such measures is usually assessed by the analysis of the legally regulated exhaust components. In recent years additional analytical and toxicological tests were included in the test panel with the aim to fill possible analytical gaps, for example, mutagenic potency of polycyclic aromatic hydrocarbons (PAH) and their nitrated derivatives (nPAH). This investigation focuses on the effect of a DOC on health hazards from combustion of four different fuels: rapeseed methyl ester (RME), common mineral diesel fuel (DF), SHELL V-Power Diesel (V-Power), and ARAL Ultimate Diesel containing 5% RME (B5ULT). We applied the European Stationary Cycle (ESC) to a 6.4 L turbo-charged heavy load engine fulfilling the EURO III standard. The engine was operated with and without DOC. Besides regulated emissions we measured particle size and number distributions, determined the soluble and solid fractions of the particles and characterized the bacterial mutagenicity in the gas phase and the particles of the exhaust. The effectiveness of the DOC differed strongly in regard to the different exhaust constituents: Total hydrocarbons were reduced up to 90% and carbon monoxide up to 98%, whereas nitrogen oxides (NO(X)) remained almost unaffected. Total particle mass (TPM) was reduced by 50% with DOC in common petrol diesel fuel and by 30% in the other fuels. This effect was mainly due to a reduction of the soluble organic particle fraction. The DOC caused an increase of the water-soluble fraction in the exhaust of RME, V-Power, and B5ULT, as well as a pronounced increase of nitrate in all exhausts. A high proportion of ultrafine particles (10-30 nm) in RME exhaust could be ascribed to vaporizable particles. Mutagenicity of the exhaust was low compared to previous investigations. The DOC reduced mutagenic effects most effectively in the gas phase. Mutagenicity of particle extracts was less efficiently diminished. No significant differences of mutagenic effects were observed among the tested fuels. In conclusion, the benefits of the DOC concern regulated emissions except NO(X) as well as nonregulated emissions such as the mutagenicity of the exhaust. The reduction of mutagenicity was particularly observed in the condensates of the gas phase. This is probably due to better accessibility of gaseous mutagenic compounds during the passage of the DOC in contrast to the particle-bound mutagens. Concerning the particulate emissions DOC especially decreased ultrafine particles.     

The manufacture of particleboards using mixture of reed (surface?layer) and commercial species (middle layer)

This research was conducted to investigate the suitability of reed (Arundo donax) as a substitute for wood in laboratory made 3-layer particleboard in order to supplement the supply of raw material for the Iranian particleboard industries. The ratio of the mixture of reed and wood particles were 20:80, 30:70, and 40:60, respectively, in the surface and middle layers. Press temperatures were chosen at two levels of 165 and 185?°C. Three levels of urea formaldehyde resin were selected for the surface layers, namely: 8, 10, and 12 percent. The experimental panels were tested for their mechanical strength including modulus of elasticity (MOE), modulus of rupture (MOR), internal bonding (IB) and physical properties (thickness swelling and water absorption) according to the procedure in DIN 68763. In general, the results show that reed has a positive effect on the mechanical and physical properties of boards. In this research, the treatment with 40% reed, 12% resin in the surface layers and a 185?°C press temperature has resulted in an optimum reed board product.     

Particleboards production from date palm biomass

Date palm biomass is a renewable natural resource that has not widely been utilized in industry. The objective of this study was to examine some chemical properties of date palm trunk and rachis (holocellulose, cellulose, lignin and extractives) and to evaluate their suitability to produce composite panels. Particleboards were produced using trunk and rachis as an alternative raw material for forest products industry in the presence of two types of polycondensation resins (phenol–formaldehyde and melamine urea–formaldehyde) which were selected as binding agents. The panels were tested for their physical (water absorption and thickness swelling) and mechanical (modulus of rupture, modulus of elasticity and internal bond strength) properties. The internal bond strength of date palm trunk and date palm rachis based boards met the requirements of the general purpose product standards (EN 312) at 0.70 g/cm³ density. The panels made with phenol–formaldehyde resin showed better performance with respect to the panels made with melamine urea–formaldehyde. In addition, the particleboard made with date palm trunk particles had better quality compared to the particleboard made from date palm rachis particles. Based on preliminary results of this work, raw materials from date palm trunks and rachis can have a promising potential in the manufacture of particleboards and as a substitute for wood in board production.     

Untersuchungen zum Einfluss des Plattenaufbaus auf ausgewählte Eigenschaften von Massivholzplatten

The coefficient of thermal conductivity, the equilibrium moisture content, the in-plane swelling and the water vapour resistance of laboratory-produced three-layer solid wood panels of Norway spruce wood were tested. The coefficient of thermal conductivity is in the range of 0.09–0.11 W/m·K in normal climate. The voids in the middle layer (slots, spaces between the lamellas) cause a slight decrease of the coefficient of thermal conductivity. The orientation of the growth rings has an effect on the thermal conductivity as well. The water vapour resistance is affected by the orientation of the growth rings in the layers and the voids in the middle layer. The equilibrium moisture content above a relative humidity of 35% is slightly below the one of solid spruce wood. The equilibrium moisture content of solid wood panels with a middle layer of wood-based material is smaller because of its lower equilibrium moisture content compared with solid wood.     

Emission of polycyclic aromatic hydrocarbons, toxicity, and mutagenicity from domestic cooking using sawdust briquettes, wood, and kerosene

Smoke samples, in both gas and particulate matter (PM) phases, of the three domestic stoves were collected using U.S. EPA modified method 5 and were analyzed for 17 PAH (HPLC-UV), acute toxicity (Microtox test), and mutagenicity (Amestest). The gas phase of smoke contributed > or = 95% of 17 PAH, > or = 96% of toxicity, and > or = 60% of mutagenicity. The highest emission factor of 17 PAH was from sawdust briquettes (260 mg/kg), but the highest emission of 11 genotoxic PAH was from kerosene (28 mg/kg). PM samples of kerosene smoke were not toxic. The total toxicity emission factor was the highest from sawdust, followed by kerosene and wood fuel. Smoke samples from the kerosene stove were not mutagenic. TA98 indicated the presence of both direct and indirect mutagenic activities in PM samples of sawdust and wood fuel but only direct mutagenic activities in the gas phase. TA100 detected only direct mutagenic activities in both PM and gas-phase samples. The higher mutagenicity emission factor was from wood fuel, 12 x 10(6) revertants/kg (TA100-S9) and 3.5 x 10(6) (TA98-S9), and lower from sawdust, 2.9 x 10(6) (TA100-S9) and 2.8 x 10(6) (TA98-S9). The low burning rate and high efficiency of a kerosene stove have resulted in the lowest PAH, toxicity, and mutagenicity emissions from daily cooking activities. The bioassays produced toxicity and mutagenicity results in correspondence with the PAH content of samples. The tests could be used for a quick assessment of potential health risks.