Wood and Fiber Science (E-Journal)
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THERMAL MODIFIED TIMBER (TMT): RECENT DEVELOPMENT IN EUROPE AND NORTH AMERICA
Get PDFThe world’s political and economic decisions are increasingly determined by resource and energy scarcity and by climate change. In these circumstances, a balance must be achieved between economics, ecology and social welfare, which was put forward at the end of the 20th century and has been irrevocably linked to forestry ever since. It is essential that the forest sector is placed at the centre of the developing bio-based economy. The value of the forest for mankind and the environment is irrefutable, and the value of the multitude of products made of wood is of great importance, socially, economically and environmentally. Over the last fifty years, sawn timber in particular has largely disappeared from many technological applications diminishing its contribution to sustainability in the one area where it could be most significant: as a substitute for energy-intensive materials (e.g., in the built environment). However, there is currently a resurgence of interest in timber products due to the environmental benefits they provide, a phenomenon that other industrial sectors are well aware of. This paper discusses the role of thermal wood processing in a sustainability of resource utilization context and what thermal wood processing should achieve to contribute to the European low-carbon economy
THERMAL INSULATION PERFORMANCE ASSESSMENT OF AGGLOMERATED CORK BOARDS
Get PDFOver the last few years, the building industry has been focusing on research, on the construction of passive houses and on the use of natural, local materials that are non-toxic, recyclable and can assure high thermal insulation. Cork is a natural material whose qualities have been known since ancient times and which fully meets sustainability requirements. High quality cork is mainly used to produce bottle stoppers. Owing to the manufacturing process, over 75% of it becomes a waste product. Furthermore, a large amount of waste cork comes from industry, from forest cleaning and pruning and from waste selection. Such a material is then recycled and triturated to obtain cork granulate. Cork granulate is a sustainable solution that recycles a waste product, which substantially keeps the characteristics of the original material, and turns it into a resource for manufacturing new products, such as insulating boards made up of cork agglomerate that are increasingly used in the building sector. In this paper, certain thermophysical parameters of six agglomerated cork boards are evaluated. Different constituent characteristics of the boards, such as grain size distribution, density and thickness, were taken into account in order to evaluate how they may influence insulating performances. The tested agglomerated cork boards showed thermophysical characteristics similar to those of the cork bark and even highlighted a higher diffusivity value than natural cork. Ultimately, it may be assumed that the agglomerated cork boards are a suitable and sustainable solution particularly for the thermal insulation of buildings in hot climate areas and where a healthy environment is required
Lateral connection behavior of molded core sandwich panels with self-tapping screws
Get PDFThis study investigated lateral connection behavior of a single shear connection between a molded core sandwich panel produced with wood strands, and solid sawn lumber. A continuous thread self-tapping screw and common nail were the fasteners evaluated. Connection assemblies with self-tapping screws showed much greater stiffness, yield load, and load-carrying capacity than nailed assemblies, indicating that self-tapping screws may be a viable option for connections between wood-based molded core panels and solid sawn lumber
IN-PLANE BENDING MOMENT RESISTANCE OF T-SHAPED ONE-SIDED TWO-GUSSET-PLATE FURNITURE JOINTS IN ORIENTED STRANDBOARD
Get PDFThis study investigated the in-plane bending moment resistance of a T-shaped joint connected with two gusset plates stapled on one side of joint members in three oriented strandboard (OSB) materials. Experimental results indicated that in-plane moment resistance loads of T-shaped, one-sided, two-gusset-plate joints at ultimate point on average were about 1.9 times their corresponding moment loads at proportional limit. The proposed mechanical model was verified experimentally as a valid means for deriving estimation equations of in-plane bending moment resistance loads of T-shaped, one-sided, two-gusset-plate joints in OSB materials used in the study. Experimental results and derived equations of in-plane bending moment resistance loads indicated that a T-shaped, one-sided, two-gusset-plate joint in OSB materials will always have a higher in-plane bending moment resistance load than an L-shaped one if the rail width in a L-shaped joint is the same as the stump width in a T-shaped joint. The difference in magnitude is affected by the critical joint member width and distance from the point at the stump where the external in-plane moment load is applied to the rail top edge
RELEASE CHARACTERISTICS AND EFFECTS ON EUCALYPTUS TREE GROWTH OF FERTILIZER FROM WOOD RESIDUE SLOW-RELEASE FERTILIZER SHELL
Get PDFTo investigate the release characteristics and effects on tree growth of fertilizer from woodresidue slow-release fertilizer shells, fertilizer was loaded into the wood residue shells and the resultantslow-release fertilizers were evaluated using eucalyptus fertilization tests. The growth parameters (girth,height, and standing volume) and nutrient contents of soil and tree leaves were monitored regularly toevaluate the effects of wood residue slow-release fertilizer shells on tree growth and to determine theprocess by which fertilizer was released. Fertilizer-loaded Pinus massoniana and Toona sinensis shellsand straight fertilizer can all significantly improve growth, eg girth at breast height, height, and standingvolume. The K, N, and P contents in soil and tree leaves were not significantly different among groupstreated with P. massoniana and T. sinensis residue shell slow-release fertilizer and straight fertilizer,which suggests that these three fertilizers did not differ with respect to effects on soil nutrients and leafnutrients. Wood residue shell slow-release fertilizer can significantly increase tree growth, includinggrowth in girth, height, and standing volume. These shells provide satisfactory fertilizer release dynamics.Toona sinensis shells provided better slow-release properties than did P. massoniana shells.Keywords: Forest fertilization test, nutrients, tree growth, wood residue shell slow-release fertilizer
ISOLATION AND CHARACTERIZATION OF MICROCRYSTALLINE CELLULOSE FROM OIL PALM FRONDS USING CHEMO-MECHANICAL PROCESS
Get PDFThis study investigates the characteristic of the microcrystalline cellulose (MCC) isolated from oil palm (Elaies guineensis) fronds using acid hydrolysis method. The morphology and size of the MCC were characterized using both Sherrer equations for X-ray diffraction (XRD) result and transmission electron microscopy (TEM). The thermal stability of MCC was determined from thermogravimetry analysis (TGA) profiles whilst, Fourier transform infrared spectroscopy (FTIR) was used to analyse the chemical modifications that occurred under these conditions. The XRD results showed that the MCC isolated from oil palm fronds (OPF-MCC) fibres had an average diameter and crystallinity index of 12.15 nm and 60.1 % respectively. Both the FTIR and the XRD indicated that lignin and hemicellulose contents decreased while the cellulose-I polymorph remained constant. Thermogravimetric analysis (TGA) revealed that OPF-MCC had higher thermal stability compared to the OPF fibres. The study revealed the potential applications of the MCC isolated from the oil palm biomass as green reinforcement or/and fillers in the production of biodegradable biocomposite
ASSESSMENT OF A THREE DIMENSIONAL FIBRE ORIENTATION MODEL FOR TIMBER
Get PDFWood is an orthotropic material with very different properties along and across fibres, and every board has its own pattern of knots and fibre deviations. Therefore, detailed knowledge of the three dimensional fibre orientation of individual boards would enable more accurate assessment of properties like stiffness, strength and shape stability. This paper presents a method for modelling 3D fibre orientation of side boards of Norway spruce. The method is based on dot laser scanning and utilization of the tracheid effect, and it is verified by a comparison between strain fields calculated on the basis of the fibre orientation model and corresponding strains determined using digital image correlation (DIC) technique. By means of the method, it is possible to identify knots and to reproduce the fibre orientation in clear wood in the vicinity of knots. Fibre orientation models of side boards including traversing edge knots were established and integrated in finite element board models used for simulation of four point bending tests. The same boards were also tested in laboratory and displacement fields of the wide faces were recorded at different load levels using DIC technique. Comparisons of strain fields from measurements and simulations showed close agreement, regarding both strain patterns and strain levels. Local strain concentrations caused by very small defects were detected using the models and also found from the laboratory test results. The modelling approach is promising and may be developed further for more advanced assessment of e.g. crack propagation and strength properties in both side boards and centre cuts
LOAD-DEFLECTION BEHAVIOR OF RATTAN CHAIR SEATS
Get PDFThe static and fatigue performances of seat foundations of natural rattan chairs subjected to vertical loads were investigated. Static performance evaluation results indicate that rattan strip weaving patterns have significant effects on the vertical load carrying capacity and stiffness performance of chair seat foundations. Herringbone and grid pattern woven seat foundations had significantly higher vertical load carrying capacity than those made with a square-corner pattern. Square-corner pattern seat foundations yielded a softer sitting surface than herringbone and grid patterns. Herringbone and grid pattern seat foundations can provide firmer sitting feel and good deep down support for heavier sitters. The Burger model could be used to describe the force-deformation-time behavior of a rattan woven seat foundation subjected to vertical cyclic loading
HYDROGEN BONDING IN WOOD-BASED MATERIALS: AN UPDATE
Get PDFThe contribution of hydrogen bonding to wood science and technology has been well recognized over the past century. The hydrogen bond is an important chemical characteristic contributing to wood-based material behavior and it also provides an important contribution to processing features of wood. However, the current understanding of hydrogen bond strength as a contributor to wood-based material behavior has not been updated in the wood literature. Wood-based material literature typically report hydrogen bond strengths ranging from 12.6 to 25.2 kJ/mol (3 to 6 kcal/mol) while newer data from the general chemistry field report hydrogen bond strengths up to 189 kJ/mol (45 kcal/mol), which are characteristic of covalent bond strength. In light of these new data regarding hydrogen bond strengths, it provides impetus to discuss the new understanding of hydrogen bond strength relative to wood-based material behavior. Recent developments in nanotechnology of renewable materials leading to the production and applications of cellulose nanomaterials with much higher surface areas and hydrogen bonding capacity also mandate revisiting our knowledge of the hydrogen bonding mechanism and strength
DEGRADATION OF YIELD STRENGTH OF LATERALLY LOADED WOOD-TO-ORIENTED STRANDBOARD CONNECTIONS AFTER EXPOSURE TO ELEVATED TEMPERATURES
Get PDFWood to sheathing connections is crucial to lateral force resisting system of the wood-frame structure. Engineers are often faced with the challenge of predicting strength of a partially damaged structure after it has been exposed to elevated temperature during a fire. Numerical simulations to predict the residual strength need thermal degradation data and models for the material as well as the connections. Therefore, it is important to categorize connection response when exposed to elevated temperatures for a sustained period of time. This study addresses this issue by developing models to predict lateral yield strength degradation of wood to Oriented Strandboard (OSB) connection after exposure to elevated temperature. A total of 394 Douglas-fir to OSB connections were tested laterally as a function of 8 different temperatures and 8 exposure times within each temperature regime. Yield strength of the connection decreased as a function of temperature and exposure time. Rate of degradation was higher at higher temperatures. A regression-based statistical model was developed. Additionally, these results were fit to a 2-step simple kinetics model, based on the assumption of degradation kinetics following an Arrhenius activation energy model. The kinetics-based model was preferred over regression model as it fit the data better with one less parameter and predictions consistently matched the observed values for an independent data set