Treesearch

The anisotropy of wood creates a complex problem for solving heat and mass transfer problems that require analyses be based on fundamental material properties of the wood structure. Inputting basic orthogonal properties of the wood material alone are not sufficient for accurate modeling because wood is a combination of porous fiber cells that are aligned and mis-aligned in low- and high-density regions called annual rings. Modeling heat transfer requires the development of effective thermal conductivities as a function of those parameters associated with the rings. Effective 2D thermal...

A fiber model and simulation method are employed to investigate the mechanical response of planar fiber networks subjected to elongational deformation. The simulated responses agree qualitatively with numerous experimental observations. suggesting that such simulation methods may be useful for probing the relationships between fiber properties and interactions and the behavior of fiber networks. Quantitative discrepancies between experiments and simulations are attributed in pan to computational limitations, in addition to potential shortcomings in the underlying fiber model.

In order to circumvent the problem of altering the sheet composition to increase bonding, in this study the bonding was increased by wet pressing and press drying sheets to various levels of RBA. The operating regime problem was then studied by interpreting the tear relative to bonding (where bonding is measured as T/Z, Tensile index/Zero span tensile index) relationship in whole TMP, its fractions and mixtures of these fractions. In addition the effect of fiber length on the tear strength at various bonding levels was studied using the data obtained from the mixture studies.

Excessive variability in the final moisture content (MC) of hardwood lumber may have a significant impact on secondary wood processing and final product performance. Sources of final MC variation during kiln- drying have been studied in prior research. A test examining the final MC of red oak (Quercus spp.) and yellow-poplar (Liriodendron tulipifera) lumber after kiln-drying was conducted to obtain empirical knowledge of the effects from anatomical structures and lumber thickness A 23 fixed- effects linear statistical model was used to examine MC changes and the effects that growth rate....

The purpose of this study was to investigate mechanical and physical performances of particleboard made from low-value eastern redcedar trees. The properties evaluated included bending strength and stiffness, swelling, surface hardness, and screw holding capacity as a function of processing variables (i.e., density, chip type, and board construction). Two types of chips (whole tree and pure wood), two types of mat constructions (single- and three-layer), and four different density levels (0.4, 0.5, 0.65, and 0.75 g/cm3) were used in manufacturing the test panels. Board density and mat...

Wood-plastic lumber is promoted as a low maintenance high-durability product. When exposed to accelerated weathering, however, wood-plastic composites may experience a color change and/or loss in mechanical properties. Different methods of manufacturing wood-plastic composites lead to different surface characteristics, which can influence weathering, In this study, 50% wood-flour filled high-density polyethylene (HDPE) composite samples were injection molded, extruded, or extruded and then planed, to remove the manufacturing surface characteristics. Fourier transform infrared spectroscopy...

Wood-plastic composite decking has made major advances in material performance, processing and user acceptance. The growth of wood-plastic composite decking in North America has grown from less than 1 % in mid- 0's to over 10% today with growth projected by several studies to reach +20% before the end of this decade (2010). Preservative-treated wood decking experienced a very similar market entry and growth to market dominance over the 1970's and 80's in this same outdoor decking market when treated-wood supplanted naturally-durable redwood and cedar decking materials. Now that wood-plastic...

The effect of lignin-biopolymer structure on the mechanism of its oxidative depolymerization by polyoxometalates (POMs) was investigated by reacting an equilibrated POM ensemble with a series of ring-substituted benzyl alcohols. Under anaerobic conditions in mixed water/methanol, observed pseudo-first order reaction rates (150°C) of 8.96 x 10–3 and 4.89 x 10–3 sec–1 were obtained for oxidations of 1-(3,4-dimethoxyphenyl) ethanol (1) and 1-(3,4,5-trimethoxyphenyl)ethanol (2), respectively. Organic products from the oxidation of 2 (95% recovery) indicate the reaction proceeds via successive...

In most developing countries wood and charcoal are the predominant fuels for preparation of food to maintain the quality of life that encompasses the majority of citizens. In many developing countries wood fuels are also important for small and medium size industries. Moreover, energy from wood continues to be important in industrial countries. In the USA biomass including waste wood and alcohol from corn provided about 3.3% of total energy consumption in 2000. This was more than was provided by conventional hydroelectric power and more than other forms of renewable energy. Wood energy is...

Innovation in advancing technoogies for production of pulp and paper has been driven, by and large, by the needs to reduce the environmental impact of pulp mills or to enhance the yield in processes of conversion of wood to fibers. "Fiberization" of wood chips is carred out in two categores of processes. One, chemical pulping relies on removing the lignin that binds the cellulose fibers together by chemical delignification processes. The other is based on mechanical fiberization of the wood while retaining much of the lignin. The resulting pulps have significantly different properties. The...