Wood and Fiber Science (E-Journal)
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NEW PROTOCOL FOR SPECIES MIX TESTING IN RETAIL MULCH SAMPLES
No full textMany millions of bags of mulch are sold at retail in the United States each year. Most mulch products claim to be of a certain species, with cypress being perhaps the most widely marketed. Unfortunately, it is practically impossible for the average consumer to know with certainty whether a product is indeed the species listed on the packaging. Claims of misleading behavior by some producers raise the question of whether species mix should be more closely monitored. Regulators charged with ensuring fair competition and consumer welfare, however, do not have an accurate means to determine species content. It would be difficult, if not impossible, to determine the species mix for 100% of the wood particles in a package of mulch because of the inability to identify species of the smallest particles, and the impracticality of 100% sampling in the intended use. We propose and develop a new method to allow analysts to estimate the percentage of a given species in samples of mulch, with a focus on cypress. This case study illustrates our methods and highlights the challenges in accurately determining species mix in the type of wood product. We purchased and tested 10 bags of cypress mulch obtained from six different states. Results indicate that one producer was filling some bags with only 50% cypress and others with no cypress. Consumers may therefore suffer as they receive a lower valued species, whereas honest competitors are also harmed. The wood science community could help regulators and consumers by developing a method by which small particles of wood could be positively identified as to species. Improved methods for species identification are relevant for a wide variety of purposes ranging from identifying consumer products to upholding the U.S. Lacey Act.
Effect of Wood Species on the Pore Volume and Surface Area of Activated Carbon Derived From the Self Activation Process
Full text linkIn this study, the effect of wood species on pore structure of activated carbon (AC) generated from a self-activation process at different dwelling times was investigated. Ten hardwood species were selected (afromosia, alder, black cherry, makore, pomelle sapele, soft maple, teak, walnut, white oak and yellow poplar) were activated at 1050OC for three dwelling times (10 h, 5 h, and 2.5 h). X-ray diffraction, Raman spectroscopy, and elemental analysis were performed on AC to analyze the carbon structure. The Brunauer-Emmett-Teller (BET) surface area, Barrett-Joyner-Halenda (BJH) pore volume, and BJH pore width of AC samples were determined. It was shown from the study that the mesopore width of AC decreased as micropores were transitioned to mesopores, leading to an increase in the pore volume and surface area. The density and porosity of the samples that underwent 2.5-h dwelling time were determined. The porosity of the wood and their resultant AC were compared. The porosity between the wood and its AC possessed a relationship when true bulk densities of the wood and carbon were compared. The porosity of wood had an impact on the bulk density of the carbon but not on the true density. No relationship was observed between the porosity and surface area of the carbon samples.
EVALUATION OF DELAMINATION AND BENDING PERFORMANCE OF COMPOSITE CLT REINFORCED WITH CFRP
Full text linkTo develop a high-performance, lightweight cross-laminated timber (CLT) floor, this study tested the delamination performance between carbon fiber-reinforced plastic (CFRP) and CLT and the bending performance of a CFRP composite CLT that was differently reinforced according to the shape of CFRP. The test results showed that the soaking and boiling delamination between CLT and CFRP of the CFRP composite CLT produced by spreading a polyurethane (PUR) adhesive at 300g/m2 were both less than 5%, satisfying the Korean standard. Furthermore, the composite CLT (3ply) of which the entire outer surface of the tension laminae was reinforced with a CFRP plate (thickness: 1.2 mm) showed a mean MOE and a mean MOR higher by 27% and 48%, respectively, than those of the unreinforced CLT (3ply). Furthermore, even though the weight of this CFRP composite CLT was smaller than that of 5ply CLT by approximately 40%, its bending moment was measured higher by 14% than that of the 5ply CLT (thickness: 175 mm) fabricated by limited state design (LSD) as specified in PRG-320
EFFECTS OF RADIAL GROWTH RATE ON WOOD AND LUMBER ROPERTIES OF 67-YEAR-OLD JAPANESE LARCH (LARIX KAEMPFERI) TREES PLANTED IN TOCHIGI, JAPAN
Full text linkThe wood and lumber properties were examined for 67-yr-old Japanese larch (Larix kaempferi) trees with different radial growth rates planted in Tochigi Prefecture, Japan. The trees were categorized into slow-, medium-, and fast-growing groups based on the stem diameter. No significant difference in stresswave velocity of stems, which is closely related with Young’s modulus of wood, was found among three radial growth categories (stem diameter classes). The boundary between juvenile wood (JW) and mature wood (MW) determined by latewood tracheid length (TL) existed about the 20th annual ring from the pith in all sample trees. Significant differences between JW and MW were found in most of examined wood and lumber properties. It was found that trees with fast growth do not always cause lower grade lumberproperties.
Physical and Chemical Characterization of Chinese Fallen Poplar Leaf Ash: Effects of the Calcining Temperature and Aqueous Solution
Full text linkThis study focused on the physical and chemical characterization of Chinese poplar leaf ash (PLA) with 500, 700 and 850 °C calcination temperatures and residual PLA leaching from aqueous solution. The grain size distribution, chemical composition and microstructure of PLA were investigated by the laser granulometric distribution, X-ray fluorescence (XRF) and scanning electron microscopy (SEM). The ash samples obtained before and after aqueous dissolution were analyzed using X-ray powder diffraction (XRD) to identify the mineral components. X-ray photoelectron spectroscopy (XPS) was used to illustrate the Si 2p and Al 2p transformation behaviors in the PLA samples. The zeta potentials, conductivities and pH values of hybrid-solutions were tested at different dissolution times. Silica, sulfur, calcium and potassium were the dominant components observed in the PLA. The conductivities and pH values were nearly stable with an increasing dissolution time. The zeta potential of PLA was calculated to be a negative value. Calcite and potassium sulfate were found in the PLA-500 and PLA-700 samples, whereas magnesite and lime were easily identified in PLA-850. The Si 2p peak shifted a lower position because of the additional synthesis of Si-OH with the increasing calcination temperature. These conclusions could help investigations into the possibility of using PLA in cement systems.
Comparison of Evaluation Results of Nailed Joints in Shear Properties Obtained from Two Methods
Full text linkShear properties of nailed joints must be evaluated to understand the mechanical property of structural elements using nailed joints. Numerous studies regarding this evaluation exist. However, the testing methods differ between the studies. Thus, clarification of the difference in the evaluated results of the testing methods becomes important. Therefore, this study aims to clarify this difference by conducting shear tests on nailed-joint specimens. This study adopts two methods, which are described in ASTM International and Japanese Agricultural Standard, respectively. The evaluated results of the tests are compared. The comparison clarifies that there is no difference in the average values of the characteristics. Meanwhile, a difference is observed in the variance. In addition, this study discusses the reasons for this difference. The author posits a hypothesis that the difference in variance is due to the difference in the number of nails in the joint specimens and presents the validity of this hypothesis with an analysis using the Monte-Carlo method
Effects of size, species and adjacent lamina on moisture related strain in glulam
Full text linkThe goal of this study was to investigate the effects of size and species on moisture-related strain in glued–laminated timber (glulam). Swelling and shrinkage behaviors of different sizes (120 120, 180 180, and 180 240 mm2) of glulam made from larch and pine were measured using digital image correlation. A new approach to predict dimensional changes of glulam was developed by reflecting the nonlinear behavior of shrinkage based on MC change. It was compared with the existing method provided by the American Wood Council (AWC). Moisture-related strains of glulam were significantly influenced by size and species. Coefficients of swelling or shrinkage of glulam were determined to indicate statistical significance. When MC was changed from saturated condition to EMC of 12%, differences in dimensional changes in the width direction between experimental test and prediction results using the AWC method ranged from 87.7% to 260.0%. However, differences in dimensional changes in the width direction between experimental test and prediction results using the newly developed method ranged from 1.8% to 15.9%. Strains in the width direction of glulam could be affected by adjacent laminas along the glue line and the new approach could account for the effects. However, the AWC method could not reflect the effects of adjacent laminas along the glue line. Therefore, better prediction accuracy was achieved by using the new approach
Potential of Natural-Origin Loblolly Pine Tree Fractions as A Bioenergy Feedstock
Full text linkChemical characterization was performed on ten different samples of loblolly pine (Pinus taeda L.), representing various woody components of trees (bole, slab, tops and branches, and whole tree) harvested from two naturally regenerated forests in southern Arkansas (USA). Ultimate analysis, proximate analysis using thermogravimetry, and the energy content of the samples were determined to help evaluate their bioenergy utility. These whole tree samples may be an attractive prospect for bioenergy applications such as gasification, pelletization, and combustion, owing to favorable heating content values and relatively low ash content. Although a number of logistical challenges exist in their acquisition and processing, slabs, topwood, and branches offer opportunities for bioenergy applications that can increase the utilization of forest residues without threatening more traditional uses of wood in lumber, panels, and paper. Finally, we then briefly consider the silvicultural implications of these results for naturally regenerated southern pine-dominated forests
Optimization of Performance of Bamboo Mat Corrugated Sheets Using Response Surface Methodology
Full text linkIn this study, a bamboo composite with a corrugated structure, bamboo mat corrugated sheets (BMCS), was manufactured. As subset of the response surface methodology, Box–Behnken design was used for designing experiments, statistically modeling the processing conditions–properties relationships, and for identification of the potentially optimum conditions for BMCS. Three variables (MC, pressing temperature, and pressing time) at three levels were studied. Results showed that all the tested properties (deformation ratio, failing load, bending strength, and impact strength) were best described by quadratic regression models. Keeping MC at higher level significantly decreased the deformation ratio. All the three factors and interactions between any two of them were significant model terms for failing load. Pressing temperature, pressing time, and their interactions were significant model terms for bending strength. The interaction effect of MC and the other two factors was significant for impact strength. The best optimized conditions were determined using a desirability function approach to be MC 12.3%, pressing temperature 146.2°C, and pressing time 12.8 min that optimized 1.8% for deformation ratio, 542 N for failing load, 185.7 MPa for bending strength, and 36.5 kJ/m2 for impact strength of BMCS.