Wood and Fiber Science (E-Journal)
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Water State Study of Wood Structure of Four Hardwoods Below Fiber Saturation Point with Nuclear Magnetic Resonance
Get PDFNuclear magnetic resonance (NMR) is a useful, powerful, and noninvasive technique to study the dynamics of wood-water relations, both quantitatively and qualitatively. The main objective of this study was to use NMR to characterize the state of water below the FSP. Two tropical hardwood species, huayruro (Robinia coccinea Aublet) and cachimbo (Cariniana domesticata [C. Martius] Miers), a plantation-grown eucalyptus species (Eucalyptus saligna Smith), and a temperate species, red oak (Quercus rubra L.), were studied. These species were chosen for their diversity in terms of anatomical and physical properties. Desorption tests were carried out at 21°C in a single-step procedure from full saturation state for huayruro, cachimbo, and red oak and from green condition for E. saligna. Discrete T2 times were obtained for each species and equilibrium moisture content (EMC). The results showed that even under EMC, there was a region in the hygroscopic range in which the loss of bound water takes place before all liquid water was drained. This region varies according to wood species. Furthermore, variation in the fast T2 values among the different wood species gives an indication of how bound water is distributed and arranged in sorption sites
Book Review: Natural Fiber Composites: Materials, Processes and Properties, edited by Alma Hodzic and Robert Shanks
No full textMeasurement of Rolling Shear Modulus and Strength of Cross-Laminated Timber Using Bending and Two-Plate Shear Tests
No full textRolling shear properties of cross-laminated timber (CLT) are very low because of the configuration of the cross layer. In some applications, they are the key properties that govern the design and application of CLT. To explore an appropriate method for assessing the rolling shear properties of CLT, variable span bending tests and two-plate shear tests were conducted. Three types of down-scaled black spruce (Picea mariana) specimens, including wooden cross layer (WCL), steel-wood-steel (SWS), and three-layer down-scaled CLT (wood-wood-wood [WWW]), were fabricated using one-component polyurethane (for edge gluing) and epoxy adhesive (for steel and wood bonding). Deflection of a WWW specimen was predicted using a shear analogy method based on rolling shear modulus (Grt) of the cross layer obtained from the variable span bending test and two-plate shear test methods and was then compared with the deflection directly measured on WWW specimens. The test results showed that rolling shear modulus of WCL from the two-plate shear test was 72.61 MPa, which was more than twice that of the cross layer of SWS from the variable span bending test. Rolling shear strength of WWW measured using the three-point bending method was 2.74 MPa at a span-to-depth ratio of 6
Characterization of Major Components in Barks from Five Canadian Tree Species
Get PDFIn this study, the major components in barks from five Canadian tree species and their chemical and biological properties were characterized. The extractives soluble in hexane, ethanol, and 1% NaOH solution were measured through successive extractions. Total phenolic content was determined by the Folin-Ciocalteu method, antioxidant activity was evaluated by 1,1-diphenyl-2-picrylhydrazyl-free radical scavenging assay, and the characteristics of functional groups were analyzed by Fourier transform IR spectroscopy. The formaldehyde-condensable polyphenols were estimated with the Stiasny method. Lignin and holocellulose contents were determined by gravimetric method. Results showed that the amounts of extractives soluble in the three solvents varied significantly with bark species. Lodgepole pine bark contained the highest content of hexane-soluble extractives (15.0%), and aspen bark contained a very high content of ethanol solubles (22.3%). The 1% NaOH solubles ranged from 20.5 to 35.5% of the original bark. Except balsam fir, the total phenolic contents of ethanol solubles were between 200 and 300 mg equivalent catechin per gram of extract. The ethanol-soluble extractives from lodgepole pine bark and sugar maple bark had considerably high antioxidant potential; their IC50 values were about 11 μg/mL. The barks of softwood species contained a higher amount of formaldehyde-condensable polyphenols than those of hardwood species included in this study
Investigation of Wood Impact Properties Using Fractal Dimension Analysis
Get PDFFractal analysis is a research tool recently used to model various processes. However, this analysis has not been used for determining impact properties of wood. In this study, the transverse and longitudinal impact ductility of five species, ie white pine, poplar, pine, birch, and basswood, was experimentally determined. Based on the grid-cover method, photographs were taken of the fracture surfaces and edited by image graying using Photoshop CS5 (Adobe Systems Inc.). The yardstick δ was determined by adjusting the distance between the grid lines. The slope K of the regression equation of Log(1/δi) vs Log(N[δi]) was the fractal dimension DL of the fracture profile curve. Fractal dimension allows us to measure the complexity of fracture profiles after the specimens were broken by impacts. The results indicate that the average fractal dimension values were 2.023-2.075 on the fractures from transverse and longitudinal impacts. The longitudinal impact ductility was greater than the transverse for all tested species. The transverse and longitudinal impact ductility was linearly related to the fracture fractal dimension
Variations in Pore Structure of Activated Carbon Fibers from Liquefied Wood with Preoxidation Treatment
Get PDFPreoxidation treatments in air at 200-280°C were introduced in the preparation of activated carbon fiber from liquefied wood (LWACF) with steam activation at 910°C to enlarge its pore size distribution (PSD). LWACF yield was improved 1.14 times with preoxidation at 200°C. With increasing preoxidation temperature, the specific surface area increased from 2592 to 3068 m2/g. Preoxidations at 200 and 240°C predominantly enhanced the microporosity development without significant pore widening, whereas preoxidation at 280°C significantly enlarged the PSD. Mesopore volume increased by 72%, and methylene blue adsorption capacity improved by 34%
Formation of Nanocarbon Spheres by Thermal Treatment of Woody Char from Fast Pyrolysis Process
Get PDFInfluences of thermal treatment conditions of temperature, reaction cycle and time, and purge gas type on nanocarbon formation over bio-chars from fast pyrolysis and effects of thermal reaction cycle and purge gas type on bio-char surface functional groups were investigated by temperature-programmed desorption (TPD) and temperature-programmed reduction methods. Nanospheres occurred on bio-chars under the activation temperature of 700°C; more nanospheres occurred when temperature increased to 900°C. Further increase of temperature to 1100°C yielded bio-char surfaces covered with a layer of nanospheres between 20 and 50 nm. More carbon nanospheres formed by increasing thermal cycles and reaction time. Scanning electron microscope images of char surfaces showed there were fewer or no nanoparticles produced using H2 as the purge gas and they were porous. TPD results indicated that H2, H2O, CH4, CO, and CO2 in gas phases evolved from chars heated to 1000°C during the first heating cycle. H2 and CH4 peaked at 750 and 615°C, respectively. Both H2O and CO had two peaks, and CO2 had a broad peak. Only trace amounts of H2 and CO were detected in the second cycle. There was no detection for CH4, H2O, and CO2 after the second cycle
Effect of Temperature on Calcium Carbonate Deposition in Situ on Bamboo Fiber and Polymer Interfaces
Get PDFThe objective of this work was to investigate the effect of different reaction temperatures on the mechanical and surface (interface) properties of calcium-carbonate (CaCO3)-filled bamboo fibers and polypropylene (PP) composites. With an ionic reaction of sodium carbonate and calcium chloride aqueous solution at various bath temperatures, CaCO3 particles were successfully deposited in situ on bamboo fibers. Polymer composites were fabricated using treated bamboo fibers as the reinforcement and PP as the matrix. Tensile tests of single fibers and PP composites were performed to determine the mechanical properties at different conditions. Results showed that the treatments improved compatibility between bamboo fibers and PP matrix, and the crystallinity of inorganic materials was affected by the treatment temperature. Compared with the composites reinforced with untreated bamboo fibers, the tensile strength and modulus of composites reinforced with treated fibers increased by 14.58 and 19.66%, respectively
Dissolution of Pulp in Room-Temperature Ionic Liquids: A Comparative Study
No full textThis work aims to synthesize room-temperature ionic liquids (RTILs) by combining cations (ie olefins and alkyl-based imidozalium) and anions (phosphate and chloride). The synthesized RTILs exhibited considerable solubility for pulp at temperatures ranging from 35 to 100°C compared with the typical ILs of 1-butyl-3-methylimidazolium chloride (BminCl), 1-ethyl-3-ethylimidazolium chloride (AeimCl), and 1-ethyl-3-methylimidazolium phosphorous methyl ester (EminMeOPO2H). The mixture composed of AeimCl and EmimMeOPO2H showed a significant decrease in pulp solubility compared with either of the two alone and the RTILs. X-ray diffraction (XRD) analysis indicated that anions probably play significant roles in the decrystallization of pulp through the dissolution-regeneration process. The thermal property of the ILs was investigated using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC)
Technical Note: Feeding Rate as a Consideration Factor for Successful Termite Wood Preference Tests
Get PDFThe percent weight loss (%WL) of a wood sample and termite mortality are indicators of termite wood preference. WL is apparently affected by wood density, even though the same WL values for wood of different densities provide different amounts of wood mass loss. Feeding rate is also a factor for interpreting the results of termite wood preference tests. The wood species used for this study were sengon (Paraserianthes falcataria), pulai (Peronema sp.), and mindi (Melia azedarach), which had densities of 273, 302, and 434 kg·m-3, respectively. Samples of wood from each species were tested against the subterranean termite (Coptotermes curvignathus Holmgren) according to the Indonesian standard SNI 01-7207-2006. The WL for sengon, pulai, and mindi were 37.3, 36.4, and 10.3%, respectively; termite mortality was 24.2, 18.8, and 61.3%, respectively; and the daily feeding rates were 270, 132, and 42 μg per termite, respectively. The resistance class relative to the Indonesian standard was V for sengon and pulai and III for mindi. Higher wood density among these three species tended to be more resistant to subterranean termite attack, as indicated by a lower wood WL, higher termite mortality, and lower termite feeding rate