Wood and Fiber Science (E-Journal)
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MECHANICAL PROPERTIES OF SILICA CELLS IN BAMBOO MEASURED USING IN-SITU IMAGING NANAINDENTATION
Get PDFIn-situ imaging nanoindentation technique was applied to measure the cell wall mechanical properties of silica cells, as well as pure biogenic silica in Moso bamboo (phyllostachys pubescens Mazel). For comparison, the mechanical properties of thick-walled epidermal cells close to these silica cells, as well as bamboo fibers were also measured. The silica cells were found to have a high cell wall hardness of about 1 GPa, nearly two times that of the values observed for the other two types of cells. Furthermore, we found that biogenic silica had a hardness of as high as 2.68 GPa. This explains why silica cells have such high hardness. Conversely, bamboo fibers showed the highest values for indentation modulus, nearly two times greater than that of the other two cell types. This implies silica cells and epidermal thick-walled cells have a large microfibrillar angle compared to bamboo fibers. The present results imply that silica cells with exceptional high hardness may be regarded as a model nanocomposite with cell wall polymers reinforced with SiO2 nanoparticles. More research is needed on silica cells, as they might provide inspiration for the development of innovative SiO2/wood composite products with both high hardness and low production costs
USING COMPUTED TOMOGRAPHY SCANNING TECHNOLOGY TO EXTRACT VIRTUAL WOOD CORES, DERIVE WOOD DENSITY RADIAL PATTERNS, AND TEST HYPOTHESIS ABOUT DIRECTION, CORE SIZE, AND YEAR OF GROWTH
Get PDFComputed tomography (CT) scanning technology was used to collect millions of three-dimensional data called “CT numbers”, on two sets of white spruce (Picea glauca [Moench] Voss) wood disks. Data collected were then converted to wood density estimates using a calibration equation for wood. Virtual wood cores with three different sizes (i.e., 1 voxel – the smallest volumetric unit on which a CT number was computed, 5 mm and 12 mm in diameter) were extracted from pith to bark and in four orthogonal directions. This made it possible to test the effects of core direction and size on the wood density estimates obtained. The average values as well as the radial patterns of wood density as estimated from CT scanning data were found to be typical of the values and patterns reported for the white spruce tree species in the literature, especially in relation to cambial age as the experimental trees were of different ages. In conclusion, wood science application of CT scanning technology allows extracting data subsets in 3D to perform density estimation, pattern analysis and hypothesis testing, and the results are valuable complements to those obtained with other technologies such as X-ray densitometry
FIELD TEST OF A NOVEL NON-DESTRUCTIVE TESTING DEVICE ON WOOD DISTRIBUTION POLES
Get PDFA field test was performed on 50 utility poles that had been removed from service. The poles were non-destructively tested with a novel device, the PoleXpert. The poles were then destructively tested. Results indicated that the device’s output correlated well with the actual bending strength of the poles. As such it appears that the device has potential to identify weak or structurally compromised poles. Seventeen (17) of the poles were reinstalled in the ground and tested. The remainder 33 poles were tested horizontally in a pole-testing fixture. The device demonstrated positive correlation in both situations
SERVICEABILITY SENSITIVITY ANALYSIS OF WOOD FLOORS ALLOWING FOR SHEATHING DISCONTINUITIES
Get PDFThis paper compares several design criteria for preventing unacceptable wood floor vibrations under occupant-induced loads and presents a sensitivity analysis based on static and dynamic responses of wood floor with engineered I-joist. Responses of floors with continuous and discontinuous (jointed) sheathing are compared. To accomplish this task, a user interface for the OpenSees finite element analysis program was developed. The interface was created in Microsoft Excel and allows user input for various floor system properties which are used as input into OpenSees. Results from the OpenSees program are imported into the user interface and compared against multiple acceptance criteria which have been established by researchers to determine fitness of the floor system. It was determined that a system with a 1.92 kPa (40 psf) uniform load modeled with one continuous piece of sheathing covering the entire floor system produced deflections which averaged 32 percent to a maximum of 45 percent lower than a floor system modeled with jointed sheathing. For a 1 kN (225 lb) force applied at the center of the floor, floors with jointed sheathing had an average of 12 percent and a maximum of 15 percent larger displacements compared to the floors with continuous sheathing. Floors with jointed sheathing had an average of 8 percent and a maximum of 12 percent lower unoccupied natural frequencies compared to the floors with continuous sheathing. Floors with jointed sheathing had an average of 10 percent and a maximum of 13 percent lower occupied natural frequencies compared to the floors with continuous sheathing. Floors with jointed sheathing also had an average of 17 percent and a maximum of 38 percent larger frequency-weighted one-second root-mean-square acceleration values compared to the floors with continuous sheathing. The results show that great care must be taken when simplifying the sheathing setup on a floor model since the results create the illusion of better serviceability performance than actual installed floors will achieve
MCIROFIBRIL AGGREGATES IN PRETREATED BAMBOO FIBERS ANALYZED WITH ATOMIC FORCE MICROSCOPY
No full textFiber primary cell walls of Ci bamboo (Neosinocalamus affinis) were analyzed with an atomic force microscope (AFM) to determine the arrangement of microfibril aggregates and the effect of pre-treatments (ultrasonic treatment and different drying ways) on the arrangement and dimension of microfibril aggregates and the cell wall topography. The microfibril aggregates in primary cell walls of bamboo fiber showed a randomly interwoven structure. Differences in the spacing between microfibril aggregates observed from the AFM phase images and the microfibril aggregates diameter determined from the AFM height topography of the nanostructure of primary cell walls of bamboo fiber were found relevant to the pre-treatments during the sample preparation. Besides, the microfibril aggregates in primary cell walls of bamboo were actually the aggregations of different numbers of cellulose fibrils. Moreover, the ultrasonic treatment could increase the roughness of bamboo fiber and exposure of microfibril aggregates. The data suggest that sample preparation and pre-treatments should be considered relevant to the arrangement and dimension of microfibril aggregates as well as the topography in studying the nanostructure of cell walls with AFM.
A TOOL FOR EVALUATING THE QUALITY OF LAMINATED PARTICLEBOARD COUNTERTOP
Get PDFTo evaluate the quality of laminated particleboard, a typical type of laminate was used in laminating particleboard with operational parameters similar to industry operation. Pull-off tests using Elcometer 510 were conducted. In addition, panel vertical density profiles (VDP) and the pH of particleboard at different layers were tested. The results showed that the laminated panel bonded by polyvinyl acetate (PVA) glue had higher pull-off strength than that of the phenol formaldehyde (PF) glue within corresponding sanding thickness. Sanding off 0.0762 mm resulted in higher pull-off strength than sanding off 0.0254 mm. The laminates had the highest pull-off strength when the PB were sanded off 0.0762 mm and glued by PVA. This has provided a solution to improve lamination pull-of strength for industry. The test results have also shown that the laminated panels produced in the manufactures have the potential to be improved. It also indicates that Elcometer 510 is a good tool to evaluate the particleboard lamination quality
Self-Activatin Process to Fabricate Activated Carbon from Kenaf
Get PDFSelf-activation takes advantage of the gases emitted from the pyrolysis process of biomass to activate the converted carbon, so that a high performance activated carbon is obtained. Kenaf fiber, one type of biomass, was self-activated into activated carbon. The Brunauer–Emmett–Teller (BET) specific surface area (SABET) of non-activation and self-activation pyrolyzed at 1100°C for 2 hours were analyzed and obtained as 252 m2/g and 1,280 m2/g, respectively, with 408% difference. The results showed that the highest SABET (1,616 m2/g) was achieved when a kenaf fiber was pyrolyzed at 1,000°C for 15 hours. A linear relationship was shown between the ln(SABET) and the yield of kenaf fiber based activated carbon through the self-activation process. The study also showed that a yield of 9.0% gave the highest surface area by gram kenaf fiber (80 m2 per gram kenaf fiber), and the yields between 7.2 – 13.8% produced a surface area per gram kenaf fiber that was higher than 95% of the maximum surface area by gram kenaf fiber
AN INVESTIGATION ON WINDMILL PALM LEAF SHEATH FIBER POWDER-BASED ACTIVATED CARBON FOR DYE ADSORPTION
Get PDFWindmill palm sheath fiber (WPF) is an abundant agricultural by-product and useful resource. To increase its valuable qualities and usefulness, we proposed to prepare WPF-based activated carbon (WPFAC) as a novel adsorbent for adsorbing methylene blue (MB), with the specific aims for pollution treatment. The porous features of WPFAC were assessed based on nitrogen adsorption, and the adsorption capacity was studied by investigating the effect parameters of contact time, initial concentration, pH and temperature. Research results show a combination microporous and mesoporous structure of WPFAC with BET surface of 668.81 m2/g. WPFAC exhibits excellent adsorbing performance, and the maximum monolayer adsorption capacity is up to 51.78 times higher than other absorbents. Meanwhile, the adsorption capacity increased accordingly as the parameters increase. For better understanding the adsorption behavior, isotherms, kinetics and thermodynamic were studied by using the equilibrium data. Investigation results illustrated the equilibrium data were well consistent with the Langmuir isotherm, with a maximum monolayer adsorption capacity of 253.16, 289.85, and 303.95 mg/g at 30, 40, and 50 °C, respectively. The adsorption kinetics followed the pseudo-second-order kinetic model. Thermodynamic parameters: standard enthalpy (ΔH0), standard entropy (ΔS0), and standard free energy (ΔG0) indicated an endothermic and spontaneous absorbing process. WPFAC is a promising material which has high utility values for its amazing adsorption capacity