Uniaxial-tension tests were conducted on copy paper to measure the tensile properties, including Young’s modulus, the proportional limit stress, and the tensile strength. Tab-free specimens and specimens with paperboard and emery cloth tabs were prepared. A tensile load was applied using manual grips, including a roller-flat surface grips, wedge grips, and vise grips. The effects of the end-tabs and grips on the measurement of the tensile properties were examined. To obtain the tensile properties of paper, the use of specimens with emery cloth tabs and vise grips is recommended because the failure at the grip and slippage between the specimen and grip can be effectively reduced without using any pressure-adjustable grip, the use of which is determined in several major standards.
To obtain the information about maximum possible tensile deformation of wood, deformation properties of various wood species in lateral tension were studied. In addition, we observed fracture sections of lateral tensile tests in water, in order to examine the effect of anatomy on the deformation properties. Tensile deformation properties were measured in water at 25℃ or 80℃. The test specimens have different angles of the tensile direction to the annual rings (0°, 45°, 90°). The results obtained were as follows. 1) Failure strain of the hardwood specimens were not larger than the specimens of Hinoki at 80℃ in water. 2) At the specimen of angle 45°, failure strain increased proportionally with the decrease in density. 3) In all of specimens, failure strain in water saturated condition were larger at 80℃ than 25℃. However, failure strain were not increased proportionally with the decrease in elastic modulus. This result suggests that softening of wood with moisture and temperature course not only capability for the deformation of cell shapes but also origin of the fracture. 4) Result of observation of the fracture sections of lateral tensile tests, specimen of Keyaki having large pores susceptible to fracture along the sequence of large pores. These results suggest that lateral tensile deformation properties were greatly affected by anatomy. Therefore, in order to increase the tensile deformation it is necessary to deform of cell shapes which affected by density, thermal-softening caused by glass transition of lignin and anatomy, i.e, ray tissue or large pores.
Lumbers must be dried to stabilize their shape, to strengthen, and to prevent corrosion and discoloration before using. Since dehydration usually occurs from outer surface, moisture content in inner layers becomes higher than that of outside. Therefore, higher moisture gradient which may cause unexpected deformation and cracks in materials can be seen after drying. Today, there are some non-destructive techniques to measure moisture content but it is difficult to measure moisture gradient in the thickness direction without sectioning. This study aims to propose an estimation method of moisture slope for whole log based on the eigen-strain methodology in which three-dimensional residual stress distributions can be evaluated from released strains on surface. In the proposed method, shrinkage by dehydration is expressed by eigen-stains which are estimated by an inverse analysis from released strains by strain gauges in processing. When released strains due to moisture gradient are obtained in lumber processing of necessity, the process of this method can be regarded as nondestructive, essentially. In order to prove the effectiveness of this method, numerical simulations were carried out for a log with moisture gradient by using FEM (Finite Element Method). In this analysis, a split liner for prevent splitting was conducted to a log to measure released strains on surface. Moisture gradient could be estimated accurately from released strains when moisture gradient in the thickness direction was relatively steep. However, estimation accuracy became poorer when slope of moisture gradient was relatively moderate. In order to improve the estimation accuracy, a log was split in sequential processes and a formulation was attempted by consolidation those sequential histories. And, estimation accuracy could be improved successfully by adopting the sequential manner.
To control the amount of solute in cell walls of solution impregnated wood using the conditioning process, the mechanisms of solute diffusion into the cell walls and of solvent evaporation from wood under the process were verified. The effect of relative humidity (RH) on temporal variability of swelling, shrinkage, and mass of wood impregnated with an aqueous solution of polyethylene glycol (PEG1540) was examined. The impregnated wood specimen swelled under the conditioning at the RH over 75%. The specimen was indicated to swell when the amount of the PEG polymers in the cell walls increase in this RH range. On the basis of this indication, the temporal variability of increasing rate of the polymers in the cell walls and of evaporating rate of water from the specimen under the conditioning was well explained by the mechanisms of the solute diffusion and the solvent evaporation, respectively. In the RH range, the increasing amount of the polymers in the cell walls increased with the evaporating amount of the water, which increased with the decrease in the RH. These results were supported by the mechanisms of the solute diffusion and the solvent evaporation, respectively. The diffusion mechanism also supported the effect of the history of the RH on the polymer amount in the cell walls throughout the conditioning and subsequent drying in a vacuum. It was concluded from these findings that the solute diffusion into cell walls is able to be controlled by the surrounding vapor pressure of solvent when the polymers (PEG1540) and water are employed as the solute and solvent, respectively.
Recently, a processing technique for applying plastic deformation to a solid wood has been developed. In this study, in order to clarify the effect of die-angle on the extrusion force of a solid wood, the extrusion load with or without lubricant for different die angle was investigated. Solid woods (Japanese cypress) were impregnated with thermoplastic binder (acrylic resin) to improve its fluidity during extrusion. To increase affinity with acrylic resin, the woods were hydrophobized by acetylation before the impregnation. Then the impregnated woods were extruded in a radial direction through the square-shaped dies having different angle (2α = 20°, 30°, 40°, 50°). The results obtained were as follows: The extrusion load was clearly decreased by using the lubricant in every die angle. The results of the no-lubricant condition showed that the extrusion load increased with the decrease in die angle. On the other hand, the extrusion load was little affected by the die angle in the lubricant condition. These results indicated that the extrusion load was strongly affected by the friction between the wood specimen and the tapered die in the no-lubricant condition. Assuming that plane strain condition (no strain in the longitudinal direction of the material) applies to the extrusion, the experimental result was well explained by the theoretical result.
In this study, the effect of water-soluble components on the thermal fluidity of steam-treated bamboo powder was investigated. Bamboo powders were steam-treated at 180 or 200 °C for various steam treatment times. The bamboo powders were then treated with hot water to extract the water-soluble components. The flow rates of steam-treated bamboo powders that were either treated with hot water or not treated were measured using a capillary rheometer. In addition, thermogravimetry (TG) was also used to examine the differences in the thermal characteristics of bamboo powder treated by hot water extraction. The experimental results indicated that the quantity of hot water extract varied with the steam treatment temperature and time. Flow tests showed that bamboo powders not treated with hot water flowed, whereas those treated with hot water did not flow. The flow behavior and flow rate of the untreated powder became stable and high with an increase in the steam treatment time for steam treatment at 180 °C. For steam treatment at 200 °C, the flow behavior was more stable, and the flow rate became the highest by short time steam treatment. TG measurement of the powders suggested that water-soluble contains many volatile components, and the amount of volatile components changed along with the denaturation of the water soluble components. From these results, it was confirmed that not only the quantity of the water-soluble components but also denaturation of the water soluble component affects the thermal fluidity of the steam-treated bamboo powder.
Construction of wooden check dams in Kyoto prefecture started in 1999, and over 130 wooden dams had been constructed as of 2013. However, these wooden check dams were constructed using members with no preservative treatment, and such members are inevitably subject to a decrease in strength due to deterioration over time. Therefore, in order to maintain wooden check dams, it is essential to evaluate the strength and durability of members in field inspections, to acquire data on secular changes in the strength of the members, and to develop techniques to estimate their strength. Accordingly, we conducted bending strength testing of members sampled from existing wooden check dams and measured them with Pilodyn and Resistograph tests. As a result, we found a negative correlation between the Pilodyn and Resistograph measurements and the bending strength. This result suggests that it will be possible to estimate the bending strength of the members in field inspections by using these techniques designed to measure the deterioration of the members. It was also found that members of wooden check dams tend to undergo deterioration faster at the dam wings or the crest of dam wings than at the dam bodies or the spillway crests, and that the rate of such deterioration varies depending on the wooden check dam.
In order to prepare for proposals that would lead to activate Japanese cedar market, including product development of wooden products using Yoshino Sugi, we tried to understand images of Yoshino Sugi which people have for. From the SD method survey that targeted female students, it was found that Sugi tended to be evaluated as having a neutral image. But Sugi also has images of being slightly exclusive, smooth, glossy, and thick. It was also revealed that such factors as color, gloss, and hardness of Sugi affected the outcome of the surveys for image and conformity as material to be used for the interior of houses. In addition, Sugi was assessed as suitable as flooring in the master bedroom and living room by the reason that Sugi had soothing colors and warm atmosphere. So, it will be important that we propose how to utilize such relaxing and warm image and texture of Sugi. We can say, for example, that Sugi has enough potentiality to be used as flooring in the master bedroom and living room of houses in general.
There are the hardwoods such as Konara(Quercus serrata) resources in the forests from Hokkaido to Kyushu abundantly. Because the coppicing of the old tree is difficult, the use of these hardwoods is necessary for the environmental sustainability and protection of the forest. But recently only a very small amount of Konara wood is used. However the bending strength, surface hardness and abrasion resistance of Konara wood suggests usage as a material for furniture and flooring board. But it is difficult to get the long and straight log from Konara tree and large deformation will be occurred due to growing and drying stress. Moreover, dried Konara board become great bowed, crooked and twisted due to changes in moisture content, so high value-added usage is difficult. To improve these defects, the Konara lumber cut short length, dried and laminated to a block. Each block was sawn across glue lines into laminated thin Konara board. These Konara boards surrounding the Sugi plywood can be placed with perpendicularly to the grain direction to father enhance surface hardness, abrasion resistance and bending strength. The dimensional stability of this board is nearly as good as that of plywood. So there is possibility that this board will be high-quality flooring board.
Cu2ZnSnS4 (CZTS) thin films, which are promising for thin-film solar cells with abundant elements, have been fabricated by a simple and cost-effective technique of ultrasonic-atomized mist deposition method. The residual oxygen impurity was removed by successive mist sulfurization technique. The films hence obtained exhibited almost stoichiometric composition of CZTS together with optical bandgap energy of 1.44 eV.
We fabricated Ag electrodes on GaN-based blue light-emitting diodes (LEDs) by direct screen printing with Ag nanoparticle paste instead of commonly used dry processes. After the direct screen printing of Ag nanoparticle pastes on p-type GaN, successive sintering was carried out at 450°C for 30 min. LEDs with a square electrode size of 0.5 mm showed a threshold and operating voltage of 3.3 and 4.4 V, respectively. The maximum emission efficiency was obtained at 13 mA. These results suggest that screen printed Ag electrodes have a potential for use in GaN-based blue LEDs.
The blocks containing amino acid, arginine, were developed as” Environmentally Active Concrete”. It has been reported that the block accelerated to form marine periphytic algae on the concrete block in the actual water area. This work aimed to investigate the behavior of amino acids in the concrete block in laboratory to ensure the control of the existing form of arginine in concrete and the life time of elution. Extraction experiments with water, acid and alkali revealed that about 80% of arginine in the concrete was able to elute into water. And there were adsorption equilibriums between arginine and concrete constituents (cement paste and aggregate) at mildly alkaline pH. A part of arginine has a positive charge at mildly alkaline pH. In addition, the concrete block containing arginine was put in the tank poured marine water by pump. Blocks were periodically salvaged. And time course of elution rates of arginine in the blocks was analyzed. pH of the surface of immersed block decreased till pH8.5. The elution of arginine was considered to be affected by not only diffusion but adsorption equilibrium at stable phase in analogy with Ca in the concrete.