The Young’s modulus and shear modulus of solid wood (Sitka spruce) in the longitudinal-radial (LR) and longitudinal-tangential (LT) planes were obtained from the symmetric four-point bending and asymmetric four-point bending tests under various span/depth ratios. Independently from the bending tests, the Young’s modulus and shear modulus were measured from the tension and Iosipescu shear tests, respectively, and the validity of the bending tests was examined by comparing the results of these various tests. The Young’s modulus and shear modulus could be determined accurately when using both the four-point testing data obtained in the appropriate range of span/depth ratios, which was approximately from 25 to 30.
As an effective utilization method of the oil palm trunks, particleboards were prepared using vascular bundles of the trunks. The vascular bundles were obtained by separating parenchyma from a trunk veneer using a hammer mill. The boards with density of 0.6 g/cm3, 0.7 g/cm3 and 0.8 g/cm3 and with resin content of 5%, 10% and 15% were prepared and comparatively evaluated. Isocyanate was used as an adhesive. Modulus of rupture, modulus of elasticity and thickness swelling of the specimens taken out from each board were measured according to JIS A 5908. Following results were obtained. 1) More than 90% of the particles were 20 mm to 50 mm in length. The particles of 20 mm to 30 mm accounted for 35% of the total. Some particles contained parenchyma, attached to the surface of a vascular bundle, but most of particles were vascular bundles only. 2)MOR of specimens obtained from a board with resin content of 10% or more sufficiently satisfied JIS A 5908. MOR and MOE of a board with resin content of 10% or 15% increased with increasing resin contents and densities on boards. The fracture strains were not changed with the resin contents and densities. MOR and MOE of the specimens obtained from boards with all conditions were higher than those prepared from purely oil palm trunk. 3)Thickness swelling of the specimens obtained from a board with resin content of 10% or more sufficiently satisfied JIS A 5908. Thicknesses swelling of the specimens obtained from board with all conditions were lower than coefficient of swelling of those prepared from purely oil palm trunk in the radial direction.
This paper proposed molding of wood powder with natural binder, which is composed of sucrose and citric acid, for effectively fabricating wood product without synthetic resins. In the proposed method, optimization of particle size is important for improving the thermal fluidity during the molding and reducing the milling cost. Thermal flow testing of wood powder with natural binder was carried out in order to investigate the effect of particle size on thermal flow of wood powder with natural binder. When binder content was 30~40 wt%, the thermal flow pressure changed depending on the particle size, and the optimum one was the particles, which passed 2.8 mm mesh sieve and be on 2.0 mm mesh sieve, for decreasing the flow pressure. In a case that the particle size was smaller than the optimum size, the flow pressure increased because the slipping plane propagation was prevented. In the case that the particle size was larger than the optimum size, the flow pressure also increased due to an increase in the force for crashing the particles. Based on the results of thermal flow testing, molding testing was carried out. When the particle size was optimum, products were fabricated successfully in a wide range of binder content, which was 30~50 wt%, because the flow pressure was low.
Cellophane, which is a conventional cellulose film regenerated from viscose, has been used for a long time as a base for tapes and food packaging materials etc. This is because it has durability against many chemicals and has useful properties such as easy-cut and bacterial barrier properties. However, some drawback of moisture absorption and deformation remains. Thus, some improvements such as dimensional stabilities under high humidity are required. Cellophane has been manufactured from a solution of pulp dissolved as cellulose xanthate using harmful carbon disulfide. That is, much attention has been focused on ionic liquids (IL) as a novel solvent that can easily dissolve cellulose and is easier to be handled than carbon disulfide. Some papers reported that IL and IL/co-solvent systems can work as esterification media without any catalyst. In this study, we prepared cellulose/cellulose acetate films by coagulation method of blended ionic liquid solution to impart hydrophobicity to the regenerated cellulose film. The films were characterized by Fourier transform infrared spectroscopy (FT-IR), wide angle X-ray diffraction (WAXD), small angle X-ray scattering (SAXS), viscoelastic measurements, visible light spectroscopy, and contact angle measurements. In conclusion cellulose and cellulose acetate can be blended without phase separation to inhibit crystallization of each other. The third component, glycerol, also has a function of inhibiting crystallization of cellulose and cellulose acetate. It improves the film transparency and the molecular mobility of the celluloses.
Liquid-crystalline behavior of phenylcarbamate derivatives of cellulose in vinyl monomer solvents was investigated, and then calcium carbonate (CaCO3) mineralization was conducted in colored films wherein a cholesteric structure of the cellulosic derivatives was immobilized by polymerization and cross-linking of the solvent monomer(s). Two sorts of derivatives, cellulose phenylcarbamate (CPC) and cellulose 3-chlorophenylcarbamate (3Cl-CPC), were used. Although both derivatives were hardly soluble in anionic monomers such as acrylic acid (AA) at high concentrations (>30 wt%), CPC formed a left-handed cholesteric mesophase in a mixture of N-vinyl pyrrolidone (VP)/ AA (10:0–9:1 in wt.) and 3Cl-CPC assumed a right-handed cholesteric arrangement in VP/AA/dimethyl sulfoxide (DMSO) (5:0:5, 3:2:5, or 2:3:5 in wt.); each mesomorphic solution imparted a vivid cholesteric color. By UV-induced polymerization and subsequent washing processes for the lyotropics, the original cholesteric architectures were successfully fixed into the resulting films of CPC/poly(N-vinyl pyrrolidone) (PVP), CPC/poly(N-vinyl pyrrolidone- co-acrylic acid) (P(VP-co-AA)), 3Cl-CPC/PVP, and 3Cl-CPC/P(VP-co-AA). After soaking the liquid-crystalline films in an aqueous salt solution containing Ca2+ and HCO3−, we obtained calcic mineral-hybridized polymer composites. Wide-angle X-ray diffractometry (WAXD) and energy-dispersive X-ray (EDX) spectroscopy revealed that CaCO3 crystals (in calcite form) were deposited inside the films when the anionic AA was present as a matrix component. In thermogravimetric analysis (TGA), it was observed that the flame resistance of the mineralized films was improved in the high-temperature range (>300°C), although the decomposition temperature tended to fall.
Intrasheet interaction of native cellulose was investigated at the MP2 and DFT(B3LYP) levels of theory, employing various one-sheet crystalline models. Our MP2//DFT(B3LYP) calculations for the smallest two dimensional dimeric system possessing a short O6-H···O3’ hydrogen bond and a long O6-H···O2’ one indicated that the interaction energy between the two dimers (cellobiose) was 8.4 kcal/mol per one glucosyl residue. Energy contribution of the short O6-H···O3’ hydrogen bond was estimated to be 5.8 kcal/mol, which was ~70 % of the total interaction energy, on the assumption that all part of the intrasheet interaction energy was derived from the intermolecular hydrogen bond energy. Interestingly, the long O6-H···O2’ hydrogen bond provided somewhat large contribution of 2.6 kcal/mol, ~30 % of the total interaction energy. The DFT(B3LYP) method presented similar results. The DFT(B3LYP) method was then applied to larger crystalline sheet models, whose degree of polymerization was up to 8 with the chain dimension being up to 3. Their intrasheet interaction energies per one glucosyl residue did not significantly depend on the degree of polymerization and the chain dimension, which suggests that the above interaction energy can be applied to discuss the stabilization of the real native cellulose.
Because of lacking at thermoplasticity in cellulose, it requires solution states for molding processing. A typical example is viscose, which requires the use of a multiple solvent system including toxic. In order to improve the disadvantage, cellulose was dissolved in an ionic liquid mixed solvent and its solution characteristics were evaluated in the present study. Another method for imparting thermoplasticity to cellulose is chemical modification. Thus, an attempt was also made to acetylate cellulose in the ionic liquid mixed cellulose solution. Despite the fact that the solvent contains dimethyl sulfoxide, which causes the Pummerer rearrangement preventing esterification, cellulose acetate with a degree of substitution of 2.7 or higher was successfully prepared. The films were prepared by coagulation of the solution, and the film characteristics were evaluated by measuring their viscoelasticity. It was found that cellulose and cellulose acetate films obtained from the solvent have almost the same viscoelastic properties as commercially available ones. In addition, the solution characteristic in the ionic liquid mixed solvent of the obtained cellulose acetate was examined.
The effect of sigma phase precipitation was revealed on toughness and corrosion resistance of SUS329J4L duplex stainless steel cooled under continuous and inconsistent speed．The prototype vacuum furnace was used to produce the practical heat treatment specimens through adjusting the heat transfer coefficient at interface between steel and nitrogen gas，which was controlled with fan rotating speed．The time constant （τ） derived from the measured temperature profile well corresponded to the calculated one by using the heat transfer coefficient and the physical properties of specimens as well as their characteristic length．The absorbed energy can be sorted according to time constant，i.e．, the same as water quenched one at less than 279s，rapidly decrease between 279~573s，and gradually decrease at more than 573s．These transitions were caused by the increase in cleavage fracture due to sigma phase precipitation. Corrosion in 6% FeCl3 solution at 313K also became sever with the time constant increase，but the surge of corrosion rate happened at larger time constant than that of the absorbed energy measured in impact test．