材料
Online ISSN : 1880-7488
Print ISSN : 0514-5163
ISSN-L : 0514-5163
71 巻, 7 号
選択された号の論文の13件中1~13を表示しています
資料
  • 巽 大輔, 横内 唯, 田中 栄行, 岩田 一平
    2022 年 71 巻 7 号 p. 579-584
    発行日: 2022/07/15
    公開日: 2022/07/20
    ジャーナル フリー

    Cellulose films and fibers were prepared by using an ionic liquid solvent (Tetrabutylammonium acetate / Dimethyl sulfoxide). The characteristics of the films and the fibers were evaluated mainly from the viewpoint of crystallinity. The crystallinity of the films prepared with water as a coagulation solvent showed the highest value, whereas it decreased when other organic solvents were added to the coagulation bath. The diffraction intensity from the (1 1 0)plane, that is a so-called hydrophilic plane of cellulose II crystal, of the water-coagulated film was remarkably high in the X-ray diffraction profiles. It suggested that the surface characteristics of the film can be changed by changing the coagulation solvent. The crystallinity of the films was also affected by the machine speed of film formation and it showed the highest value when the speed was 50 m/min. For the fiber sample, the crystallinity of the obtained fiber increased with the draw ratio (up to 3 times). It also increased with the cellulose concentration of the dope. The cellulose content of the raw material affected the crystallinity and the strength of the obtained fibers. These results can be a guideline for molding films and fibers from cellulosic raw materials through ionic liquids.

  • 吉原 浩, 吉延 匡弘, 丸田 誠
    2022 年 71 巻 7 号 p. 585-590
    発行日: 2022/07/15
    公開日: 2022/07/20
    ジャーナル フリー

    In this study, in-plane and out-of-plane shear moduli of paperboard were obtained from free-free torsional vibration (FFTV) tests under various specimen configurations. Independently of the torsional vibration tests, 45° off-axis tensile tests were conducted to measure the in-plane shear modulus, and the obtained results were compared with those by the torsional vibration tests. The results are summarized as follows: (1) When a single specimen was used, obtaining the in-plane shear modulus from the FFTV test accurately was difficult because of the strong orthotropy in the paperboard. However, the accuracy was improved when specimens with various widths were used. (2) The in-plane shear modulus obtained from the FFTV tests was significantly greater than that obtained from the 45° off-axis tensile test because of the effect of the lamination construction of the paperboard. (3) The out-of-plane shear modulus was considerably lower than the in-plane shear modulus. The inaccuracy in measuring the in-plane shear modulus using a single specimen was enhanced by the low value of the out-of-shear modulus. (4) The out-of-plane shear modulus in the plane defined by the machine and thickness directions was significantly greater than that in the plane defined by the cross-machine and thickness directions.

論文
  • 石井 大輔, 谷 智仁, 林 久夫
    2022 年 71 巻 7 号 p. 591-596
    発行日: 2022/07/15
    公開日: 2022/07/20
    ジャーナル フリー

    Esterification of cellulose with 4-phenylphenoxy acetic acid (PPA) in 1-butyl-3-methlimidazolium chloride (BMIMCl) has been performed with the aim of preparing novel liquid crystalline cellulose derivative. Effect of reaction conditions, such as type of esterification reagents and ionic species, on the thermal properties and solubility of the polysaccharide derivatives has been investigated. As the result, cellulose 4-phenylphenoxyacetate (CPA) with the maximum degree of substitution (DS) of 1.17 was attained by using 1,3-diisopropylcarbodiimide as the esterification reagent and by applying 8 molar parts of PPA against 1 molar parts of hydroxyl groups in cellulose. The esterification reaction was performed at 100 °C for 72 h without basic catalyst. The CPA retained almost constant dynamic storage modulus up to 120 °C and showed the 10 % weight decrease at 285 °C, that was 57 °C higher than the original cellulose. On the other hand, within the range of DS attained, CPA did not form mesophase on heating or in the solution state in dimethylsulfoxide and N,N-dimethylacetamide.

  • 大塚 友加里, 堀山 彰亮, 伊藤 貴文, 神代 圭輔, 古田 裕三
    2022 年 71 巻 7 号 p. 597-602
    発行日: 2022/07/15
    公開日: 2022/07/20
    ジャーナル フリー

    The purpose of this study was to clarified the mechanism of dimensional stabilization of wood treated with azelaic acid. In this study, the effects of heating temperature of azelaic acid treatment on the weight percent gain, the bulking, and the hygroscopicity of treated wood were investigated in detail. Furthermore, the effects of heating temperature on the reaction between azelaic acid and wood components were also investigated, and the mechanism of dimensional stabilization at each heating temperature was considered. The bulking of treated wood was almost constant at heating temperature in the range of 70-80°C, increased with the temperature in the range of 90-130°C, and was almost constant in the range of 130-150°C. The swelling of treated wood by moisture absorption was almost constant in the 70-80°C range, decreased with the temperature in the range of 90-130°C, and increased with the temperature in the range of 130-150°C. The moisture content of treated wood after absorption was almost constant in the range of 70-100°C, and decreased with the temperature in the range of 110-150°C. When the IR spectra of treated wood heated at 90°C and 130°C were compared, it was clarified that the azelaic acid and the wood were esterified at 130°C. It was suggested that this reaction was contributed to the decrease of moisture content of treated wood. The bulking of treated wood was significantly contributed to dimensional stabilization from 70°C to 130°C, and it was suggested that there were factors other than the bulking that slightly decreased dimensional stability from 130°C to 150°C.

  • 坂井 覚, 村田 功二, 仲村 匡司
    2022 年 71 巻 7 号 p. 603-607
    発行日: 2022/07/15
    公開日: 2022/07/20
    ジャーナル フリー

    The collision between a free-falling ball and wood was observed with a digital camera, and the collision parameters (e.g., the coefficient of restitution, COR) were evaluated. A charge-coupled device (CCD) camera (600 fps) was used to obtain the COR, and a high-speed camera (54000 fps) was used to measure the contact time of the ball. In addition, an indentation test using steel balls was performed to evaluate the surface properties and the corresponding results were compared with the results of the collision test. Consequently, with respect to the collisions between the ball and wood, it was observed that the COR depends on the density of the wood, and either elastic or inelastic collisions may occur. In inelastic collisions, there was a correlation between the contact time of the ball and the COR. For some tree species, such as Melia azedarach, the contact time deviated from the relationship observed among other species. In addition to the density, the tissue structure of the wood, such as the annual ring or radial tissue, may influence the contact time. Permanent dents were observed on the wood surface during the inelastic collisions. Furthermore, the surface density and COR slightly increased owing to the plastic deformation of the dents.

論文
  • 屋敷 和秀, 真田 和昭, 松下 直人, 永田 員也
    2022 年 71 巻 7 号 p. 609-616
    発行日: 2022/07/15
    公開日: 2022/07/20
    ジャーナル フリー

    Safety glasses used in machine tools require good impact and solvent resistance, and high transparency. These requirements can be satisfied by glass/polycarbonate (G/PC) laminated safety glass incorporating acrylic interlayer (ACIL). We focused on cellulose nanofibers having a diameter of a few dozen nanometers and a high aspect ratio as a filler in ACIL to enhance the impact resistance of G/PC laminated safety glass. In previous research, the G/PC laminated safety glass incorporating ACIL with CNFs (CNF/ACIL) showed an enhanced impact resistance. However, the effect of the adhesive properties of CNF/ACIL on the impact resistance of G/PC laminated safety glass incorporating CNF/ACIL is unclear. The objective of this study was to investigate the adhesive strength at G-CNF/ACIL and PC-CNF/ACIL adhesive interfaces. Cleavage tests and tensile shear tests were performed on specimens with G-CNF/ACIL and PC-CNF/ACIL adhesive interfaces, and the effects of loading mode and CNF concentration in ACIL on the adhesive strength of the specimens were discussed. In addition, finite element analysis (FEA) of the drop weight tests of the G/PC laminated safety glass considering adhesive strength at interfaces was carried out using LS-DYNA. As a result of experiments, the adhesive strength of the specimens with G-CNF/ACIL and PC-CNF/ACIL adhesive interfaces decreased when CNF concentration in ACIL increased. Also, damage states in fracture surfaces of the specimens with G-CNF/ACIL adhesive interface were changed by increasing CNF concentration in ACIL. However, the fracture surface of the specimens with PC-CNF/ACIL adhesive interface showed the same damage state at different CNF concentrations in ACIL. As a result of finite element analysis, attenuation of the predicted velocity of impactor after collision became stronger when shear failure stress of PC-ACIL adhesive interface in the G/PC laminated safety glass increased.

  • 山田 宏, 関 友則, 山本 誠
    2022 年 71 巻 7 号 p. 617-622
    発行日: 2022/07/15
    公開日: 2022/07/20
    ジャーナル フリー

    The materials used and mix proportion for repair materials differ depending on the required performance such as shrinkage. In general, repair materials have a lower water-cement ratio than regular ready-mixed concrete. In addition, the particle size of the fine aggregate used for repair materials has been adjusted in consideration of workability. Aggregate has the effect of restraining the shrinkage of cement-based materials. Although the effect of coarse aggregate size on the shrinkage characteristics of concrete has been reported, the effect of fine aggregate size on the shrinkage characteristics of mortar has hardly been investigated. Therefore, we investigated the effect of the particle size of the fine aggregate on the autogenous shrinkage and drying shrinkage of the mortar with W/C=35% assuming the repair materials. As a result, it was clarified that the particle size of fine aggregate affects the autogenous shrinkage strain and drying shrinkage strain of mortar. In the range of S/C=1-1.5, it was clarified that the larger the F.M., the smaller the autogenous shrinkage strain. It was also clarified that the larger the S/C and the larger the FM, the smaller the drying shrinkage strain tends to be.

  • 小林 孝一, 新田 和音
    2022 年 71 巻 7 号 p. 623-630
    発行日: 2022/07/15
    公開日: 2022/07/20
    ジャーナル フリー

    In this study, the influence of cracks that have been generated in the cover concrete by the hand chipping on the current distribution along the rebar to which the cathodic protection is applied. As the first step, with the specimens made of mortar and steel plate, it was found that the large crack nearby the steel plate affects the current distribution. In order to simulate the electric potential/current flow distribution by the cathodic protection, an analytical model with two dimensional FDM was built. As the second step, in order to investigate the influence of the crack in concrete on the distribution of the corrosion prevention current in the structure, the analytical model was applied to the structure. It was found by the simulation that cracks do not give fatal adverse effects on the effect of cathodic protection, as long as very large cracks which cannot be found in the application of the cathodic protection are not generated.

  • 島本 由麻, 萩原 大生, 鈴木 哲也, 阿部 幸夫, 大高 範寛, 原田 剛男, 藤本 雄充
    2022 年 71 巻 7 号 p. 631-636
    発行日: 2022/07/15
    公開日: 2022/07/20
    ジャーナル フリー

    In agricultural canals, the plate thickness of steel sheet piles decreases locally in the tidal zone and the cross section is lost. Degradation of structural performance can lead to the occurrence of sudden accidents. It is necessary to evaluate the corrosion condition and thickness of steel sheet piles by periodic investigation. In this paper, the thickness of the steel sheet piles is evaluated by machine learning of digital images (RGB images and infrared images) taken by UAV. As a result, the random forest algorithm can be used to determine whether the plate thickness of the steel sheet piles is greater than the corrosion allowance or not (accuracy: 0.828). A particularly useful parameter is the difference value of infrared temperature between 14:00 and 17:30. Therefore, the plate thickness of steel sheet piles can be evaluated by acquiring infrared images at two time points with large temperature differences.

再録論文
  • 「Materials Transactions」Vol. 61, No. 10, pp1994-2001 (2020) 掲載論文の和訳論文
    佐藤 治道, 小木曽 久人, 山下 順広, 舟田 義則
    2022 年 71 巻 7 号 p. 637-644
    発行日: 2022/07/15
    公開日: 2022/07/20
    ジャーナル フリー

    Miniaturization of bearing rollers used in autos and robots will require a manufacturing system that combines a deposition method that can fabricate thin jigs without defects and a non-destructive inspection method that can detect cracks on such jigs. Here, we are developing a system that uses directed energy deposition (DED), which is a 3D-printing (additive manufacturing, AM) process, to fabricate thin jigs, and then uses laser ultrasonics (LU) to inspect the jigs. Here, deposited layers having a 0.4×0.6 mm2 cross-section were fabricated using DED, and then non-destructively inspected using LU. However, using LU on such a small area has three problems: the effect of overlapping of the excitation and detection laser beams, difficulty in separating the multiple types of waves due to the simultaneous generation, and complexity of the acoustic field. Therefore, first, the acoustic field was examined using the finite element method (FEM), and then LU was used to inspect a small area of the deposited layer using complex discrete wavelet transform. Results show successfully detection of spontaneously occurring cracks, thus confirming the effectiveness of LU for non-destructive inspection of a thin jig.

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