Sen'i Gakkaishi
Online ISSN : 1884-2259
Print ISSN : 0037-9875
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Volume 56, Issue 9
Displaying 1-11 of 11 articles from this issue
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  • Changes of Mechanical Properties and Phase Separated Structure of Thermotropic Polyurethane Fiber under the Periodic Elongation and Recovery
    Midori Takasaki, Yutaka Ohkoshi, Yasuo Gotoh, Masanobu Nagura
    Article type: scientific monograph
    Subject area: Infomation Science
    2000 Volume 56 Issue 9 Pages 428-434
    Published: 2000
    Released on J-STAGE: October 31, 2001
    DOIhttps://doi.org/10.2115/fiber.56.428
    JOURNAL FREE ACCESS
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    The periodic structure, which is composed of hard and soft domains, oriented along the fiber axis in the melt spun thermotropic polyurethane fiber. The phenomena of structure and mechanical properties change can be divided into three extension ratio ranges, less than 1.2, from 1.2 to 1.5, and more than 1.7. There are little changes in the structure and the properties observed for extension ratio less than 1.2. The periodic structure became apparent at the extension ratio 1.2-1.5. The short relaxation time component, the maximum stress, and the energy loss were steeply increased at that extension range. The periodic structure vanished by over 1.7 times extension, but it reconstructed by the relaxation process. The residual strain and the loss energy decreased obviously by the previous extension-recovery. For example, the ratio of 2nd cycle residual strain to the 1st cycle one was about 30% for extension ratio 1.5 and 1.7, whereas it was 13-19% for extension ratio more than 2.
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  • Synthesis of Hydroxypropyl Derivatives of Chitin and Chitosan and Observation of Phase Behavior of Their Aqueous Solutions
    Daisuke Asahina, Tomoyuki Matsubara, Yoshiharu Miyashita, Yoshiyuki Ni ...
    Article type: scientific monograph
    Subject area: Infomation Science
    2000 Volume 56 Issue 9 Pages 435-442
    Published: 2000
    Released on J-STAGE: October 31, 2001
    DOIhttps://doi.org/10.2115/fiber.56.435
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    Hydroxypropyl (HP) derivatives of chitin and chitosan with different degrees of substitution were synthesized via etherification of the polysaccharides with propylene oxide under various conditions. Molecular structure of the HP derivatives was characterized by 1H and 13C NMR spectroscopy. On the basis of the spectral data, we proposed the equations to determine the molar substitution (MS), degree of pendants (DPs) and degree of substitution (DS) of the HP derivatives obtained. Phase behavior and liquid-crystalline characteristics of aqueous solutions of the derivatives were also examined by light absorption and polarized optical microscopy (POM). Aqueous solutions of highly substituted HP derivatives were phase-separated and became turbid at an elevated temperature. The observed cloud point varied sensitively, depending on the degree of substitution and molecular weight of HP derivatives, concentration of the solutions, and coexistence of inorganic salts. POM observations revealed that the formation of an optically anisotropic monophase prevailed in the concentrated solutions of highly substituted HP derivatives.
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  • Damping Behavior of Chlorinated Polyethylene/N, N′-Dicyclohexyl-2-benzothiazolylsulfenamide Organic Hybrid
    Kiyohiro Inoue, Tetsuya Itou, Ikuma Matsuzaki, Hajime Kaneko, Masanori ...
    Article type: scientific monograph
    Subject area: Infomation Science
    2000 Volume 56 Issue 9 Pages 443-448
    Published: 2000
    Released on J-STAGE: October 31, 2001
    DOIhttps://doi.org/10.2115/fiber.56.443
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    Damping behavior of organic hybrid damping materials prepared from a mixture of chlorinated polyethylene (CPE) and N, N′-dicyclohexyl-2-benzothiazolylsulfenamide (DBS) was investigated by means of dynamic mechanical analysis. DBS content dependence on the damping behavior can be divided into two characteristic regions. At contents lower than 66wt%, the maximum value of loss modulus and loss tangent increase linearly with DBS content; however, at contents higher than that value, they become nonlinear. Temperature dependence of loss tangent shows that there are two loss peaks for the highly filled mixtures. The first peak is broad with tan δ of about 5∼10, while the second peak is rather sharp at high temperature with tan δ>10. By differential scanning calorimetry (DSC), the crystallization peak was observed only for the highly filled mixture. The finding that incorporation of a small amount of CPE into DBS matrix can improve the DBS crystallinity is very important for the development of novel hybrid materials.
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  • A Novel Design Principle of Geotextile-Reinforced Banks
    Takashi Komori, Mitsuo Kimura, Motoyoshi Itoh
    Article type: scientific monograph
    Subject area: Infomation Science
    2000 Volume 56 Issue 9 Pages 449-455
    Published: 2000
    Released on J-STAGE: October 31, 2001
    DOIhttps://doi.org/10.2115/fiber.56.449
    JOURNAL FREE ACCESS
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    A new principle in the design of a bank reinforced by geotextiles is proposed without use of the convention called the rule of triangular tension distribution; this rules how the total textile tension required to improve the horizontal tenacity of a bank is allocated to the laid textiles depending on each lay depth. As pointed out earlier by the authors, this conventional distribution seems to be assumed on no or at least an unidentifiable physical ground. The new rule of allocation of tension is based alternatively on the distribution over lay depth of the minimum force to pull out each textile from the front or back of an interface imagined as a potential slip site in the bank. The theory can estimate at every lay depth the strength of textile material which is required by the necessary and sufficient reinforcement to guarantee the bank the specified safety for all possible supposition of slip interface.
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  • Stoichiometric Analysis of the Weight-Decrease in the Enzymatic Treatment of Cotton Fiber: A Guide to Real-Time Monitoring System for the Treatment
    Shigeyuki Nakano, Ryuji Hirase, Kazuhiko Komurasaki, Ahmed EL Salmawy, ...
    Article type: scientific monograph
    Subject area: Infomation Science
    2000 Volume 56 Issue 9 Pages 456-461
    Published: 2000
    Released on J-STAGE: October 31, 2001
    DOIhttps://doi.org/10.2115/fiber.56.456
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    Enzymatic hydrolysis of cotton fiber was studied in detail to find out a good way to monitor the weight loss of fiber precisely. In this enzymatic treatment the linear relationship between the weight loss and the glucose formation was confirmed. Stoichiometric analysis of the hydrolysis products revealed that both glucose and oligosaccharides are formed from cellobiose in a constant ratio to give the linearity. This may be attributed to the cellobiose hydrase and polymerase activities involved in the cellulase used (originated from Filamentous fungi). Based on this finding, a new monitoring system using the chemi-luminescence of luminol was examined for assessing the glucose formation, which was related with the total weight loss of cotton fiber. This method is superior to other methods in terms of shortness of measuring time and applicable for monitoring the weight loss of dyed fabrics.
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  • Fibrillation Behavior of Silk Fibers from Japanese-oak-silkworm, Antheraea yamamai
    Yutaka Kawahara, Masaki Tsuji, Tomohiko Hananouchi, Hidetoshi Tamura, ...
    Article type: scientific monograph
    Subject area: Infomation Science
    2000 Volume 56 Issue 9 Pages 462-465
    Published: 2000
    Released on J-STAGE: October 31, 2001
    DOIhttps://doi.org/10.2115/fiber.56.462
    JOURNAL FREE ACCESS
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    Silk fibers from Japanese-oak-silkworm, Antheraea yamamai, were fibrillated via Japanese handmade-paper making method, and laboratory handsheets were made. Scanning electron microscopy showed that the occurrence of fibrillation followed by tangling between the fibrils is important for the formation of sheets. The morphologies of the fibrils obtained through the fibrillation were investigated by transmission electron microscopy. Two types of fibrils, i.e. the ribbon-like ones and the random-coil-like ones were observed. The wide-angle X-ray diffraction measurement for these fibrils showed an amorphous scattering curve. However, no difference was observed between the infrared spectra for these fibrils and the control fibroin. It seems that the lateral packing of pleated β sheet structure of fibroin of Japanese-oak-silk is loosened slightly when the fibrillation proceeds to a certain degree.
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