Sen'i Gakkaishi
Online ISSN : 1884-2259
Print ISSN : 0037-9875
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Volume 60, Issue 7
Special Issue on "Syntheses and Industrial Use of Monodispersed Colloidal Particles"
Displaying 1-14 of 14 articles from this issue
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  • Dependence of Electrical Conductivities of Carbon Black Filled Nylon-12 Fibers on Spinning Conditions
    Hirohumi Yanagizawa, Toshiyuki Kodaira
    2004 Volume 60 Issue 7 Pages 203-212
    Published: 2004
    Released on J-STAGE: December 15, 2005
    DOIhttps://doi.org/10.2115/fiber.60.203
    JOURNAL FREE ACCESS
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    Spinning conditions for undrawn carbon black (CB) filled nylon 12 (Ny12) fibers were studied to get electro-conductive fibers with well developed conduction routes of CB. The electrical conductivities of such fibers are assumed to be excellent and less dependent on the circumstance where they are used. Spinning was carried out using a spinneret equipped with a cooling chamber or a heating chamber. Acetylene black (AB) was employed as CB. The average volume resistivity (resistivity) for the fibers tended to decrease with increasing winding speed of the fibers irrespective of the chamber used. The orientation of Ny12 along the fiber axis is considered to be responsible for the lowering of the resistivity. This is because the former increased with increase of the winding speed and it is reasonably assumed that the conduction routes by AB are developed along the fiber axis with the orientation of the matrix polymer. Higher degrees of orientation were achieved for the fibers obtained using the cooling chamber than those using the heating chamber, when the winding speed was kept constant. However, the former had higher resistivity than the latter, when they are compared for the fibers with a same degree of orientation. This was attributed to the variation of a degree of crystallinity. Based on these results, the fibers with AB conduction routes developed effectively and accordingly with lower resistivity could be prepared by choosing proper spinning conditions. The resistivity of the fibers thus obtained remained almost unchanged regardless of the drastic change of relative humidity of the circumstance where they were put, which indicates that they have stable electrical conductivities.
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  • Ozone-Gas Treatment of Wool and Silk Fabrics
    Tomiji Wakida, Muncheul Lee, Jeong Hun Jeon, Takako Tokuyama, Hiroshig ...
    2004 Volume 60 Issue 7 Pages 213-219
    Published: 2004
    Released on J-STAGE: December 15, 2005
    DOIhttps://doi.org/10.2115/fiber.60.213
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    In previous papers, we reported that various cellulosic, wool and silk fabrics were treated with ammonia-gas with regard to the gas phase processing of the fabrics. In this paper, ozone-gas treatment of the wool and silk fabrics was carried out. The effect of the treatment on surface modification, dyeing property, wetting, and laundering shrinkage were evaluated. Although the physical surface was almost unchanged from the SEM observation, the O1s intensity by the ESCA analysis of both fibers in relation to surface modification increased, especially for wool. As the results, wetting property was improved remarkably despite of no change of the moisture regain and water absorption. Nevertheless, laundering shrinkage decreased apparently. Furthermore, apparent dyeing rate was accelerated considerably for wool, whereas equilibrium dye uptake was almost unchanged by the treatment. Mechanical property of the wool fabric was almost no change by the ozone-gas treatment, while those of the silk fabric became a little crisp.
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  • A New Approach to the Dynamics of Roller Draft Part 1: The Basic Scheme and an Application to a Model System
    Takashi Komori, Motoyoshi Itoh
    2004 Volume 60 Issue 7 Pages 220-229
    Published: 2004
    Released on J-STAGE: December 15, 2005
    DOIhttps://doi.org/10.2115/fiber.60.220
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    A theory of the dynamics of a sliver or roving under roller draft is presented in a general form based on the scheme of the fluid mechanics. The motion of a fiber bundle being drafted is described by three differential equations; one relates the local elongation of the bundle to the velocity distribution along the bundle, and the other two govern the conservation of mass and momentum. The momentum flux is composed of three terms due to mass flow, tension, and inter-fiber slip. The last term, the momentum transfer by interaction among fibers, has no trivial analogue in any of traditional theories proposed earlier, though indirectly it might connect with the force for pulling out fibers of the bundle. A hypothetical system simulated by a viscoelastic fluid flow is introduced as a standard model and its stationary motion is examined for illustrating how the basic scheme works, how the velocity and tension are formed along the bundle, how the drafting force depends on the system parameters, etc.
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  • Improvement of Mechanical Properties for Poly(L-lactic acid) Film through Drawing Process Optimization
    Jun Takagi, Tomoyuki Nemoto, Tatsuhiro Takahashi, Takashi Taniguchi, K ...
    2004 Volume 60 Issue 7 Pages 230-234
    Published: 2004
    Released on J-STAGE: December 15, 2005
    DOIhttps://doi.org/10.2115/fiber.60.230
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    The enhancement of tensile strength and elongation of poly(L-lactic acid) without using additives has been awaited to open new environmentally friendly markets. To improve the brittle mechanical properties of poly(L-lactic acid), we have investigated the effect of draw ratios and process temperatures on the mechanical properties. The results suggested that tensile strength linearly increased as a function of draw ratio, but elongation at break had a maximum value around draw ratio 2. It was found that the mechanical properties of the films were strongly affected by the draw ratio and not by the process temperature. Δn increased as a function of draw ratio up to 4 (the highest limit of the present test). These results allowed us to interpret that the mechanical properties reflected mainly molecular orientations in the amorphous regions, which were governed by the draw ratio.
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  • Changes in Surface Potential of Electrostatic Filter due to Dioctyl Phthalate (DOP) Aerosol Loading
    Kazushi Kimura, Mutsumi Kimura, Hirofusa Shirai
    2004 Volume 60 Issue 7 Pages 235-236
    Published: 2004
    Released on J-STAGE: December 15, 2005
    DOIhttps://doi.org/10.2115/fiber.60.235
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    Surface potential of electrostatic filter was investigated by dioctyl phthalate (DOP) aerosol loading. DOP aerosol was used for the loading test required by CFR part84 of the NIOSH standard. Surface potential greatly changed from filter-surface in the back-side due to DOP aerosol loading. Surface potential of back-side of the electrostatic filter changed in proportion to the airflow rate in the range of 5∼15cm/sec. DOP aerosol loading was caused by the disappearance of electrostatic charge of filter. The measurement of the surface potential by DOP aerosol loading can be also applied to the electrification material except for the filter.
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