NIPPON GOMU KYOKAISHI
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Volume 42, Issue 4
Displaying 1-8 of 8 articles from this issue
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  • ON THE PHYSICAL PROPERTIES AND THE STIFFNESS OF RUBBER
    T. Kotani, M. Kawashima
    1969 Volume 42 Issue 4 Pages 249-253
    Published: 1969
    Released on J-STAGE: April 16, 2008
    DOIhttps://doi.org/10.2324/gomu.42.249
    JOURNAL FREE ACCESS
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    Molecular chain of rubber may be stiffened by the steric hindrance, the rotational hindrance around C-C bond, the intermolecular interaction, the excusive volume effect, and so on. The relative value of the stiffness of cross-linked rubber is assumed from glass temperature, cohesion energy donsity, the structural model and so on. However, the method to assume the stiffness quantitatively is not established for vulcanized rubber. In this report, a method to assume the stiffness quantitatively was proposed using stress-birefringencial measurement of rubber.
    If the molecular chain of rubber is stiffer, the distance between crosslinks will be larger and then the critical elongation will be smaller. To discuss these correlations, a method to assume the stiffness of vulcanized rubber is described using stress-birefringence of rubber, and some equations were proposed for the some physical properties and stiffness of rubber.
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  • THE CRITICAL ELONGATION AND THE MOLECULAR WEIGHT BETWEEN CROSS-LINKS OF RUBBER
    S. Suzuki, T. Tosaki, M. Kawashima, T. Kotani, S. Kimura, K. Mizushima
    1969 Volume 42 Issue 4 Pages 254-259
    Published: 1969
    Released on J-STAGE: April 16, 2008
    DOIhttps://doi.org/10.2324/gomu.42.254
    JOURNAL FREE ACCESS
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    The maximum elongation was always recognized at a temperature, Tmax when the elongation at break was measured at various temperatures from -100° to 150°C. Taking the maximum elongation as the critical elongation, αc, the critical elongation was found to relate linearly with the inverse of the square root of the cross-linking density, ν-1/2, and with the square root of the molecular weight of the chain between cross-links, Mc1/2, in the same cure system and the same polymer. The temperature, Tmax, at which the maximum elongation was observed, was lowered linearly with the increase of the cross-linking density, ν. The gradient of the slope of Tmax to ν changed by the cure system and the polymer. The glass temperature of these samples were heightened with the cross-linking density.
    Thinking the molecular chain to be elongated enough at Tmax, the number of the statistical segment was assumed from the inverse Langevin function and from the critical elongation using αc=n1/2. The number of the monomeric units in the chain was calculated from Mc/M, where M is the molecular weight of monomeric unit.
    Comparing these results, it was concluded that i) the molecular chain of rubber was assumed to be broken down after enough elongation at Tmax, ii) the number of the segment can be assumed from the critical elongation and from the stress-strain curve using the inverse Langevin function and iii) the value of αc/(Mc/M)1/2 may be taken as an index of the stiffness of the chain.
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  • THE CRITICAL ELONGATION AND THE STIFFNESS OF RUBBER
    T. Kotani, M. Kawashima, S. Suzuki, M. Nakao
    1969 Volume 42 Issue 4 Pages 260-264
    Published: 1969
    Released on J-STAGE: April 16, 2008
    DOIhttps://doi.org/10.2324/gomu.42.260
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    Taking the number of the segment as n, Flory et al., showed theoretically that the critical elongation, αc becomes equal to the square root of the number, n1/2. However, the method to assume the number of the segment is not established, then the experimental support is not obtained. It is also examined few that the molecular chain sustains to how much elongation.
    In this report, the elongation at break was measured at various temperatures from -100°C to 150°C and the maximum elongation was taken as the critical elongation. The molecular weight of the chain between cross-links Mc was measured from equlibrium swelling and the stiffness of the chain was assumed from the stress-birefringence using the equation for the relation. From these results, the number of the segment between cross-links was assumed for the various rubbers.
    These results suggest that 1) the critical elongation relates linearly with the square root of the number of the segment, which was assumed from the stress-birefringencial method, 2)the molecular chain of rubber was oriented enough at the critical elongation, and 3) the critical elongation is calculated to be K(Mc/MZ)1/2, where M and Z are the molecular weight of monomeric unit of the chain and the stiffness measured from the stress-birefringence, respectively. K was about 1.2 for various rubbers.
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  • A STUDY ON HEAT HISTORY OF ORGANIC ACCELERATORS IN RUBBER STOCK (BR BASE)
    I. Imase
    1969 Volume 42 Issue 4 Pages 265-278
    Published: 1969
    Released on J-STAGE: April 16, 2008
    DOIhttps://doi.org/10.2324/gomu.42.265
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    The test was carried out to compare and to see how the properties of un-cured compounds and vulcanisates vary under the influence of heat treatment at 100°C and 150°C respectively for 30 minutes of BR stocks mixed at normal temperature (below 70°C) that were blended with compounding ingredients including twelve kinds of organic accelerators but excluding sulfur.
    As a result the accelerators in most cases were found unstable to the heat treatment. Among those that becomes liable to scorch are included CZ (N-cyclohexyl-2-benzothiazolesulfenamide), MSA (N-oxydiethylene benzothiazole-2-sulfenamide), DT (Di-0-tolyl guanidine) and among those in which the scorch time gradually extends are D (Diphenyl guanidine), TET (Tetraethylthiuram disulfide), TRA (Dipentamethylenethiuramtetrasulfide), EZ (Zn-diethyl dithiocarbamate) and PX(Zn-ethyl-phenyl dithiocarbamate). Those that do not vary under 100°C, but will extend the scorch time under 150°C are M (2-mercaptobenzothiazole), DM (Benzothiazyldisulfide), TT (Tetramethylthiuram disulfide) and TS (Tetramethylthiuram monosulfide).
    It was also found that the stability to curing was good in DT which was less variable. Those that are comparatively good in this uspect are CZ, MSA, but, M, DM, D, TT, TS, TET would remarkably prevent curing function under 150°C while TRA, PX were found extremely unstable and would retard the cure under 100°C treatment.
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  • [title in Japanese]
    [in Japanese]
    1969 Volume 42 Issue 4 Pages 279-294
    Published: 1969
    Released on J-STAGE: April 16, 2008
    DOIhttps://doi.org/10.2324/gomu.42.279
    JOURNAL FREE ACCESS
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  • [title in Japanese]
    [in Japanese]
    1969 Volume 42 Issue 4 Pages 295-304
    Published: 1969
    Released on J-STAGE: April 16, 2008
    DOIhttps://doi.org/10.2324/gomu.42.295
    JOURNAL FREE ACCESS
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  • [title in Japanese]
    [in Japanese]
    1969 Volume 42 Issue 4 Pages 305-306
    Published: 1969
    Released on J-STAGE: April 16, 2008
    DOIhttps://doi.org/10.2324/gomu.42.305
    JOURNAL FREE ACCESS
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  • [title in Japanese]
    [in Japanese]
    1969 Volume 42 Issue 4 Pages 307-308
    Published: 1969
    Released on J-STAGE: April 16, 2008
    DOIhttps://doi.org/10.2324/gomu.42.307
    JOURNAL RESTRICTED ACCESS
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