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Predecessor
Volume 60, Issue 9
Displaying 1-10 of 10 articles from this issue
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[in Japanese]1987 Volume 60 Issue 9 Pages 485-495
Published: 1987
Released on J-STAGE: July 09, 2007
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[in Japanese]1987 Volume 60 Issue 9 Pages 496-502
Published: 1987
Released on J-STAGE: July 09, 2007
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[in Japanese]1987 Volume 60 Issue 9 Pages 503-512
Published: 1987
Released on J-STAGE: July 09, 2007
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[in Japanese]1987 Volume 60 Issue 9 Pages 513-517
Published: 1987
Released on J-STAGE: July 09, 2007
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[in Japanese]1987 Volume 60 Issue 9 Pages 518-520
Published: 1987
Released on J-STAGE: July 09, 2007
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[in Japanese]1987 Volume 60 Issue 9 Pages 521-523
Published: 1987
Released on J-STAGE: July 09, 2007
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Norio TSUBOKAWA, Kazuhide KITA, Yasuo SONE1987 Volume 60 Issue 9 Pages 524-530
Published: 1987
Released on J-STAGE: July 09, 2007
JOURNAL FREE ACCESSIn the presence of polystyrene-grafted (CB-PS), poly (methyl methacrylate)-grafted (CB-PMMA), polyester-grafted (CB-PEs), and poly (β-alanine)-grafted carbon black (CB-PAL), the anionic polymerization of styrene initiated by n-butyllithium (BuLi) was investigated. A marked retardation of the polymerization was observed in the presence of untreated carbon black because BuLi reacts preferentially with oxygen containing groups on carbon black such as phenolic hydroxyl, quinonic oxygen, and carboxyl groups. The retardation by carbon black did not disappear even if the oxygen containing groups were blocked by the treatment with several reagents. On the contrary, in the presence of CB-PS, CB-PAL, and CB-PMMA, the retardation of carbon black was weakened gradually with an increase in the grafting ratio of polymer. In particular, in the presence of CB-PMMA (grafting ratio=76.1%), the retardation disappeared almost completely. These phenomenon suggests that the functional groups on carbon black surface were blocked by the grafted polymer chain. The ability of grafted polymer chain for the blocking of the surface was found to increase in the following order: CB-PS_??_CB-PAL<CB-PMMA. On the other hand, the ability of retardation of CB-PEs increased with an increase in the grafting ratio. This may be due to the effect of a terminal group of the grafted polymer chain.View full abstractDownload PDF (780K) -
Iwao YAMASHITA, Noboru YAMAMOTO, Kazuko HAYASHI1987 Volume 60 Issue 9 Pages 531-537
Published: 1987
Released on J-STAGE: July 09, 2007
JOURNAL FREE ACCESSAn elastomer used in artificial heart is required to have antithrombogenicity and long-term durability. It has previously been reported that a series of polyurethaneureas (DPs) produced from triblock copolyether (PEO-PPO-PEO), 4, 4′-diphenylmethane diisocyanate and ethylene diamine, exhibit excellent antithrombogenicity. The long-term fatigue test of several DP specimens was carried out by repeating uniaxial tensile deformation in physiological saline solution at 37°C under the following conditions: strain amplitude, ±10% under 50% strain level; frequency, 5Hz; number of cycles, 3-7×107. No failure was observed for all specimen during the test. The maximum cycles 7×107 correspond to the pulsation cycles for about 2 years of natural heart at rest. The dynamic moduli were almost constant during the test, except for the steep decay at the early stage. The fatigued specimens generally tended to harden. However, the modulus at lower strain decreased for the fatigued specimens compared to the original. These changes in tensile propertes were discussed from the Mooney-Rivlin plots for the stress-strain curves. Further, the fatigued specimens exibited anisotropic swelling in dichloroethane. These results can be interpreted in terms of a strain-induced orientation and a stress-softening during the test.View full abstractDownload PDF (826K) -
Kunihiko FUJIMOTO, Shin TOKUI1987 Volume 60 Issue 9 Pages 538-545
Published: 1987
Released on J-STAGE: July 09, 2007
JOURNAL FREE ACCESSIn this paper, making use of the formula for rate process in formation of heterogeneous structures through three-dimensionally stressed fatigue in a previous paper, the relation of fatigue times in which heterogeneous structures caused through random-stressed fatigue and those through step-stressed fatigue become equal is discussed mathematically and experimentally. The results are as follows:
(1) The relation of fatigue times in which heterogeneous structures caused through step-stressed fatigue (by combination of arbitrary stress σi, arbitrary times _??_tij, arbitrary temperature Ti) and those through constant stressed fatigue (basic stress σ0, basic temperature T0=aiTi) become equal is given by the following formula:
t(σ0)=∑<i>∑<j>exp[1/k•T0{U0(1-ai)+α(aiσ2i-σ20)}]•_??_tij
(2) Fatigue curve for random-stressed fatigue (average stress σ, dispersion S2) can be expressed by setting the fatigue time t(σ) of constant stressed fatigue 1/a times larger, where in
a=1/√<1-(2α•s2/k•Tran)>•exp{α•σ2/k•Tran(2α•s2/k•Tran-2α•s2)}
and U0 is activation energy, α is transformation parameter and k is Boltzmann′s constant.View full abstractDownload PDF (699K) -
[in Japanese]1987 Volume 60 Issue 9 Pages 546-547
Published: 1987
Released on J-STAGE: July 09, 2007
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