Nihon Reoroji Gakkaishi
Online ISSN : 2186-4586
Print ISSN : 0387-1533
ISSN-L : 0387-1533
Volume 7, Issue 1
Displaying 1-8 of 8 articles from this issue
  • Yutaka MIYAHARA, Michio KURATA
    1979 Volume 7 Issue 1 Pages 1-2
    Published: March 30, 1979
    Released on J-STAGE: November 20, 2012
    JOURNAL FREE ACCESS
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  • Norio NEMOTO
    1979 Volume 7 Issue 1 Pages 3-14
    Published: March 30, 1979
    Released on J-STAGE: November 20, 2012
    JOURNAL FREE ACCESS
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  • Takuii YAMAGUCHI, Hiroshi KIMURA
    1979 Volume 7 Issue 1 Pages 15-19
    Published: March 30, 1979
    Released on J-STAGE: November 20, 2012
    JOURNAL FREE ACCESS
    For nonlinear viscoelastic materials, no universal method has been obtained to derive the relaxation modulus from the creep compliance or vice versa. We give here a method for converting the relaxation modulus E n (t, ε) to the creep compliance Jn (t, σ) in uniaxial deformation based on the constitutive model of Schapery. Here t, ε, and σ are the time, strain, and stress, respectively. It is assumed that En (t, ε) is proportional to some power of time, t-β, where β is a constant (power law model). Mathematical procedure of conversion is discussed for two types of strain dependence of En (t,ε), the Nutting model and exponential model: En (t,ε) is assumed to be proportional to ε for the former and to exp (-rε) for the latter, where α and γ are constants. For the Nutting model, Jn (t, σ) can be analytically derived from En (t, ε), and it becomes proportional to σα/(1-α)tβ/(1-α). For the exponential model, Jn(t, σ) can be obtained as an approximate solution of a nonlinear integral equation. The derived rate of creep depends on the model adopted to represent the strain dependence of En(t, ε): Jn (t, σ) derived from the exponential model increases faster than that from the Nutting model. The observed creep compliance for a polyethylene is in rough agreement with the prediction of either of the models in the ranges of strain, ε≤0.03 for the Nutting model and ε≤0.05 for the exponential model, where each model is applicable to the experimental data of En(t,ε).
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  • Yuji AOKI
    1979 Volume 7 Issue 1 Pages 20-26
    Published: March 30, 1979
    Released on J-STAGE: November 20, 2012
    JOURNAL FREE ACCESS
    The dynamic viscoelastic properties of ABS resins were measured in the molten state with a rotating cylinder type rheometer over wide ranges of temperature and frequency. Two series of resins with rubber contents, 0, 10, 20, and 30 wt%, were prepared by blending an AS copolymer with two kinds of ABS resins having different ratios of grafted AS copolymer to butadiene rubber. The main results are summarized as follows. 1) At high frequencies (rubbery zone), the magnitudes of the storage shear modulus (G) and the loss shear modulus (G) are independent of the rubber content, but rubbery plateau shifts to low frequency side as the rubber content rises. 2) At low frequencies (terminal zone), G and G increase progressively with increasing rubber content in each series. G does not depend on the kind of ABS resins but on the gel (rubber+grafted AS copolymer) content. On the other hand, G depends on the kind of ABS resins: The resins with higher grafted AS ratio exhibit the “second plateau” of G, and the others do not. 3) Time-temperature superposition principle can be applied in the ABS resins. The temperature dependence of shift factors is expressed by the WLF-type equation. The free volume of ABS resins decreases slightly with increasing rubber content.
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  • Masayuki KASAJIMA, Akira SUGANUMA, Daizo KUNII, Katsuhiko ITO
    1979 Volume 7 Issue 1 Pages 27-33
    Published: March 30, 1979
    Released on J-STAGE: November 20, 2012
    JOURNAL FREE ACCESS
    When two different polymers are mechanically blended, the flow curve of the composite melt does not always lie in between the curves for the component polymers. In order to find the condition for this phenomenon to occur, we measured the flow curves of blends of a polystyrene (PS) and a high density polyethylene (HDPE) with a Thixotrometer. Four samples of PS of various fluidities were examined. The fluidity of HDPE was higher than any PS samples at the temperature of measurements, 200°C.
    When the fluidity of PS was very low and much apart from that of HDPE, the flow curves for the blends lay between those of PS and HDPE at any blend ratio. As the fluidity of PS increased and approached that of HDPE, the flow curve for the blend of high PS content, i.e., 0.75, became to intersect that for the PS; the blend exhibited a fluidity lower than even the component PS at low rates of shear. In the case of the PS of the highest fluidity, the blend of high PS content exhibited fluidity lower than the PS over the whole range of rate of shear studied. These results were discussed in terms of a proposed phenomenological blending law.
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  • Shoichiro YANO, Mikio MURAYAMA
    1979 Volume 7 Issue 1 Pages 34-41
    Published: March 30, 1979
    Released on J-STAGE: November 20, 2012
    JOURNAL FREE ACCESS
    Photodegradation of nylon 6 was studied by dynamic viscoelastic measurements. Dynamic viscoelastic properties of weathering nylon 6 were also measured. In order to investigate the effect of wavelength of the irradiation, spectrally dispersed ultraviolet light between 219 and 415nm from 2kW xenon lamp were irradiated on nylon 6 film and changes in the dynamic modulus E′ were measured at each avelength. The values of E′ were increased by the irradiation at wavelength below about 300nm. From the results along with those X-ray diffractometry, viscosity measurements, and solubility tests in m-cresol, it was suggested that the increase in E′ resulted from the crosslinking reaction. Variation of E′ during irradiation at 253.7nm was also measured using a low pressure mercury lamp. It was found that E′ decreased rapidly in the region of short times reflecting the occurence of scission reactions, then increased at longer times, and reached a certain equilibrium value. The increase of E′ at longer times was interpreted as due to the crosslinking reactions. The change in E′ with time was well expressed by the following equation: Et′=E0′exp(-k1t)+E′[1-exp(-k2t)], where Et′ is the E at time t, E0′ is that at t=0, E′∞is the equilibrium value of the E′, and k1 and k2 are the rate constants.
    Changes of E′ and density during weathering at Hokkaido and Choshi were measured. Both E′ and density were increased with weathering time. The changes in X-ray diffraction patterns have revealed the result of the transition of the crystal structure of nylon 6 from the β form to the α form, which was caused by absorption of water coming from rainfall. The values of [η] decreased steadily with exposure time. It was inferred that these were caused by a scission reaction due to the sunlight, a kind of low energy ultraviolet rays with wavelength longer than about 300nm. In the loss tangent versus temperature plots of the weathering nylon 6, α, β, γ relaxations were observed. Also an additional dispersion was found at about 30°C, which was in between the α and β relaxations. The dispersion was assigned to the shifted α relaxation due to plasticizing effect of absorbed water. In the temperature range between -20 and -120°C, E′ of weathering sample was higher than that of dry nylon 6 (α form). This was also inferred as related to the absorbed water. However, E′ of dry nylon 6 of α structure was higher than that of weathering sample at temperatures above about 20°C.
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  • Kaoru SHIMAMURA, Syozo MURAKAMI, Masaki TSUJI, Ken-ichi KATAYAMA
    1979 Volume 7 Issue 1 Pages 42-46
    Published: March 30, 1979
    Released on J-STAGE: November 20, 2012
    JOURNAL FREE ACCESS
    Internal structure exposed by fracturing the necking part of drawn polyethylene has been examined by a scanning electron microscope and the deformation mechanism of spherulites has been clarified. Drawing of unoriented specimens at 100°C gave a structure composed of macrofibrils whose diameters were strongly dependent on the period of lamellar twisting in the original spherulites. On the other hand, in the specimens drawn at 0°C, many slender regions of complex structure existed among macrofibrils; the structure, about 1~2 μm diameter, stems from the lamellae perpendicular to the draw direction.
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  • Shigeki MITAKU, Toshiya OHTSUKI, Koji OKANO
    1979 Volume 7 Issue 1 Pages 47-49
    Published: March 30, 1979
    Released on J-STAGE: November 20, 2012
    JOURNAL FREE ACCESS
    Steady flow properties of the ordered monodisperse polystyrene latex have been measured. The ordered latex has a yield stress of about 1 dyne/cm2 and the yield stress σ is related to the rigidity G as σ=1.7×10-3G. These facts suggest that the ordered monodisperse latex is a “crystal” which undergoes a plastic deformation by the same mechanism as the ordinary crystals. The salt concentration dependence of the steady flow viscosity in the disordered latex is also discussed.
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