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Volume 16 (1988)
- Issue 4 Pages 129-
- Issue 3 Pages 89-
- Issue 2 Pages 53-
- Issue 1 Pages 4-
Volume 16, Issue 3
Displaying 1-6 of 6 articles from this issue
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Tadao Kotaka, Hisashi Odani1988 Volume 16 Issue 3 Pages 89-90
Published: September 20, 1988
Released on J-STAGE: November 20, 2012
JOURNAL FREE ACCESSDownload PDF (171K) -
Shinzi HASHIZUME1988 Volume 16 Issue 3 Pages 91-98
Published: September 20, 1988
Released on J-STAGE: November 20, 2012
JOURNAL FREE ACCESSFluctuation of torque just after feeding natural rubber (NR) blocks into an oval-type twin-rotor mixer is discussed. A wedge-type model mixer was designed specially to simulate breaking behavior of NR between rotor and chamber. NR blocks of various thicknesses were contorted and finally broken in the model mixer. Two types of breaking phenomena were observed. One was instantaneous breaking of relatively thick blocks. The other was intermittent breaking of relatively thin blocks. These phenomena were mainly associated with the elastic deformation of the material. By considering these two types of breaking, the torque fluctuation measured during operation of the mixer was analyzed. It was clarified that the first peak of torque was originated from the first breaking of the block in the thickest state.View full abstractDownload PDF (1160K) -
Eiichi TAKATORI, Kunihiro OSAKI, Michio KURATA, Taisei HIRAYAMA1988 Volume 16 Issue 3 Pages 99-103
Published: September 20, 1988
Released on J-STAGE: November 20, 2012
JOURNAL FREE ACCESSViscoelastic properties were investigated for solutions of polystyrene with low moleccular weights, in which the polymer chains were not well entangled with each other. Molecular weights of the polymer were 5.0×104, 2.0× 105, 9.5×105, and 2.89×106, and the concentrations were adjusted so that the number of entanglements per chain, N, was equal to 1 or 2 for each molecular weight. The dynamic complex modulus was approximately in agreement with the prediction of the Rouse theory for the dilute polymer solution. Slight deviations observed at high frequencies were of the same type as were observed for very dilute solutions. The shear relaxation modulus, G(t, γ), decreased with increasing magunitude of shear, γ, but the degree of decrease was much smaller than that for well-entangled polymers with N>>1; the function h(γ) was larger than that for the well-entangled systems, where h(γ) is the long-time limiting value of the ratio G(t, γ)/G(t, 0). This result gives an experimental confirmation that the prediction on the nonlinear viscoelasticity of the tube model theory is good only for well-entangled polymers. Compared at the same value of N, the function h(γ) decreased with increasing molecular weight. Thus the number N was not the sole factor to determine the degree of nonlinearity when N was about 1.View full abstractDownload PDF (669K) -
Effects of Kind of Alkali and Concentration of Alkaline Aqueous Solution on Stress RelaxationTakato NAKANO1988 Volume 16 Issue 3 Pages 104-110
Published: September 20, 1988
Released on J-STAGE: November 20, 2012
JOURNAL FREE ACCESSStress relaxation behavior of wood treated with alkaline aqueous solution was investigated to clarify the efficiency of alkaline as a plasticizer of wood. Torsional stress relaxation of wood specimens treated with three kinds of alkali, namely, lithium hydroxide (LiOH), sodium hydroxide (NaOH) and potassium hydroxide (KOH), was measured in water at 30°C over a wide range of alkali concentration. Relaxation rigidity Gr at 104 sec decreased remarkably in the concentration of 5-10% of the NaOH solution, while the corresponding decrease of Gr treated with the KOH solution occurred at somewhat higher concentrations compared with those of NaOH. The coefficient of longitudinal shrinkage of the treated wood under water-saturated condition showed similar dependence on alkali concentration. Furthermore, a peak in relaxation spectrum of the treated wood shifted toward shoter time range above the concentration of 10% for NaOH and above 18% for KOH. It has been inferred from the results that slipping and loosing motions of the microfibrils in the wood cell being shrinked by the alkali treatment give rise to the stress relaxation phenomena. The wood plasticized by the present method has been found to be easily bent and molded, which indicates the versatility of the present method.View full abstractDownload PDF (1148K) -
Toshiro MASUDA, Masaoki TAKAHASHI, Hideki OHNO, Lin LI1988 Volume 16 Issue 3 Pages 111-116
Published: September 20, 1988
Released on J-STAGE: November 20, 2012
JOURNAL FREE ACCESSA Meissner-type uniaxial extensional rheometer has been constructed. The characteristic features of this rheometer are the following :(1) The distance between two rotary clamps has been decreased to 12 cm, and the measurement can be done with a small amount of sample.(2) The rotary clamps and the motors are equipped on the top cover in order to make it very easy to install and remove samples.(3) The sample in extension can always be seen through the glass windows at both sides of the oil bath. The elongational flow behavior for various polymer melts (polystyrenes with narrow and broad molecular weight distributions, low-density polyethylene, high-density polyethylene, and polypropylene) was measured using this rheometer. It has been confirmed that this extensional rheometer can be used to obtain a homogeneous, uniaxial elongational deformation under a constant strain rate.View full abstractDownload PDF (835K) -
Lin Li, Toshiro MASUDA, Masaoki TAKAHASHI, Hideki OHNO1988 Volume 16 Issue 3 Pages 117-124
Published: September 20, 1988
Released on J-STAGE: November 20, 2012
JOURNAL FREE ACCESSThe elongational flow behavior of various polymer melts has been measured using a new Meissner-type uniaxial extensional rheometer. The following results are obtained for polystyrene melts :(1) When the strain rate ε is sufficiently low, transient elongational viscosity function ηE+(t) agress with 3η+(t), where η+(t) is the corresponding function in shear. ηE+(t, ε) at high ε still agrees with 3η+(t) when the strain is smaller than a critical value. At large strains, ηE+(t, ε) becomes larger than 3η+(t) and approaches asymptotically to a steady value.(2) The steady value of ηE+ for a broad-distribution polystyrene is somewhat larger than 3η0, where η0, is the zero-shear viscosity. The steady elongational viscosity ηE(ε) of a narrow-distribution polystyrene is equal to 3η0, in the strain-rate region where the shear viscosity ε(γ) decreases with γ, while it begins to decrease with ε at high ε.(3) The nonlinear function ΛηNL(=ηE+(t, ε)/ηE+(t)) becomes more strongly dependent on strain ε(=εt) with increasing strain rate. For a low-density polyethylene melt, ηE+(t, ε)(or elongational stress σ) at low ε increases smoothly with time t (or ε), approaching asymptotically to a steady value. ηE+ (or σ) at high ε increases in two stages with t (or ε). Finally, it has been emphasized that the measurement of ε through observation of the sample diameter is very important, especially for polyolefin samples.View full abstractDownload PDF (1006K)
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