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Volume 24 (1996)
- Issue 4 Pages 149-
- Issue 3 Pages 105-
- Issue 2 Pages 57-
- Issue 1 Pages 5-
Volume 24, Issue 2
Displaying 1-6 of 6 articles from this issue
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Young Sil LEE, O Ok PARK1996 Volume 24 Issue 2 Pages 57-62
Published: June 15, 1996
Released on J-STAGE: November 20, 2012
JOURNAL FREE ACCESSThe stead0y shear and viscoelastic behaviors of polyaniline suspension in the mineral oil subject to an electric field were studied experimentally using a Couette cell type rheometer. The dynamic yield stress determined from the plateau stress in the range of low shear rate was evaluated as a function of the applied field and particle volume fraction. The resultant yield stress is linearly increased with volume fraction and E3/2. The storage shear modulus and loss modulus have been measured using small amplitude forced oscillatory dynamic test as functions of strain amplitude, driving frequency, and the applied field strength. The linear viscoelastic region was found to be as below 0.01 of strain amplitude by performing the amplitude sweep test. The storage and loss moduli were strongly dependent upon strain amplitude while those were nearly independent of the driving frequency for the range of 10-1~102rad/s.View full abstractDownload PDF (846K) -
A. OUDJEHANE, M. FUSHITANI1996 Volume 24 Issue 2 Pages 63-66
Published: June 15, 1996
Released on J-STAGE: November 20, 2012
JOURNAL FREE ACCESSOn account of their oriented and heterogeneous structure woods are anisotropic but also porous and thus sensitive to any variation of humidity. Under permanent solicitations (deformations or heat and mass transfer), woods generally show a high degree of directionality and their internal structures evolve and sometimes change. We have observed the evolution of the anisotropy of the structure of oakwood regarding to its response under thermomechanical solicitations: a drying set and triaxial tests.View full abstractDownload PDF (536K) -
Yoshiaki Kanoh, Takayuki Shibata, Takafumi Nishimura, Hiromoto Usui, T ...1996 Volume 24 Issue 2 Pages 67-73
Published: June 15, 1996
Released on J-STAGE: November 20, 2012
JOURNAL FREE ACCESSThree different polymers, a high density polyethylene (HDPE), a polypropylene(PP), and a polycarbonate(PC), were subjected to a flow visualization study in two rectangular channels with different width-to-height ratios, and the flow velocity profile in the channel was determined as a function of polymer melt temperature, channel wall temperature, and mass flow rate, as well as the pressure applied to the polymer melt in the channel and the geometry of the channel. The flow velocity data, which were measured by using a particle tracer technique and accumulated in a computer, were analyzed by a CAE program “POLYFLOW” developed on the basis of Bird-Carreau model to simulate the flow velocity curves in both vertical and horizontal longitudinal sections which involve the central axis of the channel. The extrapolation of the flow velocity curves to the inner wall surface allowed to estimate the contribution of slip flow on the channel wall (Vs) to the total flow velocity. When HDPE was subjected to the channel flow, the Vs increased with increasing mass flow rate, temperature of running polymer, and temperature of channel wall, but decreased with increasing pressure applied to the melt. More pronounced effects of the melt temperature and the mass flow rate was found on the wall slip phenomena for both PP and PC.View full abstractDownload PDF (1096K) -
Kiyofumi MATSUOKA, Guy C. BERRY1996 Volume 24 Issue 2 Pages 75-85
Published: June 15, 1996
Released on J-STAGE: November 20, 2012
JOURNAL FREE ACCESSThe rheological behavior on shear flow of aligned nematic solutions of rodlik Poly(1,4-phenylene-2,6-enzobisthiazole), PBZT, is discussed. The results show that the initial transient response to the onset of flow reflects the curvature elasticity, with minimal distortion of the director field near the shear surfaces. With increasing strain, the behavior is complicated by rotation of the rodlike chains out of the shear plane, causing, for example, a loss of conoscopic interference figures, and a decrease in the anisotropy of the fluorescence emitted from the first micron thickness near the shear surface. Line-defects appear with continued shear flow.View full abstractDownload PDF (3099K) -
Shin'ya YOSHIOKA, Tomomi SAKAMOTO, Yukuo NANZAI1996 Volume 24 Issue 2 Pages 87-91
Published: June 15, 1996
Released on J-STAGE: November 20, 2012
JOURNAL FREE ACCESSThe concept of shear-induced structural change, which has been quite successful in interpreting nonlinear viscoelasticity of amorphous polymers in the glassy region, was extendedly examined for nonlinearity in large deformation behaviors of polymethyl methacrylate (PMMA) in the rubbery temperature range. At temperatures above the glass transition temperature, Tg, the PMMA specimens were stretched at high strain rates to various large strains and then subjected to stress relaxation. Even at temperatures much higher than Tg, a well-defined yield point was observed at a strain of around 0.1 at relatively higher strain rates. The appearance of the yield point was always accompanied by a substantial reduction of the relaxation modulus at short times in the glass-to-rubber transition range. This reduction gives evidence of facilitated rearrangement of chain segments probably due to the shear-induced structural change independently of chain disentanglements. Hence, it is concluded that the shear-induced structural change is likely to occur also in the rubbery liquid state of the polymer system, and the mechanism of the yield observed in the rubbery range can essentially be identified with that of the yield in the glassy range.View full abstractDownload PDF (860K) -
M. KUDO, Y. TSUNEOKA, K. IWAKURA, T. MASUKO1996 Volume 24 Issue 2 Pages 93-98
Published: June 15, 1996
Released on J-STAGE: November 20, 2012
JOURNAL FREE ACCESSDynamic viscoelasticities of disperse systems composed of hexagonally shaped Ba-Ferrite fine particles and a poly (vinyl chloride)copolymer solution have been investigated in terms of the pigment volume fraction, φPL. In the frequency dependency of the dynamic characteristics, a second plateau was observed both in G′ and G″ spectra, the value of which increased with increasing φPL. The absolute values of the complex shearing stress corresponding to the magnitudes of the respective plateaus showed linear relationships with the yield stresses and the floc volume fractions, φF, obtained from the steady flow measurements. These relation-ships suggest that the yield stress is closely related to the second plateau result due to their flocculated structure. The network structures three-dimensionally linked among flocculated particles grow in the suspension and the network density increases with increasing φF. The relaxation spectra obtained by the zero-th ap-proximation indicates that a relaxation mechanism with long relaxation time exists in this system.View full abstractDownload PDF (775K)
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