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Volume 30 (2002)
- Issue 5 Pages 231-
- Issue 4 Pages 165-
- Issue 3 Pages 121-
- Issue 2 Pages 83-
- Issue 1 Pages 3-
Volume 30, Issue 4
Displaying 1-7 of 7 articles from this issue
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Original Articles
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K OsakiArticle type: Article
2002 Volume 30 Issue 4 Pages 165-172
Published: 2002
Released on J-STAGE: July 10, 2003
JOURNAL FREE ACCESSSome of the "well-known" features in polymer rheology are inconsistent with recent data. (1) Complex modulus of non-entangled polymer solutions cannot be described with the Rouse-Zimm equation with any choice of parameters. An extra term with a single relaxation time removes the discrepancy and also accounts for shear thinning behavior in steady flow. (2) Values of the longest Rouse relaxation time, τR, derived from viscosity are much higher than those from dynamic modulus at high frequencies, which are consistent with retraction rate of extended chain estimated from stress overshoot. (3) Entanglement molecular weight, Me, evaluated from entanglement modulus for solutions in Θ solvent is equal to that in good solvent. Me values derived from viscosity-molecular weight relation vary with solvent quality. Parameters such as M e and τR from viscosity should be used with care; evaluation method is based on behavior of non-entangled systems, which may not represent behavior of entangled systems.View full abstractDownload PDF (388K) -
Yoshio Shirasaki, Ikuo Aida, Tetsuya Tateishi, Kazuhiko HayashiArticle type: Article
2002 Volume 30 Issue 4 Pages 173-178
Published: 2002
Released on J-STAGE: July 10, 2003
JOURNAL FREE ACCESSAging effect on the mechanical properties and bone density of the rat cervical and lumber spine were evaluated from young to old specimens. The dynamic viscoelastic properties were measured by a viscoelastic spectrometer. The static test was performed with an Instron-type universal testing machine. We examined dynamic stiffness, tanδ, fracture load, ultimate strength, and deformation energy of the cervical and lumber spine over several period of the time. Bone mineral content was measured by dual X-ray absorptiometry at the femoral diaphysis, femoral distal and lumber 3(L3). The dynamic stiffness and tanδ without the soft tissue around lumber spine indicated a second order polynomial function of age, but cervical spine showed no clear trend with age. Fracture load of the cervical and lumber spine indicated a second order polynomial function of age. We also found linear relations between the mechanical properties and density of bone.View full abstractDownload PDF (592K) -
Takeaki Tsuda, Tomiichi Hasegawa, Takatune NarumiArticle type: Article
2002 Volume 30 Issue 4 Pages 179-185
Published: 2002
Released on J-STAGE: July 10, 2003
JOURNAL FREE ACCESSOne-dimensional flow model for non-Newtonian fluids in a dual cavity slot die is presented. The viscosity of non-Newtonian fluids is treated as the Ellis model. The conservation equations of mass and momentum in a dual-cavity slot die are one-dimensionally simplified by assuming an appropriate mean flow over the cross section of the flow. The flow field in the slot is assumed to be fully developed. The equations of flow for the cavity and the slot are derived separately and then coupled. We use a finite difference method to solve these governing equations. Using this model, we find that the location and the cross-section area of a secondary cavity have large effects on the distribution of outlet flow. It is concluded that the dual cavity die can effectively reduce the flow non-uniformity.View full abstractDownload PDF (799K) -
H. S.Yang , G. J.Nam , H. S.Kim , J. W.LeeArticle type: Article
2002 Volume 30 Issue 4 Pages 187-193
Published: 2002
Released on J-STAGE: July 10, 2003
JOURNAL FREE ACCESSThe relationships between the interfacial tension and rheological properties in LDPE/PS blend system have been investigated. The block copolymer SEBS has been used as a compatibilizer. The interfacial tension was measured by the breaking thread method. Its value of LDPE/PS was 5.52dyne/cm and it is decreased rapidly with SEBS contents to 1wt% and then level off to a saturation value of 3.1dyne/cm. From the oscillatory shear deformation test, G' of the LDPE/PS blend increased with the LDPE contents at low frequencies due to the interfacial tension while G" showed similar behavior with that of pure LDPE and PS. The emulsion model considering the interfacial tension and droplet size in blends could predict the dynamic storage and loss modulus in reasonable range. Gramespacher and Meissner's emulsion model was used in this study. When the SEBS 1wt% was added to the LDPE/PS blend as a compatiblizer, there was a slight drop of storage modulus at low frequency ranges. As the SEBS contents increased over 3wt%, however, there was a dramatic increase of storage modulus. It was because of the saturation of the interfacial and micelle formation. As the SEBS content increased, the droplet size of LDPE decreased and the amount of micelle increased at the LDPE/PS interface.View full abstractDownload PDF (734K) -
M Yamanoi, M Funahashi, S Tanoue, Y IemotoArticle type: Article
2002 Volume 30 Issue 4 Pages 195-202
Published: 2002
Released on J-STAGE: July 10, 2003
JOURNAL FREE ACCESSA ferrofluid, which is a suspension of magnetic particles in matrix fluid, is known as one of the intelligent fluids. The particles form clusters under the magnetic fields. As a result, the rheological properties are very complex. The main cause is a lot of types of aggregate structures. In this study, we have studied the relation between rheological properties and aggregate structures for oscillatory shear flows by Stokesian dynamics simulations. The following results are obtained. The aggregation is of layered structures when magnetic forces are dominant, while it is of the inclined structures when shear forces are dominant. In the latter case, the phase angle of the stress due to the magnetic force is delayed relative to that of the strain, and the magnetic force has a negative contribution to the viscosity. It is found that the origin of this negative viscosity contribution is the interactions between particles in the same cluster in the low strain region, and the interactions between clusters in the large strain region.View full abstractDownload PDF (717K) -
Hiroshi Yamaguchi, Naoya OharaArticle type: Article
2002 Volume 30 Issue 4 Pages 203-208
Published: 2002
Released on J-STAGE: July 10, 2003
JOURNAL FREE ACCESSFlow of viscoelastic fluid contained between a stationary inner half-sphere and a rotating outer sphere was studied experimentally. Measurements of the stationary torque and thrust of the inner half-sphere were made. The situation of uniquely appearing flow for viscoelastic fluids were obtained by flow visualization. The measurement results of torque and thrust showed that Reynolds number and a gap ratio influenced the torque characteristics substantially, while the thrust is much effected by the elastics effect. Resultant experiment data was arranged by empirical formula for given geometric configuration, using the Deborah number together with the generalized Reynolds number.View full abstractDownload PDF (963K) -
Hiromasa Adachi, Teruo HasegawaArticle type: Article
2002 Volume 30 Issue 4 Pages 209-213
Published: 2002
Released on J-STAGE: July 10, 2003
JOURNAL FREE ACCESSThe elastic modulus of unidirectional carbon fiber reinforced plastics (CFRP) was investigated by mechanical tests and analysis using finite element method (FEM). The mechanical tests are three points bending tests and tension tests. The analysis was examined by micro model and macro model. On the micro model, the 3-dimensional finite element method program created in consideration of the anisotropy of carbon fiber and the isotropy of matrix was applied to the hexagonal array model. On the macro model, the 2-dimensional finite element method program created in consideration of the anisotropy of CFRP was applied to the plane stress model using the triangle element. Consequently, it was found that the calculated data of the micro and macro model was larger than the experimental data. It was considered that the carbon fiber in the matrix was wound. Furthermore, the calculated data of the macro model in consideration of the angle θ of the direction of the carbon fiber was found to be in a reasonable agreement with the experimental data of the tension tests in case of θ = 0 ˜18° decided by the random number. The maximum of θ is considered to be small because that the Young's modulus of the interface layer is smaller than that of the matrix.View full abstractDownload PDF (334K)
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