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Volume 37 (2009)
- Issue 5 Pages 211-
- Issue 4 Pages 173-
- Issue 3 Pages 121-
- Issue 2 Pages 57-
- Issue 1 Pages 1-
Volume 37, Issue 1
Displaying 1-7 of 7 articles from this issue
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Feature Article
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Walter Noll, Brian Seguin2009 Volume 37 Issue 1 Pages 1-10
Published: February 15, 2009
Released on J-STAGE: April 16, 2009
JOURNAL FREE ACCESSIn 1966, Coleman, Markovitz and Noll published a book entitled Viscometric Flows of Non-Newtonian Fluids. The analysis presented there is based on the concept of an incompressible simple fluid (simple liquid), which Walter Noll had introduced in 1958. About 5 years ago he introduced the concept of a simple semi-liquid. It turns out that the analysis given in the book mentioned above can be extended to simple semi-liquids. The behavior of simple liquids in viscometric flows is characterized by three functions: the shear-stress function and two normal stress functions. This remains true for simple semi-liquids, but now the limits of these functions as the rate of shear goes to zero need not be zero but may approach critical non-zero values. This fact allows the existence of plugs. This paper gives explicit procedures for determining the size of plugs for the entire variety of viscometric flows analyzed in the book mentioned above.View full abstractDownload PDF (1674K)
Original Articles
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Akio Nasu, Yasufumi Otsubo2009 Volume 37 Issue 1 Pages 11-15
Published: February 15, 2009
Released on J-STAGE: April 16, 2009
JOURNAL FREE ACCESSFine particles of titanium dioxide (TiO2) are effective UV-protecting inorganic materials in cosmetic products. The particles have the tendency to make flocs in liquids and the ability of UV light scattering of the suspensions strongly depends on the size of flocs. The degree of flocculation should be related to the rheological properties, and UV-protecting ability of the suspensions was investigated as a function of the size of flocs formed in a dispersion procedure during sample preparation. Essential requirements for UV-protecting cosmetics are strong cut-off ability for the UV light and high transparence for the visible light. Excellent balance of these optical properties was achieved in the suspensions of TiO2 particles with floc diameters ranging from 100 to 120 nm. When the floc diameter was decreased less than 100 nm in the dispersion procedure, the suspensions turned to shear-thinning fluids from Newtonian ones. Such the change in rheological behavior can be used to obtain TiO2 suspensions possessing the designed UV-protecting ability and flow behavior.View full abstractDownload PDF (254K) -
Katsufumi Tanaka, Naoyuki Sezaki, Hyota Nakahori, Ryuichi Akiyama2009 Volume 37 Issue 1 Pages 17-23
Published: February 15, 2009
Released on J-STAGE: April 16, 2009
JOURNAL FREE ACCESSThe steady shear flow behavior of the electro-rheological (ER) nano-suspensions with different volume fractions of particles (φ) was investigated under no external electric fields. The apparent yield stresses were found for the samples with φ = 2.4 and 8.8 vol%, and they were discussed with the results of the apparent viscosity as well as the absolute values of the complex viscosity. Macroscopically developed microstructures of secondary particles were observed for the two samples in the quiescent state. On the other hand, no plateau region was measured for the sample with φ = 1.2 vol%, and secondary particles on the order of several micrometers were observed to be separately distributed. The apparent yield stresses were also discussed in relation to the microstructures for the nano-suspensions. It was proposed that randomly distributed secondary particles or a macroscopically developed microstructure of secondary particles in the nano-suspension should also be taken into account for the initial state of the ER effect, other than randomly distributed primary particles generally assumed so far.View full abstractDownload PDF (370K) -
Aggregation Behavior of the Styrene Units in Oil Gel of Styrene-Butadiene-Styrene Triblock CopolymerShigeru Machida, Naomi Takahashi, Yasuhiro Matsuda, Shigeru Tasaka2009 Volume 37 Issue 1 Pages 25-29
Published: February 15, 2009
Released on J-STAGE: April 16, 2009
JOURNAL FREE ACCESSDifferential scanning calorimetry (DSC) and viscoelastic measurements were carried out for oil gels formed by styrene-butadiene-styrene triblock copolymer (SBS) and naphten oil or 1-octadecene to investigate the mechanism of their gelation. There were three endothermic peaks in the DSC curves assigned as the glass transition of the butadiene units, that of the styrene units, and the dissolution enthalpy of the styrene units and solvent oils. The G' of the SBS gels showed a specific depression near the glass transition temperature of the styrene units, determined by DSC. The modulus curve had also a shoulder at the gel melting temperature determined by the tilting test tube method. The structure and gelation mechanism of SBS gel were discussed on the results of the measurements.View full abstractDownload PDF (364K) -
Mohammad Mirzadeh, Kayvan Sadeghy2009 Volume 37 Issue 1 Pages 31-38
Published: February 15, 2009
Released on J-STAGE: April 16, 2009
JOURNAL FREE ACCESSAn exact solution has been found in plane stagnation flow for a viscoelastic fluid obeying the Giesekus model. The flow was found to render itself to a local similarity solution in the vicinity of the stagnation point. The solution so obtained could easily enable one to investigate the effects of parameters such as Reynolds number, Weissenberg number and the mobility factor on the velocity and stress fields. Unlike Newtonian and Maxwellian fluids, the thickness of the boundary layer was found to be a decreasing function of the distance from the stagnation point. It will be shown that this effect may have roots in the extensional behavior of the fluid.View full abstractDownload PDF (843K) -
Makoto Okawara, Tomiichi Hasegawa, Nobuhiro Yamada, Takatsune Narumi2009 Volume 37 Issue 1 Pages 39-46
Published: February 15, 2009
Released on J-STAGE: April 16, 2009
JOURNAL FREE ACCESSIn a previous paper we clarified the behavior of pressure losses ΔP for aqueous solutions of cetyltrimethylammonium bromide (CTAB) and sodium salicylate (NaSal) in an elongation dominant flow through slots: the flow curves relating ΔP to the apparent elongational rate consisted of three characteristic regions. In particular, ΔP increased largely in a specific region II, and this characteristic was suggested to be closely connected to the flow induced structure (FIS). However, it could not be asserted that FIS solely causes the large increase in ΔP, because vortices were also found in the flow upstream of the slot in region II and such vortices are known to induce large pressure drops frequently. In the present experiment, we used a nozzle providing almost the same constant elongational rate as the slot in order to eliminate the influence of vortices on ΔP, estimated elongational rates of the upstream flow, compared ΔP for both the slot and the nozzle, and concluded that vortices existing in the region upstream of the slot do not give a significant effect on ΔP. Next, the image of small angle light scattering (SALS) was examined to clarify the developing process of FIS: A butterfly-type and streak-type combined pattern in SALS occurs in region II, indicating the generation of FIS; the streak-type pattern degenerate at higher elongational rates in region III, meaning a partial collapse of FIS generated in region II; change in FIS depends not only on strain rate but also on strain in elongational flow. Moreover it was found that FIS shows a step-like development in the upstream flow of constant elongational rate.View full abstractDownload PDF (874K)
Note
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Hiromasa Adachi2009 Volume 37 Issue 1 Pages 47-50
Published: February 15, 2009
Released on J-STAGE: April 16, 2009
JOURNAL FREE ACCESSFor evaluation of shearing loss tangent of thermosetting polyurethane elastomers pasted bonding tape made by acryl foam were investigated by dynamic viscoelastic measurements. Loss tangent of two layer type sample is among the loss tangent of thermosetting polyurethane elastomers and the loss tangent of bonding tape made by acryl foam. The larger the thickness of bonding tape or the larger the storage modulus of the thermosetting polyurethane elastomers, the loss tangent of compound model type sample in normal temperature become to be larger. The larger the difference of the storage shearing modulus of thermosetting polyurethane elastomers and adhesive on surface of bonding tape, the loss tangent of compound model type sample may be larger by the hystereisis of the shearing deformation.View full abstractDownload PDF (278K)
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