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Volume 39 (2011)
- Issue 5 Pages 183-
- Issue 4 Pages 135-
- Issue 3 Pages 93-
- Issue 1_2 Pages 5-
Volume 39, Issue 1_2
A SPECIAL ISSUE FOR NANO/MICRO RHEOLOGY
Displaying 1-11 of 11 articles from this issue
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FOREWORD
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Keiji Sakai2011 Volume 39 Issue 1_2 Pages 5
Published: May 10, 2011
Released on J-STAGE: May 10, 2011
JOURNAL FREE ACCESSDownload PDF (600K)
FEATURE ARTICLE
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Mototsugu Sakai2011 Volume 39 Issue 1_2 Pages 7-15
Published: May 10, 2011
Released on J-STAGE: May 10, 2011
JOURNAL FREE ACCESSThe indentation contact hardness has long been utilized in various engineering fields as well as in scientific studies, since the pioneering works conducted by A. Martens (1898), J.A.Brinell (1900), and E. Meyer (1908). The upsurges of electronics, and computer science and engineering in 1980s lead to the development of instrumented micro/nano-indentation test systems that enable to examine the mechanical properties (elastic modulus, yield strength, hardness, etc.) in micro/nano-scales. These conventional test systems, however, can only measure the indentation load P and penetration depth h hysteresis relation (P -h relation) in a precise manner, and then estimate the mechanical properties through the elastic assumptions to approximate the indentation contact area A at the indentation load P. The present indentation contact mechanics, therefore, cannot be applied to very ductile materials, time-dependent-viscoelastic materials, as well as coating/substrate composite materials, for this elastic assumption/approximation is by no means applied to these nonlinear materials. The author invented a novel instrumented indentation test system, the indentation microscope, that is capable of measuring the in-situe contact area A along with P and h, allowing the rheological characterization of monolithic as well as composite materials with any linear/nonlinear deformation and flow. In the present feature article, the author addresses the viscoelastic indentation contact mechanics, including the principle, theoretical considerations, and the applications.View full abstractDownload PDF (1887K) -
Tadashi Kajiya, Masao Doi2011 Volume 39 Issue 1_2 Pages 17-28
Published: May 10, 2011
Released on J-STAGE: May 10, 2011
JOURNAL FREE ACCESSWe report a series of experimental works about the drying process of polymer solution droplets. Our aims are to analyze the local polymer transport in the drying droplet and to precisely control the profile of polymer film formed after the droplet dries up. For the analysis of the polymer transport, we have established a dynamical observation method for the polymer concentration field by combining the fluorescence microscopy with the lateral profile observation. We observed that a large spatial inhomogeneity of the polymer concentration grows inside the droplet which is caused by the outward capillary flow. For the control of the film profile, we proposed two methods: adding the small amount of surfactant and switching between the solvent evaporation and condensation. These two processes enable us to make a polymer film having a flat profile. Our results propose effective suggestions for controlling the fabrication process of polymer films in inkjet-printing technologies.View full abstractDownload PDF (1475K) -
Masanori Yasuda, Nami Kurauchi, Miki Nakamura, Taichi Hirano, Keiji Sa ...2011 Volume 39 Issue 1_2 Pages 29-35
Published: May 10, 2011
Released on J-STAGE: May 10, 2011
JOURNAL FREE ACCESSViscosity is an important mechanical property of liquid materials referred to in various industrial processes, such as transportation, mixing and coating. Measurement techniques are thus essential for various environments, however, less progress in mythology has been made in recent years, though the conventional method hardly satisfies the variety of user's demands: Requirement arises, for example, to the rapid observation, small quantity of samples, and completely closed system for the viscosity measurement. We introduce in this paper the Electro-Magnetically Spinning (EMS) method, which can settle these problems of the conventional methods. This method has unique features such as, non-contact and rapid measurement, small sample volume, disposable usage, measurement under hermetically sealed condition, which are demonstrated in actual rheology measurement of various materials.View full abstractDownload PDF (1407K)
Original Articles
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Takanobu Ueda, Mika Iga2011 Volume 39 Issue 1_2 Pages 37-42
Published: May 10, 2011
Released on J-STAGE: May 10, 2011
JOURNAL FREE ACCESSThe solvent-based paint has been changed into a water-based paint and higher non-volatile paint because of environmental problems. In addition, the paint film formation process was shortened such as the wet on wet process. In this paper, we measured film formation process using the electric field tweezers in open systems. In multilayer paint film formed by wet on wet process, we measured the dynamic glasstransition temperature of single layer using the differential scanning calorimetry, and we measured crosslinking density of single layer using the micro vickers hardness tester.View full abstractDownload PDF (1189K) -
Tatsuro Matsuoka, Junki Miyashita, Shinobu Koda2011 Volume 39 Issue 1_2 Pages 43-48
Published: May 10, 2011
Released on J-STAGE: May 10, 2011
JOURNAL FREE ACCESSThe theory to obtain the complex strain-optical coefficients was described for the liquids from polarization analysis of a diffracted light by longitudinal ultrasound. The polarization analyses on the isotropic phase of liquid crystal, 4-cyano-4'-pentylbiphenyl (5CB) were carried out at 40, 50 and 60 °C in the frequency range from 5 to 25 MHz.For the +1st and -1st order diffracted lights, values of change in arc tangent of the ratio of electric field and the phase retardation between two polarizations were obtained as functions of square of the Raman-Nath parameter.From intercepts of those values, the complex strain-optical parameters were determined.The frequency dependences of the complex strain-optical parameters at 40, 50 and 60 °C were obtained and compared with those calculated by using the data of using the reorientational relaxation frequency and the flow birefringence per unit strain rate. Although some discrepancies are found at 40 and 50 °C, the results indicate applicability the proposed method to determine the strain-optical coefficients above MHz range.View full abstractDownload PDF (1062K) -
Shigeru Fujino, Seiji Inaba, Toshihisa Kajiwara, Keiji Sakai2011 Volume 39 Issue 1_2 Pages 49-54
Published: May 10, 2011
Released on J-STAGE: May 10, 2011
JOURNAL FREE ACCESSWe propose a novel noncontact method for measuring the viscosity of high-temperature glass melt using a small amount of sample. This method combines the electric-field tweezers system developed for measuring the local and dynamic surface properties of soft condensed materials and the hot-thermocouple technique for in situ observation and measurement of high-temperature liquids. The viscosity of B2O3 melt was measured in the temperature range of 873 to 1473 K. The temperature dependence of the viscosity presented in this work is in reasonable agreement with that reported in the references.View full abstractDownload PDF (838K)
ORIGINAL ARTICLES
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H. Amini Kafiabad, K. Sadeghy2011 Volume 39 Issue 1_2 Pages 55-64
Published: May 10, 2011
Released on J-STAGE: May 10, 2011
JOURNAL FREE ACCESSIn the present work, the collapse of a spherical gas bubble immersed in a Giesekus liquid and subjected to a sudden pressure jump is studied numerically. The main objective of the work is to investigate the role played by the extensional-flow resistance of the surrounding liquid on the bubble dynamics during its collapse. Converged results could be obtained using Gauss-Laguerre quadrature method at very high Deborah and Reynolds numbers over prolonged times. The results show that the extensional-flow behavior of the surrounding liquid, as represented by the mobility factor, has indeed a strong effect on the bubble dynamics. A decrease in the degree of the strain-hardening behavior of the surrounding liquid is predicted to accelerate bubble collapse but only at the early stages of the collapse. At large times, however, it is predicted to have a retarding effect on the bubble collapse. It is also predicted that free oscillations may not exhibit themselves in viscoelastic fluids if the pressure surge is exerted gradually.View full abstractDownload PDF (1531K) -
Naomi Hirayama, Kyoichi Tsurusaki2011 Volume 39 Issue 1_2 Pages 65-73
Published: May 10, 2011
Released on J-STAGE: May 10, 2011
JOURNAL FREE ACCESSWe numerically examine the nonlinear rubber elasticity of topologically constrained polymer networks. We propose a simple and effective model based on Graessley and Pearson's topological model (GP model) for describing the topological effect. The main point is to take account of a nonequilibrium effect in the synthesis process of the polymer network. We introduce a new parameter γ to describe entropic contributions from the entanglement of polymer loops, which may be determined from the structural characteristics of the sample. The model is evaluated in the light of experimental data under uniaxial and biaxial deformations. As a result, our model exhibits uniaxial behaviors which are common to many elastomers in various deformation regimes such as Mooney-Rivlin's relation in small extension, stress divergence in the elongation limit and the declined stress in compression. Furthermore, it is also qualitatively consistent with biaxial experiments, which can be explained by few theoretical models.View full abstractDownload PDF (1189K) -
M.R. Khorsand, F. Rashidi, F. Goharpey, M. Mirzazadeh, E. Amani2011 Volume 39 Issue 1_2 Pages 75-85
Published: May 10, 2011
Released on J-STAGE: May 10, 2011
JOURNAL FREE ACCESSIn this study prediction of the steady-state flow of branched polymer melts in pipe geometry with finite volume method is presented. The fluid is modelled using a modification of the Pom-Pom model known as the single eXtended Pom-Pom (XPP) where viscoelastic fluid, is typically a commercial low-density polyethylene. In finite volume method, the operator-integration is used to discretize the governing equations in space or control volume. An iterative solution algorithm that decouples the computation of momentum from that of stress is used to solve the discrete equations. Numerical results are presented; include the profiles of all relevant stresses, the axial velocity, stretch and the viscosity across the gap, demonstrating the performance of the model predictions. The influence of the model parameters on the solution and flow behaviour is described and, in particular, the dependence of velocity and stresses distribution as a function of Weissenberg number is analyzed. Finally, for rectitude and accuracy, the verification of this model is performed with the Gieskus model that shows good conformity between the results.View full abstractDownload PDF (1587K)
Note
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Katsuhiro Inomata, Marika Ogiso, Ayu Kobayashi, Hiroyasu Hasegawa, Ken ...2011 Volume 39 Issue 1_2 Pages 87-92
Published: May 10, 2011
Released on J-STAGE: May 10, 2011
JOURNAL FREE ACCESSSmall amount of impurities or contaminations in recycled plastic have a possibility to influence on mechanical properties of product. In this study, miscibility and mechanical properties of melt-blended high-impact polystyrene (HIPS) and poly(α-olefin) (PO)-based grease have been investigated. We have focused attention on the molecular weight (Mw) of PO, and the range of Mw for PO in the used greases was 690-8,500. Changes of glass transition temperature were observed for polystyrene and polybutadiene phases in the HIPS/grease blends, that indicated small amount of PO was solubilized into HIPS. When Mw of PO was higher than 5,000, insoluble excess PO acted as lubricant, and sample preparation was difficult since slipping between the polymer and chamber wall or screw occurred during melt blending. By this limitation in solubility of HIPS/grease, depression of mechanical properties such as flexural modulus and strength for the obtained blends was not remarkable. On the other hand, blends with high grease content could be obtained for PO with low Mw because of its good solubility with HIPS, as the result, their flexural properties were highly deteriorated than the original HIPS. Therefore, the grease containing high molecular weight PO has a smaller influence on the mechanical properties of HIPS/grease because of the limitation in solubility. Results of chemical stress crack tests for HIPS/grease were also explained by the miscibility of PO with HIPS.View full abstractDownload PDF (798K)
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