All issues
Volume 29 (2001)
- Issue 4 Pages 165-
- Issue 3 Pages 105-
- Issue 2 Pages 71-
- Issue 1 Pages 9-
Volume 29, Issue 3
Displaying 1-7 of 7 articles from this issue
- |<
- <
- 1
- >
- >|
Original Articles
-
Katsufumi Tanaka, Kensuke Ichizawa, Ryuichi Akiyama, Atsushi KubonoArticle type: Article
2001 Volume 29 Issue 3 Pages 105-109
Published: 2001
Released on J-STAGE: June 14, 2003
JOURNAL FREE ACCESSSimultaneous measurement of rheological behavior and conduction current was performed for an electro-rheological (ER) suspension with a dilute concentration of cation exchange resin particles of 5 wt%. The stress under the electric field for the ER suspension showed a remarkable dip behavior at higher shear rates: The stress decreased with an increase in the shear rate, and it gradually increased again and approached the stress under no electric field. The apparent conductivity, which was sensitively probed by the conduction current passing through the ER suspension, showed a dip behavior. Further, the apparent conductivity showed a local maximum, which was not found for the ER suspensions with particle concentrations of 10 and 30 wt%.View full abstractDownload PDF (168K) -
Wanhu Zhang, Satoshi Komoto, Hideki Yamane, Masaoki Takahashi, James L ...Article type: Article
2001 Volume 29 Issue 3 Pages 111-120
Published: 2001
Released on J-STAGE: June 14, 2003
JOURNAL FREE ACCESSChange in fiber orientation in glass fiber filled polypropylene (PP/GF) melts was observed with scanning electron microscopy after quenching the samples in biaxial extensional flow. The upturn of biaxial extensional viscosity from the low strain rate asymptote decreases by the addition of glass fibers, due to suppression of polymer chain extension. When the binder of glass fibers is immiscible with the matrix, fiber dispersion becomes worse and there appears a very small upturn in the biaxial viscosity. It has been found that there is an appropriate range of strain rate where the glass fibers orient well to the flow direction. This range corresponds to the range where the strain rate is much greater than the rate of fiber orientation and it is smaller than or comparable with the relaxation rate of the matrix chain. In this range, the degree of fiber orientation decreases with increasing the strain rate. It is suggested that the fibers take time to orient and cannot follow the fast flow in this range where the matrix does not have enough power to orient the fibers.View full abstractDownload PDF (463K) -
Kuniyoshi ItoyamaArticle type: Article
2001 Volume 29 Issue 3 Pages 121-129
Published: 2001
Released on J-STAGE: June 14, 2003
JOURNAL FREE ACCESSIsothermal volume contraction due to physical aging was measured for linear poly(ethylene terephthalate)(PET) glasses and for branched PET glasses of ethylene terephthalate-trimellitic(TMA) copolyesters. Materials were subjected to various thermal annealing treatments at temperatures above their glass transition temperatures (Tg), and then aged at temperatures ranging from Tg-10 °C to Tg with aging time ranging from 10 min to 7 days. Over the range of temperatures studied, normalized volume data for the annealed glasses could be superimposed using aging time-temperature superposition. The shape of reduced curves not to be described by a stretched exponential function was drastically influenced by thermal annealing conditions. It was found that a change of amorphous structures in the linear and lightly branched PET glasses due to annealing resulted in significant acceleration of the rate of volume relaxation. Furthermore, the correlation between the local rearrangement of amorphous network chains and the volume relaxation process of polymer glasses was discussed.View full abstractDownload PDF (592K) -
Hideo Asama, Tomiichi Hasegawa, Takatune NarumiArticle type: Article
2001 Volume 29 Issue 3 Pages 131-137
Published: 2001
Released on J-STAGE: June 14, 2003
JOURNAL FREE ACCESSMeasurement of the elastic stress of viscoelastic fluids at high strain rates is important in industry, but hard for conventional rheometers. We have developed a new type of apparatus based on the jet reaction method for measuring the elastic stress. The new apparatus is smaller in size and simpler in treatment than the one that has been used so far. Load test of the apparatus and comparison with the other apparatuses reveal that the present apparatus has a confidence in measurement of elastic stress at high strain rates. In this paper, we present several kinds of data measured in shear flow and elongational flow by the present apparatus.View full abstractDownload PDF (204K) -
Toru MASUKO, Masuo KOMOTO, Hideaki ISHIJIMA, Yoshifumi YAMAGATAArticle type: Article
2001 Volume 29 Issue 3 Pages 139-143
Published: 2001
Released on J-STAGE: June 14, 2003
JOURNAL FREE ACCESSThe rheological characteristics of synthetic hectorite/water suspensions have been measured by a cone-plate rheometer as a function of additive NaCl concentration (CNaCl). The hectorite particles, dialyzed preliminarily to remove electrolytic impurities involved, were utilized for preparing a 2.0 wt% aqueous suspension. The apparent viscosities of the suspensions decreased monotonically with increasing CNaCl; these changes in the viscosities came from the primary electroviscous effect. In dynamic viscoelastic measurements of the suspensions, we found that the critical strain also decreased with increasing CNaCl. By the use of a Cryo-SEM, we observed that different types of the particle-coagulated structures in the various suspensions with respective NaCl concentrations. These findings can be explained by the different interaction modes originated from the electrostatic charge near the surface of hectorite particles, as in the following situations : (1) in the low CNaCl region, the electrostatic repulsion among the particles leads effectively to form an expanded network structure in the system; (2) in the high CNaCl region, the van der Waals attraction force among the particles governs the interaction mode in the system, thus resulting to form a dense-packed coagulation structures.View full abstractDownload PDF (1493K) -
Akihisa TSUKAMOTO, Tatsuya MATSUMURA, Yukuo NANZAIArticle type: Article
2001 Volume 29 Issue 3 Pages 145-151
Published: 2001
Released on J-STAGE: June 14, 2003
JOURNAL FREE ACCESSIn order to study the effect of aging on the mechanical strength of thermoformed thermoplastics, we carried out uniaxial tensile test of thermoformed poly(methyl-methacrylate) (PMMA). Thermoformed and aged specimens were generally much more ductile in its longitudinal direction in comparison with the unstretched ones. The ductility of longitudinal specimens was reduced by aging. Sheets aged at a temperature of 50°C for an aging time of 50h had quite high ductility in the longitudinal direction. Yet, ductility of specimens cut in the transverse direction was little affected by aging. These data bring us to predict toughness for aging in the thermoformed PMMA sheet.View full abstractDownload PDF (477K)
Note
-
Hiromasa ADACHI, Teruo HASEGAWAArticle type: Note
2001 Volume 29 Issue 3 Pages 153-156
Published: 2001
Released on J-STAGE: June 14, 2003
JOURNAL FREE ACCESSEffects of cell destruction on compression moduli of five expanded polystyrene foams were studied by the static compression test and the dynamic viscoelastic measurements in compression mode. In the static compression test, stress-strain curves of virgin foams gave a bend in the small strain region but exhibited no yield behavior as observed for hard polyurethane foams, whereas the stress monotonically increased with strain for foams whose cells were artificially destroyed. It is considered that cells are rapidly destroyed in the bend region without breakage of the entire foam in contrast to slow cell destruction of hard polyurethane foams. In comparison of the static compression modulus obtained from the initial slope of the stress-strain curve at the strain of 0.04 with the dynamic compression modulus, the former has been found to correlate with the latter positively in two types of foams before and after destruction of cell, and the latter is larger than the former. The appearance of the viscoelastic behavior of natural open-celled foams is considered to be difficult because of the buckling more easily than hard polyurethane foam.View full abstractDownload PDF (80K)
- |<
- <
- 1
- >
- >|