日本レオロジー学会誌
Online ISSN : 2186-4586
Print ISSN : 0387-1533
ISSN-L : 0387-1533
23 巻, 2 号
選択された号の論文の7件中1~7を表示しています
  • 根本 紀夫, 小池 晃広, 桑原 三恵, 尾崎 邦宏
    1995 年 23 巻 2 号 p. 65-74
    発行日: 1995/06/15
    公開日: 2012/11/20
    ジャーナル フリー
    This article summarizes recent experimental studies on dynamics of CTAB/NaSal micellar network performed with dynamic viscoelasticity, forced Rayleigh scattering, and dynamic light scattering methods. The unique dynamical behavior of this threadlike micelle system is discussed in terms of mechanical relaxation time τM, steady viscosity η, self diffusion coefficient D, cooperative diffusion coefficient Dc, and first cumulant Γe or its reciprocal Γe-1s obtaind over wide ranges of surfactant concentration CD, ratio of salt concentration Cs to CD, and temperature T.
  • Yasufumi OTSUBO
    1995 年 23 巻 2 号 p. 75-80
    発行日: 1995/06/15
    公開日: 2012/11/20
    ジャーナル フリー
    The steady shear viscosity, dynamic viscoelasticity, and creep were measured for suspensions flocculated by polymer bridging and depletion. Irrespective of flocculation mechanism, the suspensions are shear-thinning in a wide range of shear rates. However, the elastic properties are quite different. The suspension flocculated by bridging shows a plateau in the frequency-dependent curve of dynamic viscoelastic function. The floc structures with a very long relaxation time are developed over the system. On the other hand, the suspension flocculated by depletion behaves as a viscous liquid without elasticity. The flocs hardly accumulate the elastic energy. The polymer bridges transmit central and transverse forces. However, since the osmotic pressure is responsible for attractive forces in depletion flocculation, the bonds show little resistance with respect to transverse bending forces. Because of shear motion of particles, the strain energy is rapidly dissipated in suspension flocculated by depletion. The elastic properties of flocculated suspensions are determined by the vector nature of bond.
  • 四方 俊幸, 丹羽 宏和, 小高 忠男
    1995 年 23 巻 2 号 p. 81-87
    発行日: 1995/06/15
    公開日: 2012/11/20
    ジャーナル フリー
    Linear viscoelastic behavior was examined for suspensions of an ultra-fine silica particle, S7.5, with a radius of 7.5nm dispersed in highly viscous medium consisting of ethylene glycole and glycerin, and was compared with that of previously examined suspensions with radii larger than S7.5. A S7.5, system exhibited remarkable viscoelasticity as well as systems with larger radii, and the zero-shear viscosity, η0, the high frequency limiting viscosity, η′, and the high frequency limiting modulus, G, could be estimated. However, the dependence of η0 and η′ on particle concentration for the S7.5 system was completely different from universal one holding in the larger particle systems independently of particle radii. The size of the S7.5 is so small, that the contribution of a special interface layer formed by interacting medium molecules with the surface of the S7.5 to gross rheology becomes important in contradiction to the larger particle systems. The relationship between η0′ and patticle volume fraction, φ, holding in the larger particle systems which are hard-core suspensions was extended to the S7.5 system. Then, the effective volume fraction, φeff, and the effective medium viscosity, ηm+, for the S7.5 system was estimated by rescaling the system to an equivalent hard core suspension system. The average relaxation time for the system could be successfully regulated by the φeff not by φ, however, the G could be simply governed by the original φ just like found in the hard core suspensions.
  • Yoshinori KASHITA, Takashi HATANO, Takayoshi MATSUMOTO
    1995 年 23 巻 2 号 p. 89-94
    発行日: 1995/06/15
    公開日: 2012/11/20
    ジャーナル フリー
    Random copolymers of acrylonitrile (AN), vinylchloride (VC) and vinylidenechloride (VD) are dissolved in acetone for a certain range of copolymer composition, though homopolymers of these components are not dissolved. In this study, mechanism of the above phenomenon, which has not been clarified, was investigated from a structural and rheological point of view.
    Steady flow and dynamic viscoelastic properties of concentrated acetone solutions of random acrylic resins (AN-VC, AN-VD, AN-VC-VD) were measured by means of a cone-plate type rheometer. Rheological properties and microscopic structure were studied in relation to mole fraction of each component in the copolymers.
    A binary AN-VD copolymer of AV/VD=65/35 (in mole fraction) shows a critical gel behavior (i. e. G′~G″~ωn) at 30wt%. On the other hand, the system of AN/VD=55/45 shows still Newtonian flow and flow behavior (i. e. G′~ω2, G″~ω1) at 40 wt%. These phenomena can be elucidated by decreasing of the solubility of the copolymers with increasing AN content.
    An AN-VC system of the AN/VC=53/47 forms a gel at 10~15wt%. The systems with high VC content form a thermo-reversible gel in acetone.
  • 山本 智, 松岡 孝明
    1995 年 23 巻 2 号 p. 95-101
    発行日: 1995/06/15
    公開日: 2012/11/20
    ジャーナル フリー
    A numerical simulation method has been developed to predict the rheological behavior of fiber suspensions in shear flow by using the particle simulation method (PSM), in which a fiber is modeled by arrays of spheres. The hydrodynamic interaction among fibers is considered by decomposing into intra- and inter- fiber ones. In the former, the many-body problem is solved by calculating the mobility matrix for each fiber to obtain the hydrodynamic force and torque exerted on each sphere. In the latter, only the near-field lubrication force is considered between spheres belonging to different fibers. The methodology was applied to predict the microstructure and the rheological properties of suspensions of rigid fibers with aspect rations 5 and 10 at several cancentrations. The overshoot of suspension viscosity due to the transient change from random to planar orientation in the microstructure was observed in semi-dilute to concentrated regimes.
  • 八尾 滋, 亀井 衛一
    1995 年 23 巻 2 号 p. 103-108
    発行日: 1995/06/15
    公開日: 2012/11/20
    ジャーナル フリー
    The internal morphology and the viscoelastic properties of polymer blends and polymer alloys are strongly influenced by the interfacial interaction between molten polymers.
    The interfacial interaction energy between two molten incompatible polymers was estimated using molecular mechanics and molecular dynamics. The calculated energy values correlate very well with the measured interfacial tensions. This calculation method was applied to the polypropylene (PP) and the poly (ethylene-co-propylene) (EP) systems to investigate the effects of the sequence difference of the copolymer. The interfacial interaction energy in the system of the PP and the EP with poly (ethylene-alt-propylene) ([E1-P1]n), is stronger than in the system of [E10-P10]n. This implies that the former is more soluble with PP than the latter. The temperature dependence of the interfacial interaction energy was also predicted by this calculation method.
  • Cone-plate Type Fourier Transform Rheometerの開発
    上田 隆宣
    1995 年 23 巻 2 号 p. 109-113
    発行日: 1995/06/15
    公開日: 2012/11/20
    ジャーナル フリー
    This paper proposes a new method for measuring frequency dependence of G′ and G″, using a coaxial cone-plate type rheometer oscillated by multifrequency wave, named Fourier Transform Rheometer (FT-RM). The experimental results manifest that this FT-RM is much more superior than the conventional dynamic method for obtainning the freaquency dependence curves of G′ and Gn for disperse systems in transition state. The FT-RM is more acculate for the measurements in curing process of automobile primer paint than a pulse method using a Raised Cosine Pulse. A gel point of the coated layer is specified by the frequency dependence curves of G′ and G″ at various temperatures. Effect of shearing on the viscoelastic properties is also examined in silica dispersions using an electromagnetic induction torque transducer. For the disperse systems including chemically modified hydrophobic silica with a good affinity for vehicle, G′ increases with shearing process. On the other hand for the suspensions of untreated silica with poor affinity for vehicle, G′ decreases with shearing process.
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