巻号一覧
16 巻 (1988)
- 4 号 p. 129-
- 3 号 p. 89-
- 2 号 p. 53-
- 1 号 p. 4-
16 巻, 2 号
選択された号の論文の4件中1～4を表示しています
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高橋 雅興1988 年 16 巻 2 号 p. 53-65
発行日: 1988/06/20
公開日: 2012/11/20
ジャーナル フリーA critical review is presented on the recent constitutive models for polymer liquids. Among others, the Leonov, the Giesekus and the Larson models are discussed on their fundamental ideas, main assumptions and applicability to some nonlinear viscoelastic phenomena in concentrated polymer systems. These models have fairly wide applicability compared with other models. However, each model has two or three defects or weak points.
Three defects of the Leonov model are: (1) a few phenomenological assumptions made without a firm basis,(2) weak molecular theoretical reasoning of the strain-hardening parameter β, and (3) difficulty in determining the value of β for mixed flows which include shear and extension. Two defects found for the Giesekus model are:(1) lack of the idea of chain contraction and (2) difficulty in extending the model to the case of multiple relaxation times. Three defects of the Larson model are:(1) mathematical approximations made to obtain the constitutive equation,(2) lack of theoretical or experimental justification for the idea of partially extending convection in branched polymers, and (3) inapplicability of the assumed separable form G(t,γ)=G(t)h(γ) to the short-time behavior in stress relaxation.
It is emphasized that future models should be developed based on the molecular theoretical consideration to express correctly the following interrelations; different mode of deformation (shear, uniaxial or biaxial extension)→different extent of orientation and extension of polymer chains↔difference in the stress level.抄録全体を表示PDF形式でダウンロード (2383K) -
-破壊挙動-中丸 八郎, 柚木 貴之, 長瀬 洋一1988 年 16 巻 2 号 p. 66-71
発行日: 1988/06/20
公開日: 2012/11/20
ジャーナル フリーAs an extension of previous studies on the dilute solid-liquid suspensions, this paper describes the rheological behavior of suspension at very high concentrations, the sludge. An unconfined compression (uniaxial compression) was applied for cylindrical block of Na Bentonite-water sludge. Various hystereses of stress or strain were applied until the block was ruptured. Before the rupture, the deformation was viscoelastic and the non-recoverable part of strain depended on the hysteresis. The rupture stress depended only on the concentration, and was independent of the hysteresis of stress or strain. The rupture strain varied with the hysteresis and the concentration and it was always less than 0.1. The modulus plotted against the rupture stress for sludge laid on the extension of the line for the modulus plotted against the yield stress for dilute suspensions. It was concluded that the rupture of sludge corresponds to the yielding of suspension, though the former is viscoelastic before rupture and the latter is elastic before yielding. In the creep test, the strain response, immediately after the loading, was elastic, and then becomes viscoelastic. These responses could be represented by a four-element model if the obvious non-linearity at the initial stage of creep is ignored. The initial properties were recovered again by keeping the material at rest; thus the sludge has a thixotropic nature.抄録全体を表示PDF形式でダウンロード (837K) -
井上 正志, 根本 紀夫, 児島 誉治, 綱島 良祐, 倉田 道夫1988 年 16 巻 2 号 p. 72-80
発行日: 1988/06/20
公開日: 2012/11/20
ジャーナル フリーAn instrument was constructed for studies of self diffusion of polymer in solution. The self diffusion coefficient, Ds, could be measured by using either of the fluorescence recovery after pattern photo-bleaching (FRAPP) or the forced Rayleigh scattering (FRS) techniques with slightly different experimental setups. These techniques are similar in parinciple. In both techniques, Ds is estimated from the relaxation process of intensity of light (fluorescence or diffracted light) due to redistribution after formation of grating-like pattern by photo-bleaching of polymers labeled with photo-bleachable dyes. Capability of the instrument was demonstrated from Ds measurements on solutions of two narrow distribution polystyrene samples with Ms=43,900 and 355,000 in dibutylphthalate in the range of polymer concentration from 1 to 50 wt%. The time variation of intensity of light from the two techniques, FRAPP and FRS, could be fitted with single exponential curves suitable for respective theoretical prediction. Values of Ds estimated with the two methods agreed with each other over the range of Ds values from 10-8 to 10-12cm2/s.抄録全体を表示PDF形式でダウンロード (1250K) -
尾崎 邦宏, 高取 永一1988 年 16 巻 2 号 p. 81-85
発行日: 1988/06/20
公開日: 2012/11/20
ジャーナル フリーThe birefringence in steady shear flow was calculated for a triblock copolymer of an ABA type. The calculations were carried out for the Rouse model and the tube model. It was shown that the stress-optical law would not hold valid for a triblock copolymer. An apparent stress-optical coefficient Cσ=Δn sin 2χ/2σ was evaluated for the case where only the B segments were optically anisotropic and contributed to the birefringence. Here Δn is the birefringence, χ is the extinction angle, and σ is the shear stress. When the content of B component, ξ, was small, Cσ at the limit of low rate of shear was 1.5 times as large as the average stress-optical coefficient evaluated from ξ. The factor decreased and approached unity with increasing ξ. The quantity Cσ evaluated from the tube model decreased with increasing rate of shear. These features of birefringence, if confirmed experimentally, would prove that the contribution to stress of a polymer segment depends on its position along the chain and is the larger as it is closer to the center of the chain.抄録全体を表示PDF形式でダウンロード (653K)
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