巻号一覧
32 巻, 6 号
選択された号の論文の8件中1～8を表示しています
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遠藤 守信, 小山 恒夫1976 年 32 巻 6 号 p. P177-P185
発行日: 1976/06/10
公開日: 2008/11/28
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加藤 邦雄1976 年 32 巻 6 号 p. P186-P191
発行日: 1976/06/10
公開日: 2008/11/28
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山口 拓治, 柳川 昭明, 木村 博1976 年 32 巻 6 号 p. T227-T237
発行日: 1976/06/10
公開日: 2008/11/28
ジャーナル フリーIn the present paper, an equation of nonlinear superposition principle proposed by Schapery is simplified so that the dependences of equilibrium term of relaxation modulus on strain are identical with that of transient term, and this equation is named general model (model G). From this equation, the several nonlinear constitutive equations can be derived as follows.
(1) Time-strain factorized model
(a) Perfect factorized model (model I)……nonlinearity depends on present strain.
(b) Imperfect factorized model (model II)……nonlinearity depends on strain history.
(c) Mixed factorized model (model M)……to combine model I with model II.
(2) Time-strain reduced model (model III)……the strain to change time scale.
(3) General model (model G)……to combine model M with model III.
It is difficult to assign nonlinear viscoelastic property of a given material to one of the above five models by single step stress relaxation tests. In particular, it is emphasized for power law's materials.
By two step stress relaxation tests, nonlinear characteristics of materials are classified into five models as follows:
The time tN, when effects of the first strain ε1, decay and hence two step relaxation stress σ2(t′) under ε2(=ε1+Δε) meets single step relaxation stress σ1(t′) at ε2, depends on only t1 (input time of Δε) for the time-strain factorized models. For other models, tN depends on ε1, ε2 and t1. In each case of model I, II and M, |_??_σ1/_??_ε2| is linear to ε1, independent of ε1, and nonlinear to ε1, respectively. The another useful properties are that Δσ/ε1 (Δσ=σ2-σ1) decrease with ε2, ε1, and both ε1 and ε2, respectively, for model I, 11 and M. The stress increment δσ at t1 has only linear relation to Δε for the model III, while δσ is nonlinear to all ε1, ε2 and t1 for the model G.
The theory is tested for some polyethylenes at room temperature. The samples have nearly power law's properties in single step stress relaxation behavior. The measured values of tN have properties of the model III or G. Only when Δε>0 and ε1_??_2%, the experimental curves of o2(t′) agree well with the calculated curves from model III. When ε1=3% and Δε>0, the calculated values are less than the experimental values. When Δε<0, the calculated values are greater than experimental values. In this case, if nonlinearized function aε (ε) is provided with property of hysteresis, the theory of model III may be improved to approach the experimental results.抄録全体を表示PDF形式でダウンロード (663K) -
山口 拓治, 笠嶋 文夫, 柳川 昭明, 木村 博1976 年 32 巻 6 号 p. T237-T247
発行日: 1976/06/10
公開日: 2008/11/28
ジャーナル フリーSuperposition principle of the Schapery type, discussed in a previous paper, is examined by the experiments of loading, unloading and stress relaxation after ceasing of loading, under constant rate of elongation, for low and high density polyethylene films.
In loading process, the calculated values from time-strain reduced model (model III) agree well with the experimental values to 5 and 3% in strain for the low and high density samples, respectively. But, the perfect time-strain factorized model (model I) can be applied only in the limited range of small strain.
In stress relaxation process for the low density sample, the rates of relaxation in the observed curves are a little higher than that in the predicted curves from model III. While for the high density sample, the theory of model III has good agreements with experiments.
In unloading process, the calculated values from both models are greater than the experimental values. In other words, the observed strain recovery in unloading delays in comparison with the predicted recovery. These tendencies are remarkable for the high density sample. The discrepancy between theory and practice is explained as follows.
It is considered that plastic strain develops in loading process, not recovers by unloading and would affect the reduced factor aε(ε). In the theory of model III, it is assumed that aε(ε) in unloading is equal to that in loading at the same strain. However, when plastic strain yields, the value of aε(ε) would decrease and the stress decay would be accelerated. Since, the unloading stress would be less than the expected value. These considerations are grounded on the view of Ferry's free volume theory.
If aε(ε+εb) is substituted for aε(ε) under unloading process in model III, the calculated values well agree with the experimental results, where εb is shift strain and should be determined by the method of trial and error, but depends on the value of plastic strain.抄録全体を表示PDF形式でダウンロード (610K) -
清水 二郎, 島崎 恒蔵1976 年 32 巻 6 号 p. T248-T253
発行日: 1976/06/10
公開日: 2008/11/28
ジャーナル フリーThe rapid cooling effect of polypropylene melt spinning reported in the previous paper, is discussed on the base of the experiments carried to investigate the influence of the force (stress) acting on a filament. The polypropylene with its molecular weight degraded by irradiation (γ-rays of Co 60) was employed to confirm the influence for the rapid cooling effect.
The force acting on a filament was given by the frictional force which was changed by the contact angle between the guide and a filament (Fig. 1). From the experimental results, it was made clear that the rapid cooling effect was greatly influenced by the force acting on a filament, immediately after it was cooled rapidly by a water bath.
It was presumed that the stress contributes the increase of molecular orientation before crystallization and the high orientation can therefore be obtained during crystallization.
On the other hand, the rapid cooling effect depends upon the molecular weight of polypropylene. The dependence of molecular weight on the rapid cooling effect, was considered in this way. In the process of rapid cooling, the polymer viscosity considered to contribute to the increase of molecular orientation before crystallization, depends upon the molecular weight, which also contributes to the increase of crystallizability (molecular movability) at low temperatures as reported in the previous paper.抄録全体を表示PDF形式でダウンロード (471K) -
中野 詔彦, 長谷川 澄子1976 年 32 巻 6 号 p. T254-T264
発行日: 1976/06/10
公開日: 2008/11/28
ジャーナル フリーEffects of temperature and strain speed on the fracture formation of polystyrene have been studied in terms of the fracture surface morphology and the mechanical property. Elongation of polystyrene indicates the minimum point at 40_??_70°C. That point is in accord with the temperature at which fracture surface indicates all mirror region. Below the minimum temperature, rising temperature is almost the same as lowering the molecular weights in terms of the mechanical property and mechanism of occurrence of the craze and fracture surface morphology.
Brittle region indicates the fracture with the unstable crack propagation and mirror region indicates the fracture with the stable crack propagation or craze propagation.
Ductile region indicates the fracture with the incorporation and growth of defects. Degree of fluidity is able to put a quantitative definition with the change of area of each region on fracture surface.
It is concluded that the reason for decrease of elongation of polystyrene is formation of the craze, the elongation decreases with increase of mirror region area on the fracture surface, and all fracture surfaces become mirror region at the temperature of minimum point of elongation.抄録全体を表示PDF形式でダウンロード (5786K) -
三軒 斉, 山本 吉威, 今村 力造1976 年 32 巻 6 号 p. T264-T271
発行日: 1976/06/10
公開日: 2008/11/28
ジャーナル フリーPolyether-copolyester block copolymer (T/i_??_Ph-E1540), in which the aromatic homopolyester (T) usually serves as the hard segment (the crystallizable parts of chains) were replaced by the aromatic copolyester (T/i_??_Ph), were synthesized.
In this case, since the replacement of the hard segment depressed the rates of the growth of their crystallites and caused their crystallinity to decrease, the lowering of the fiber-strength was presupposed. It was suggested that this lowering would be compensated by increasing of the quantity of the hard segment.
The purpose of this work was to investigate how the above mentioned replacement by the copolyester hard segment and compensation by the increment of the hard segment ratio affected the mechanical properties of block copolymers.
The results obtained were as follows:
1) As for the melt-spun fibers (T/i_??_Ph-E1540 [50/50]), since the ratio of i_??_Ph increased, their tensile strength and Young's modulus tended to become lower and elasticity greater.
2) The melt-spun fibers whose i_??_Ph ratio ranging from 15.0 to 17.5 wt% exhibited the mechanical properties superior to those of T-E1540 [40/60].
3) For the X-ray diagrams of the drawn and heat-treated fibers, the apparent degree of crystallinity of the hard segment in T/i_??_Ph (82.5/17.5)-E1540 [50/50] was nearly equal to that of T-E1540 [40/60] when their strengths of the interference spots on the equator of the diagram were compared with one another. The particle sizes of crystallites of the former, calculated from the breadth in radians of the diffraction interference at points of half-maximum intensity, were smaller than those of the latter.
4) Further, on the particle sizes, the results observed under the polarizing microscope had the same tendencies as those described in (3), and the uniform dispersion of crystallites of T/i_??_Ph (82.5/17.5)-E1540 [50/50] within the soft segment matrix was also recognized.抄録全体を表示PDF形式でダウンロード (1538K) -
小森 尚志, 牧島 邦夫1976 年 32 巻 6 号 p. T271-T277
発行日: 1976/06/10
公開日: 2008/11/28
ジャーナル フリーGeneral formulae were derived for the estimation of the number of fiber-to-fiber contacts in fiber assemblies with arbitrary distributions of orientation and fiber length. The main result obtained was the mean number of contacts per unit volume of an assembly, nv given by
where I is as follows.
In the above equation, Ω is the density function of orientation, D the radius of the cross section of the fiber, and Lv the total fiber length per unit volume.
Special applications of the general result were reduced to the formulae presented by van Wyk and O. Kallmes.抄録全体を表示PDF形式でダウンロード (462K)
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