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Volume 10 (1982)
- Issue 4 Pages 147-
- Issue 3 Pages 103-
- Issue 2 Pages 51-
- Issue 1 Pages 1-
Volume 10, Issue 3
Displaying 1-7 of 7 articles from this issue
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Seisuke OKUBO1982 Volume 10 Issue 3 Pages 103-112
Published: September 30, 1982
Released on J-STAGE: November 20, 2012
JOURNAL FREE ACCESSThe shear stress in capillary flow of polymer melts at the wall is discussed. The theoretical result suggests that Bagley's formula holds even if the exit pressure is not negligible in capillary flow of polymer melts. The importance is emphasized of distinguishing the pressure in tne axial direction (driving pressure) from that in the radial direction in cases of flow where primary and secondary normal stress differences N1 and N2, respectively, exist.
Experimentally, N1 and N2 are obtained from the data of mean normal stress difference and the pressure difference between inner and outer walls of the annulus. The magnitude of N2 reletive to N1 is 20~40% for high-density polyethylenes we used. The N2 increases with the square of shear stress at low shear stress, while it does at a rate slightly less when shear stress is above 0.08 MPa.
A simple model of a polymer melt is proposed to explain the normal stress effect and the Barus effect in cases of a steady shear flow and a converging flow. Assuming that the polymer melt consists of numerous flowing units which in turn are aggregates of Voigt elements with balls at their outer ends, we calculate the primary normal [stress difference and swelling ratio. In sofar as our experiments are concerned, the theoretical results show reasonable agreement with the experimental results in both cases of the normal stress effect and the Barus effect.View full abstractDownload PDF (1674K) -
Yoshiyasu SATO1982 Volume 10 Issue 3 Pages 113-122
Published: September 30, 1982
Released on J-STAGE: November 20, 2012
JOURNAL FREE ACCESSFrom a brief historical survey on molecular theories (based on the network model) and phenomenological theories (the theory of elasticity of finite deformation) for rubberlike elasticity, a fact is confirmed that although the molecular theory established an analytical system of 0th-order to 2nd-order approximate theories in 1952, the phenomenological theory had been left incomplete till 1969 due to lack of further approximations than 0th-order (neo-Hookean elasticity) proposed in nineteen-forties. The analytical approximate equations of 0th-order to 2nd-order derived in a previous paper for making up an analytical system of approximation in the phenomenological theory are verified to be similar in shape corresponding to those in the molecular theory. In this verification, a more general molecular theory is derived in a more organized form. It is confirmed that the shape of the approximate equation of each order is unique and it can never have another shape. It is also pointed out that the similarity in shape between corresponding equations in the molecular theory and the phenomenological theory comes from each kinematic relation with similar shape, and that the uniqueness of the shape of every equations in the molecular theory is also owing to the kinematic relation.
An attempt is made to compile the two kinds of theories, the phenomenological and molecular theories, into a unified theory, on the basis of one-to-one correspondence due to similarity of the shape between the equations in the two kinds of theories.View full abstractDownload PDF (1786K) -
Elongational Viscosity Measurements on AS and ABS by an Extensional RheometerYoichiro SAITO1982 Volume 10 Issue 3 Pages 123-127
Published: September 30, 1982
Released on J-STAGE: November 20, 2012
JOURNAL FREE ACCESSFor measurements of extensional properties of AS and ABS, an extensional rheometer of vertical type with a couple of rotational clamps was developed. Measurements were carried out under wide ranges of temperature (120~150°C) and strain rate (2.5×10-3~2.8×100 sec-1).
In the higher strain-rate region, elongational viscosities for both AS and ABS increase rapidly with time, while in the lower strain-rate region, the extensional behavior of two polymers results in a remarkable difference. That is, elongational viscosities of AS approach a constant level which is three times the zero-shear viscosity according to the Trouton relationship. A much stronger increase of viscosity of ABS sample in comparison with AS sample was observed at lower strain-rates. The differences of the elongational behavior of two polymers at the lower strain-rates are related to the shear viscosity at the lower shear rates.
Time-temperature superposition can be applied to the strain rate dependence curves of the elongational viscosity at constant strains measured at different temperatures. The temperature dependence of the shift factor aT, for the elongational viscosity agrees well with that of the shear viscosity, and is well-expressed by the WLF equation.View full abstractDownload PDF (693K) -
Dynamic Viscoelastic and Extensional Properties of ABSYoichiro SAITO1982 Volume 10 Issue 3 Pages 128-134
Published: September 30, 1982
Released on J-STAGE: November 20, 2012
JOURNAL FREE ACCESSDynamic viscoelastic properties and elongational viscosities were measured for seven ABS samples having different morphorogy of rubber particles and molecular weights of matrix AS. The elongational viscosity exhibits a linear behavior in a range of strain less than 0.5, regardless of the molecular characteristics of ABS samples. In a region of strain higher than 0.5, the elongational viscosity strongly depends on the morphology of rubber particles and the molecular weights of the matrix AS. For the samples having higher modulus Gpa of the second plateau, the stronger increase of the elongational viscosity with the time is observed in the region of lower strain rate. For ABS which exhibits a linear viscoelstic behavior in the region of lower frequency, however, the elongational viscosity at small strain-rates seems to approach a constant value which is equal to 3η0. From these results it can be concluded that the time dependence of the elongational viscosity in the region of lower strain rate is qualitatively related to the dynamic viscoelastic behavior in the region of lower frequency.
For ABS samples having the same rubber particles, the stress-strain rate curves for different molecular weights can be superposed onto those for reference ABS by horizontal shift to give a master curve. The molecular weight dependence of the horizontal shift factor is 4.0, somewhat larger than 3.5.View full abstractDownload PDF (929K) -
Recoverable Strain and Deformation of Rubber Particles of ABSYoichiro SAITO1982 Volume 10 Issue 3 Pages 135-139
Published: September 30, 1982
Released on J-STAGE: November 20, 2012
JOURNAL FREE ACCESSThe recoverable strain and the deformation of dispersed rubber particles of ABS were examined by means of an extensional rheometer designed for investigations of the elongational viscosity. The recoverable strain εR strongly depends on the stretching temperature and the applied strain rate as well as the total strain. With decreasing temperature, or with increasing strain rate, the εR seems to approach a constant level which is equal to the total strain. Time-temperature superposition can be applied to the strain rate dependence curves of εR at constant total strains measured at different temperatures. The shift factor ear agrees well with the values calculated by the WLF equation, log aT=-8.86(T-137)/(101.6+T-137). The deformation of rubber particles is closely related with εR. And its dependency on the total strain, temperature and strain rate is the same in the case of εR. The modulus of rubber particles obtained by σ=G (λ2-1/λ) were about twice of the rubbery plateau moduli of the ABS sample.View full abstractDownload PDF (1151K) -
Yoshio SHIRASAKI, Tetsuya TATEISHI, Yutaka MIYANAGA1982 Volume 10 Issue 3 Pages 140-142
Published: September 30, 1982
Released on J-STAGE: November 20, 2012
JOURNAL FREE ACCESSMechanical properties of the various regions of cancellous bone and cartilage-cancellous bone composite of the human acetabulum were investigated.
Their elastic moduli and strengtns were almost the same as those of the femoral head, while their phase lags were lower than those of the femoral head.
Their regional difference of the mechanical properties was not so much as in the femoral head. This fact was considered to depend on the difference of the loading condition between the acetabulum and the femoral head.
Dynamic behavior of the acetabulum was also studied by a compression test.View full abstractDownload PDF (405K) -
Hiroshi WATANABE, Shinobu YAMAO, Tadao KOTAKA1982 Volume 10 Issue 3 Pages 143-146
Published: September 30, 1982
Released on J-STAGE: November 20, 2012
JOURNAL FREE ACCESSRheological properties of mixtures of a styrene-butadiene (SB) diblock copolymer dissolved in a low-molecular-weight homopolybutadiene (hB) were examined. In the mixtures, the SB molecules aggregate and form micelles with S cores and B cilia because of the microphase separation between the two components. When the SB content exceeds a certain critical value, the storage and loss moduli of the mixture begin to show a plateau in a low frequency region, which is often called the second plateau and is attributed to some slow relaxation processes. The slow relaxation process found in this particular system appears to be due to the retarded motions of the ciliary B chains caused by the entanglements between the neighboring micelles. This idea may be supported by the fact that the critical concentration at which the second plateau emerges coincides with the concentration at which the micelles begin to contact and their ciliary B chains overlap with each other. Entangled ciliary B chains with one end anchored on a stiff S core should have long relaxation times.View full abstractDownload PDF (531K)
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