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Volume 32, Issue 2
Displaying 1-12 of 12 articles from this issue
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1976 Volume 32 Issue 2 Pages T78-T79
Published: 1976
Released on J-STAGE: November 28, 2008
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1976 Volume 32 Issue 2 Pages P62
Published: 1976
Released on J-STAGE: November 28, 2008
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JISUKE HAYASHI1976 Volume 32 Issue 2 Pages P37-P45
Published: February 10, 1976
Released on J-STAGE: November 28, 2008
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Osamu Ishizuka, Kiyohito Koyama1976 Volume 32 Issue 2 Pages T43-T49
Published: February 10, 1976
Released on J-STAGE: November 28, 2008
JOURNAL FREE ACCESSA melt spinning experiment of polypropylene has been carried out to investigate the crystallization behavior in a running filament by x-ray diffraction curves. The stream diameter is measured as a function of distance from the spinneret by microscopic photograph, and distributions of extensional strain rate and temperature is obtained from the diameter. The results are as follows.
The variation of lattice spacing along the spinning way agrees with the temperature dependence of lattice spacing in bulk sample. The crystalline orientation factor and the fraction of a*-axis oriented crystallite are not changed throughout the crystallization process. An increase in crystallinity is completed within about 0.5 or 1 sec, and the first half of crystallization proceeds under the extensional deformation. On the assumption of isothermal crystallization, the crystallization in melt spinning is described by Avrami equation with n=1. An increase in crystallite size (D040 and D110) calculated from Scherrer equation is similar to that in the crystallinity along the spinning way. Considering the constant thickness of crystallite in the c-axis direction, the crystallite volume turns out to be directly proportional to the crystallinity.
Hence it is found that the orientation of crystallite is determined before the appearance of crystalline diffraction and the crystallization during the melt spinning is governed mainly by crystallite growth.View full abstractDownload PDF (393K) -
TAISUKE ITO1976 Volume 32 Issue 2 Pages P46-P57
Published: February 10, 1976
Released on J-STAGE: November 28, 2008
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Osamu Ishizuka, Kiyohito Koyama1976 Volume 32 Issue 2 Pages T49-T54
Published: February 10, 1976
Released on J-STAGE: November 28, 2008
JOURNAL FREE ACCESSAn experimental study of the correlation between the development of orientation and extensional deformation during the melt spinning of polypropylene has been carried out. The variation of birefringence in the spinning line is divided into three regions. In the first region, the birefringence increases slowly with tensile stress and in the second, beyond a certain extensional viscosity independent of take up velocity, it increases rapidly under constant stress, reaching finally to a saturated value in the last region. The variation of birefringence is so similar to that of the orientation factor corrected for the density.
The relationship between birefringence and tensile stress is expressed by two different straight lines: in polymer melt Δn=8.3×10-11 σ and in taken up filament Δn=7×105σ0.3. Using the extrapolation technique, the point of intersection of two straight lines yields values of σ=4.4×108 dyne/cm, Δn=36×10-3. The former is very similar to the value for the breaking tensile stress during the melt spinning and the latter agrees favorably with the value for the maximum birefringence of polypropylene.
The birefringence results along with the x-ray results were used to separate the birefringence into two parts, one due to noncrystalline liquid orientation and the other due to crystalline orientation along the spinning way. Noncrystalline contribution is minimum at the beginning of crystallization. This may be interpreted in terms of the heat of crystallization.View full abstractDownload PDF (387K) -
Kazuyuki Yabuki, Hiroshi Ito, Toshihiko Ota1976 Volume 32 Issue 2 Pages T55-T61
Published: February 10, 1976
Released on J-STAGE: November 28, 2008
JOURNAL FREE ACCESSPreviously, it was concluded that poly(p-phenylene terephthalamide) (PPT) fibers comprises a number of pillar-shaped micro-fibrills consisting of extended molecular chains. One of the basis for this notion was the fact that the birefringence calculated for the perfectly uniaxial orientation was less, or at least not greater, than the observed for real PPT fibers. In order to clarify this point, the effect from the interference fringe was taken into account and referred to the result of the electron diffraction measurement. The relation between the fine structure and the mechanical properties of PPT fibers was also studied in the light of the S-S hysteresis behavior, the elongation of fiber period and the structural deformations.
The following results were obtained:
(1) Assuming that the orientation of the b-axes of crystals of a PPT is radial in the sheath and random in the core, the calculated and observed birefringence became agreeable.
(2) The high tenacity and the high modulus of PPT fibers are considered due to the extended chain structure.
(3) The remarkable tendency of fibrillization on structural deformation of this fiber, not seen for other synthetic fibers, is also considered to relate to the pillar-shaped micro-fibrill structure. This may lead to poorer fatigue resistance compared with other synthetic fibers, when used as a reinforcement material in rubber.View full abstractDownload PDF (1914K) -
TAKAYUKI MURAYAMA1976 Volume 32 Issue 2 Pages P58-P60
Published: February 10, 1976
Released on J-STAGE: November 28, 2008
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Tomoko Goto, Hazime Murakami, Masamitsu Nagano1976 Volume 32 Issue 2 Pages T61-T66
Published: February 10, 1976
Released on J-STAGE: November 28, 2008
JOURNAL FREE ACCESSQuantitative measurement of the texture of copper filaments which were obtained by the glass conjugated melt spinning was performed and the following results were obtained.
A single (001) fiber texture is observed for the copper filament. Quantitative orientation evaluation of the crystallite of the fiber texture is made by the method of the preferred orientation analysis of the crystalline polymers.
The degree of the orientation distribution of fiber axis increased with the increased tensile stress and decreased with the increasing effect of rapid cooling. In addition to these results, the degree decreases along the diameter direction of copper filament.View full abstractDownload PDF (865K) -
Takashi Tagawa, Toshihide Tabuchi, Masaru Kashima1976 Volume 32 Issue 2 Pages T67-T72
Published: February 10, 1976
Released on J-STAGE: November 28, 2008
JOURNAL FREE ACCESSThe fold content (Cf) of polyethylene, which varies with drawing and/or annealing, was evaluated by IR method described in the previous report.
Polyethylene film having a-axis orientation was drawn to various draw ratios, draw directions and at various temperatures. In the drawing processes, Cf decreases abruptly in the region of draw ratio of 2-3 and gradually decreases with further drawing when drawn along the machine direction. The contents of remaining folds are quite different between the specimens drawn along the machine direction and those drawn transversely to this direction. Cf also decreases with increasing draw temperature when the film is drawn at constant draw ratio. These facts suggest the difference between the deformation processes of the slipping or rotation of lamellae and those of direct unfolding of chains from the lamellae.
In the annealing process, Cf reflects the content of refolding and indicates the differences in the microstructures of the drawn specimen before and after heat treatment.View full abstractDownload PDF (1208K) -
Juzo Hosokawa, Akira Horikawa1976 Volume 32 Issue 2 Pages T72-T78
Published: February 10, 1976
Released on J-STAGE: November 28, 2008
JOURNAL FREE ACCESSThe friction factor (Pressure drop coefficient) λ of the metallic wire was obtained by measuring the drop in pressure at different values of velocities of the air in a given length of a tube with very thin rectangular cross section, in which the surface of the bottom plane was covered with the metallic wires or with the flat model wires set in parallel and evenly.
The relationship between λ and Re (Reynolds Number) plotted directly on the logarithmic scale, was linear below Re_??_ 1000 and started to deviate upward from this point.
At this point, or the critical Reynolds Number Rc, the flow of the air begins to change from laminar to turbulent and the mean velocity of the air corresponds to about 11m/s in actual size of the metallic wire in use. These results are agreed with those shown by the visual observation in the transparent tube in our previous report1).
Comparison between the frictional factor λt obtained from the actual metallic wire and the friction factor λp obtained from the flat model wire as shown in Fig. 5, showed that λt, was 16% larger than λp.View full abstractDownload PDF (1181K) -
Tomoko Goto, Masamitsu Nagano, Masahiro Yamaguchi1976 Volume 32 Issue 2 Pages T80-T82
Published: February 10, 1976
Released on J-STAGE: November 28, 2008
JOURNAL FREE ACCESSThe cooling effect was examined by spouting the ice water into the winding filament in the pyrex glass conjugated melt spinning of stainless steel.
The spun filament were formed in the amorphous state.
With decreasing the cooling, the tensile strength and elongation of the filament increased while the diameter of filament decreased.
From the observation of scanning electron microscope, it was considered that cooling of spun filament induces the micro crack on the surface.View full abstractDownload PDF (1517K)
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