| Project/Area Number |
01550704
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
高分子物性
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| Research Institution | The Institute of Physical and Chemical Research |
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Principal Investigator |
FURUKAWA Takeo Riken Institute, Biopolym. Phys. Lab., Research Sci., 生体高分子物理研, 研究員 (90087411)
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| Co-Investigator(Kenkyū-buntansha) |
DATE Munehiro Riken Institute, Biopolym. Phys. Lab., Research Sci., 生体高分子物理研, 研究員 (50087409)
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| Project Period (FY) |
1989 – 1990
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| Project Status |
Completed (Fiscal Year 1990)
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| Budget Amount *help |
¥1,800,000 (Direct Cost: ¥1,800,000)
Fiscal Year 1990: ¥200,000 (Direct Cost: ¥200,000)
Fiscal Year 1989: ¥1,600,000 (Direct Cost: ¥1,600,000)
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| Keywords | Digital fourier transform / Dielectric relaxation / Nonlinear dielectric spectra / Nonlinear conductive spectra / Vinylidene cyanide coplymers / Polyvinyl acetate / Polyethylene oxide / 高分子 / フ-リエ変換 |
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| Research Abstract |
We have developed an apparatus for making accurate measurements of non-linear dielectric relaxation spectra. A sinusoidal electric field with minimal distorsion is applied to a sample and fundamental and higher harmonic dielectric displacements are ditected by means of digital Fourier transform. We obtained linear and third non-linear permittivities as a function of frequency in a 0.01Hz-10kHz range. Using this apparatus, we investigated three kinds of polymers ; vinylidene cyanide copolymers, polyvinyl acetate, and ion-conducting polymers.
1. Vinylidene cyanide copolymers, especially with vinyl acetate, have attracted interest past few years because of their very large linear permittivity. Nonlinear didelctric measurements have shown that the third nonlinear permittivity depends upon frequency according to, epsilon_3^*=DELTA epsilon_3/ (1+i omega tau_3) ^3 in accordance with phenomenological prediction. Combined knowledge about DELTA epsilon_1 and DELTA epsilon_3 allow estimates of the
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number and moment of equivalent dipoles. The large permittivities of vinylidene cyanide opolymers are attributed to very large equivalent dipole moments suggesting an existence of strong cooperativity in their molecular motions.
2. Polyvinyl acetate is shown to exhibit deformed nonlinear spectra due to the contribution of electrostriction. Additional measurements of the elastic compliance allow subtraction of this contribution to yield the intrinsic nonlinear spectra which are consistent with those observed for vinylidene cyanide coplymers.
3. Analogous measurements have been extended to ion-conducting polymers including polyethylene oxide and its derivatives. The results are immediately converted into non-linear conductive spectra to enable discussion on conduction mechanisms of such polymers.
On the basis of these results, we have confirmed that the non-linear dielectric spectroscopy in combination with its linear counterpart provides useful information about molecular interaction and dynamics in polymeric systems. Less
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