| Project/Area Number |
06640527
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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 |
物理学一般
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| Research Institution | Kyoto Institute of Technology |
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Principal Investigator |
ITOH Takashi Kyoto Inst.Tech.Polym.Sci. & Tech.Assoc.Prof., 繊維学部, 助教授 (60107159)
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| Co-Investigator(Kenkyū-buntansha) |
KONISHI Takashi Kyoto Inst.Tech.Polym.Sci. & Tech.Professor, 繊維学部, 教授 (70027861)
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| Project Period (FY) |
1994 – 1995
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| Project Status |
Completed (Fiscal Year 1995)
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| Budget Amount *help |
¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1995: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1994: ¥1,600,000 (Direct Cost: ¥1,600,000)
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| Keywords | Even-Even Nylon Crystals / VDF / TrFE Copolymer / First-Order Phase Transition / Second-Order Phase Transition / Specific-Heat Anomaly / Critical Phenomena / Mean-Field Approximation / Ising Model / ナイロン66結晶 / フッ素系共重合体 / 二位相転移 |
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| Research Abstract |
There had been no report in the world, which strictly proved appearance of the second-order phase transition or existence of the critical point in polymer crystals. We planned this project on the basis of our own experimental results that firstly showed the phenomena of the second-order phase transition in nylon 66 and vinylidene fluoride/trifluoroethylene (VDF/TrFE) copolymer crystals. The main results obtained are as follows ;
1. It is necessary to cause the phase transition in even-even nylon crystals that there are 6 CH_2 moiety between NH groups as well as 0 or 6 CH_2 moiety between CO groups in the chain, or vice versa. The phase transition is trasferred to continuous structural change when the number of methylene groups between CO (or NH) groups is more than 6.
2. The 6 CH_2 moiety was found to assume 4 stable states energitically other than the all-trans conformation on the basis of the energy calculation.
3. Theoretical analysis was performed on the analogy of the Ising model in
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rectangular lattice to show that such phenomena is the order-disorder type structural change which has both aspects of phase transition and continuous change due to the intermolecular interaction.
4. The first- and second-order phase transition was also found in VDF/TrFE copolymer crystal, which is second discovery following the nylon 66 case.
5. The mean-field approximation was applied to the copolymer case on the basis of the energy calculation, where the intermolecular interaction was classified into three types. The experimental facts that the transition temperature is decreased with increasing VDF fraction and crystal thickness was firstly explained by the calculated temperature dependence of specific heat.
6) The theoretical analysis also suggested that the electrostatic interaction is necessary to cause the phase transition in the copolymer crystals, and that the copolymer molecule with high molar fraction of VDF has long sequence of VDF groups.
This result is the first discovery and proof of the critical phenomena for polymer crystals in the world, and also the first study which clearly explains the microscopic phase-transition mechanism on the basis of the statistical mechanics, being closely related with the experimental facts.
We believe that we have created a new category in the field of crystalline phase transiton and this study contributes to new development of polymer physics. Less
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