1998 Fiscal Year Final Research Report Summary
ANALYSIS FOR MOLECULAR MECHANISN OF PHASE TRANSITION AND CRITICAL PHENOMENA IN POLYMER CRYSTALS
| Project/Area Number |
09640483
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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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.ENG.PROFESSOR, 繊維学部, 教授 (60107159)
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| Co-Investigator(Kenkyū-buntansha) |
HASHIMOTO Masato KYOTO INST.TECH.POLYM.SCI.ENG.ASSIST.PROF., 繊維学部, 助手 (00273540)
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| Project Period (FY) |
1997 – 1998
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| Keywords | NYLON 6Y CRYSTALS / VINYLIDENE FLUORIDE-TRIFLUOROETHYLENE COPOLYMER CRYSTALS / SECOND-ORDER PHASE TRANSITION / CRITICAL PHENOMENA IN TWO-DIMENSIONAL SYSTEM / ORDER-DISORDER PHASE TRANSITION / MOLECULAR MECHANISM / PERCOLATIVE PHASE TRANSITION / FERROELECTRICITY OF EVEN-NUMBERED NYLONS |
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| Research Abstract |
There had been no report in the world, which strictly proved appearance of the second-order phase transition 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 was firstly found in the world that the second-order phase transition occurs around 465 K and I MPa in nylon 66 crystal precipitated from the 0.5 wt % solution.
2. On the basis of the strict calculation for the intra- and intermolecular interaction energies, theoretical analysis was performed on the analogy of the Ising model in 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 relative strength between intra- and intermolecular interactions.
3. Such theoretical interpretatio
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n was supported by the experimental results for a series of nylon 6Y crystals.
4. The first-order phase transition was discovered to occur at normal pressure in the as-synthesized nylon 62 crystal.
5. The first- and second-order phase transition was also found in a VDF/TrFE copolymer crystal, which is the second discovery following the nylon 66 case.
6. The experimental fact that the first-order phase transition suddenly appears when the comonomer fraction increases can be explained by the percolation theory, which is the first application of the percolation theory to the phase transition in polymers.
7. The ferroelectricity of even-numbered nylons was firstly discovered on the basis of the study of the field-induced phase transition of the polymer.
These results are 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 transition and this study contributes to new development of polymer physics. Less
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