| Project/Area Number |
12650884
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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 |
高分子構造・物性(含繊維)
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| Research Institution | KYOTO UNIVERSITY |
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Principal Investigator |
WATANABE Hiroshi Kyoto University, Institute for Chemical Research, Associate Professor, 化学研究所, 助教授 (90167164)
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| Co-Investigator(Kenkyū-buntansha) |
INOUE Tadashi Kyoto University, Institute for Chemical Research, Instructor, 化学研究所, 助手 (80201937)
OSAKI Kunihiro Kyoto University, Institute for Chemical Research, Professor, 化学研究所, 教授 (00027046)
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| Project Period (FY) |
2000 – 2001
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| Project Status |
Completed (Fiscal Year 2001)
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| Budget Amount *help |
¥3,300,000 (Direct Cost: ¥3,300,000)
Fiscal Year 2001: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 2000: ¥2,300,000 (Direct Cost: ¥2,300,000)
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| Keywords | entangled chain / type-A dipole / global chain motion / rheo-dielectric test / tube model / convective constraint release / thermal constraint release / 流動誘起束縛開放機構 / 熱的束縛開放機構 / 絡み合い / 非ニュートン流動 / 非平衡分子運動 / 流動誘電難和 / ポリイソプレン |
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| Research Abstract |
The non-equilibrium motion of entangled type-A polymers under fast flow was investigated rheo-dielectrically. For the type-A linear cis-polyisoprene (PI), the terminal relaxation frequency ω_1 characterizing the chain motion in the shear-gradient direction was found to coincide with the equilibrium relaxation frequency ω_<1,eq>, even at high shear rates γ【similar or equal】10ω_<1,eq> where the significantly non-Newtonian thinning behavior was observed. For a star-branched PI, ω_1 increased with γ only by a factor of 〜 30 %. For both linear and star PI chains, the dielectrically detected chain dimension in the shear-gradient direction decreased just slightly with increasing γ. These results demonstrate that the shear-orientation of the entangled chains is much less significant than that predicted from the classical tube model, lending a qualitative support to the recently proposed convective constraint release mechanism.
In relation to the above difference in the ω_1 of the linear and star PI chains, the equilibrium dynamics of these chains was analyzed in details through comparison of their viscoelastic and dielectric properties. The analysis indicated that the linear chain moves in a dynamically dilated tube (as assumed in the recent models), while the global motion of the star chains cannot be described as the motion along the dilated tube but is dominated by the thermal constraint release (TCR) mechanism. The difference in the ω_1 of the linear and star PI chains is partly related to this large TCR contribution to the star relaxation.
On the basis of the above result, the tube model for the star chains was modified to combine the tube dilation and TCR mechanisms. This refined model gave better description of the equilibrium dielectric data (compared to the original model) without spoiling the excellent agreement with the viscoelastic data. This result suggests a promising direction of further refinement of the model.
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