2003 Fiscal Year Final Research Report Summary
Molecular Motion of Polymers under Supercritical Carbon Dioxide
| Project/Area Number |
14550843
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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 | Tokyo University of Agriculture And Technology |
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Principal Investigator |
SAITO Hiromu Tokyo University of Agriculture And Technology, Faculty of Technology, Associate Professor, 工学部, 助教授 (90196006)
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| Project Period (FY) |
2002 – 2003
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| Keywords | poly(methyl methacrylate) / molecular motion / plasticization / conformation / local ordering / 分子形態 / 局所的秩序性 |
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| Research Abstract |
In order to deeply understand the molecular motion of polymers under supercritical C0_2, we carried out in-situ measurements of dielectric loss e" in PMMA over a wide frequency f range at various temperatures under CO_2. The PMMA under ambient pressure shows an Arrhenius behavior and a bend at around Jig. The bend may arise from the change in the mode of motion at T_g ; i.e., the motion above T_g is the αβ process while that below Jig is the β process. The PMMA under CO2 also exhibits an Arrhenius behavior and the plots also bend. The bending temperature shifts to lower temperature with increasing CO_2 pressure. This may be ascribed to the decrease of Jig with increasing CO_2 pressure due to the plasticizing effect by CO_2. The interesting result here is that the f_<max> below T_g also becomes higher with increasing CO_2 pressure, suggesting that the local motion such as the side group rotation is also accelerated by the plasticizing effect. After injecting C0_2, the shift of the peak position was leveled off and the shape of the peak became narrower with time, suggesting that the density fluctuation is homogenized with time and the acceleration of the molecular motion is leveled off due to saturation of the absorbed CO_2 in PMMA. The peak height increases with time while the peak position remains constant. The peak height under CO_2 became 2 times larger than that under ambient pressure having the same f_<max>. The increase of the peak height may be ascribed to the acceleration of the cooperative motion between adjacent chains due to a change in chain conformation from random coil to a locally ordered state.
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Research Products
(14 results)
