Dielectric Behavior of cis-Polyisoprene in Carbon Dioxide under High Pressure
Dielectric Behavior of cis-Polyisoprene in Carbon Dioxide under High Pressure
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高压下二氧化碳中顺式聚异戊二烯的介电行为
DOI：
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发表时间：
2007
期刊：
影响因子：
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通讯作者：
M. Ohshima
中科院分区：
文献类型：
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作者：
Yumi Matsumiya;Tadashi Inoue;H. Watanabe;S. Kihara;M. Ohshima
对顺式聚异戊二烯(PIP)在二氧化碳(CO2)中的高压介电性能进行了测量。随着压力的增加，CO2在PIP中的溶解更多，这种溶解预计会影响链的动力学。在我们的实验窗口中，A型偶极子平行于其主干的PIP链表现出反映其全局运动的介电色散。随着二氧化碳压力的增加，这种色散向更高的频率移动。时间-CO2压力叠加效果较好，这表明CO2加速了链的全球运动，在空间上和沿着链主干没有任何不均匀。这种叠加的垂直移动因子(强度移动因子)给出了PIP中的二氧化碳浓度。在相同的浓度范围内，从水平位移因子(频移因子)来评价CO2的塑化能力略大于十四烷。即使在超临界状态下(压力为10 Mpa)，CO2的塑化能力也没有发现特殊之处。
Dielectric measurement was conducted for cis-polyisoprene (PIP) in carbon dioxide (CO2) at high pressures. CO2 is dissolved in PIP more with increasing pressure, and this dissolution is expected to affect the chain dynamics. In our experimental window, the PIP chains having type-A dipoles parallel along their backbone exhibited the dielectric dispersion reflecting their global motion. This dispersion shifted to higher frequencies with increasing CO2 pressure. Time - CO2 pressure superposition was found to hold well, which suggests that the global motion of the chain is accelerated by CO2 without any heterogeneity in space and along the chain backbone. The vertical shift factor (intensity shift factor) for this superposition gave the CO2 concentration in PIP. The plasticizing capability of CO2 evaluated from the horizontal shift factor (frequency shift factor) was found to be a little larger than that of tetradecane in the same range of concentration. No peculiarity was found for plasticizing ability of CO2 even in the supercritical state (at a pressure of 10 MPa).