The relation between free volume and relaxation behavior studied by positron annihilation

正电子湮灭研究自由体积与弛豫行为的关系

• 批准号: 10650894
• 负责人: SUZUKI Takenori
• 金额: $ 2.11万
• 依托单位: High Energy Accelerator Research Organization
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1998
• 资助国家: 日本
• 起止时间: 1998 至 1999
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-10650894/
• 关键词: positron annihilation; free volume; radio isotopes; positronium; polymer; relaxation; rotation; glass transtion; 緩和現象; 極低温; 高分子構造の凍結; ポテンシャル; ガンマ転移; ベータ転移; 高分子; 陽電子寿翁; 電子の浅いトラップ; イオン化

Relaxation behavior of polymers has been studied by the thermo mechanical method (TMA) and NMR. Recently positron annihilation lifetime spectroscopy (PALS) has been applied to study the relaxation behavior of polymers. PALS is utilizing the lifetime measurement of positronium (Ps), which is hydrogen like atom composed of positron and electron. From the lifetime of PS, the size of free volume can be deduced. The intensity of the long lived component related to the PS in the free volume can be a good measure to study many factors such as chemical structure, three dimensional structure, radicals, electronic structure, etc.Hence from the intensity we can discuss characteristics of polymers, if we can prepare samples or experimental condition. We have observed the increase in the intensity at low temperature with the elapsed time. This can be explained by the fact that trapped electrons, which are induced by the radiation effect, increase with the elapsed time. The trapped electrons are kept in the potential created among polymer structures because of the freezing of the structure. Increasing the temperature of samples, the intensity gradually decreases and the after minimum, it starts increasing again. This decrease at low temperature is related to the relaxation behavior, which is originated from the movement of polymer structures.

采用热力学方法（TMA）和核磁共振（NMR）研究了聚合物的弛豫行为。近年来，正电子湮灭寿命谱（PALS）被应用于聚合物弛豫行为的研究。PALS正在利用正电子（Ps）的寿命测量，Ps是由正电子和电子组成的类氢原子。从PS的寿命可以推断出自由体积的大小。自由体积中与PS相关的长寿命组分的强度是研究聚合物的化学结构、三维结构、自由基、电子结构等诸多因素的一个很好的指标。因此，如果我们可以制备样品或实验条件，从强度可以讨论聚合物的特性。我们观察到低温下强度随时间的增加而增加。这可以用这样一个事实来解释，即被辐射效应诱导的捕获电子随着时间的流逝而增加。由于结构的冻结，被捕获的电子保持在聚合物结构之间产生的电位中。随着温度的升高，强度逐渐减小，达到最小值后又开始增大。低温下的这种减少与聚合物结构的运动引起的弛豫行为有关。

项目成果

W.Zheng, Y.Kobayashi, K.Hirata and T.Suzuki: "Mobility of positrons in gamma-irradiated polypropylene and polyethylene"Radiation Physics and Chemistry. 51. 269-272 (1998)

W.Zheng、Y.Kobayashi、K.Hirata 和 T.Suzuki：“伽马射线照射的聚丙烯和聚乙烯中正电子的迁移率”辐射物理和化学。

N.Oshima,et al.: "Application of Pulsed Slow-Positron Bean to Polymer" J.Radioaralytical and Naclear Chemistuy. 239. (1999)

N.Oshima 等人：“脉冲慢正电子豆在聚合物中的应用”J.Radioaralytical and Naclear Chemistuy。

T.Hayashi,et al.: "Characterization of Curing Behavior of Cyanic Ester by a Positron-Annihilation Lifetime Technique" Polymer. 40(in Press). 1053-1056 (1999)

T.Hayashi 等人：“通过正电子湮灭寿命技术表征氰酸酯的固化行为”聚合物。

伊藤泰男、鈴木健訓: "An application of the coincidence Doppler spectroscopy for substances of chemical interest"Radiation Physics and Chemistry. (2000)

Yasuo Ito、Takenori Suzuki：“重合多普勒光谱在化学物质中的应用”《辐射物理与化学》（2000 年）。

Kansy J., suzuki t., Ogawa T., and Murakami M.: "Study of poly(methylphenylsilylenemethylene) by elastic thermalization lifetime analythis"Rad. Phys. Chem.. (in Print, 2000).

Kansy J.、suzuki t.、Okawa T. 和 Murakami M.：“通过弹性热化寿命分析研究聚（甲基苯基亚甲硅基亚甲基）”Rad。