• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文学位 >Molecular dynamics in polymers, polymer networks, and model compounds by dielectric relaxation spectroscopy.
【24h】

Molecular dynamics in polymers, polymer networks, and model compounds by dielectric relaxation spectroscopy.

机译：聚合物，聚合物网络和模型化合物中的分子动力学通过介电弛豫光谱法进行。

获取原文
获取原文并翻译 | 示例
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

Segmental dynamics are investigated in model compounds, polymers, and network-forming polymers. Two aspects of these materials are investigated: (1) the role of molecular structure and connectivity on determining the characteristics of the segmental relaxation, and (2) monitoring the variations in the segmental dynamics during network-forming chemical reactions. We quantify the most important aspects of the dynamics: the relaxation shape, the relaxation strength, the relaxation time, and the temperature dependencies of these properties. Additionally, two general segmental dynamics issues of interest are the length-scale and the homogeneous/heterogeneous aspects. A judicious choice of network-forming polymer provides for the determination of an upper bound on the length-scale. A comparison of relaxation characteristics between dynamic light scattering (measuring density fluctuations) and dielectric relaxation spectroscopy (measuring segmental dipolar reorientation) provides one evaluation of the heterogeneity issue. Dipole dynamics in small molecule model compounds show the influence of molecular connectivity on the cooperative molecular response associated with the glass transition. A rigid, nonpolar, cyanate ester network is shown to develop an anomalous relaxation process during crosslinking. A specific local mode of motion is assigned. Additionally, the main relaxation becomes extraordinarily broad during the course of the network formation, due to markedly increased segmental rigidity and loss of configurational entropy.
机译：在模型化合物，聚合物和形成网络的聚合物中研究了段动力学。研究了这些材料的两个方面：（1）分子结构和连通性在确定节段弛豫特性方面的作用，以及（2）监测网络形成化学反应过程中节段动力学的变化。我们对动力学的最重要方面进行了量化：弛豫形状，弛豫强度，弛豫时间以及这些属性的温度依赖性。另外，感兴趣的两个一般的分段动力学问题是长度尺度和同质/异质方面。网络形成聚合物的明智选择为确定长度标度的上限提供了条件。动态光散射（测量密度波动）和介电弛豫光谱（测量分段偶极子重新定向）之间的弛豫特性比较提供了一种对异质性问题的评估。小分子模型化合物中的偶极动力学显示了分子连接性对与玻璃化转变相关的协同分子响应的影响。刚性，非极性氰酸酯网络显示出在交联过程中出现异常弛豫过程。分配了特定的局部运动模式。另外，由于明显增加的分段刚性和构型熵的损失，在网络形成的过程中，主弛豫变得异常宽泛。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号