Physical Evidence of Stress-Induced Conformational Changes in Polymers
Physical Evidence of Stress-Induced Conformational Changes in Polymers
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DOI：
10.1007/s11340-020-00673-7
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发表时间：
2020-10
影响因子：
2.4
通讯作者：
N. Huynh;G. Youssef
中科院分区：
文献类型：
--
作者：
N. Huynh;G. Youssef
背景聚合物力学与表征是一个活跃的研究领域，人们致力于获得所施加的载荷与高分子链的特定构象运动之间的预测和相关关系。因此，本研究的目的是介绍基于一种新技术的初步结果，该技术利用非侵入性、非破坏性、和非接触太赫兹spectross.MethodsA介质弹性体致动器（DEA）的结构被用作加载机制，以避免模糊的传输太赫兹时域光谱的光束路径。在DEA中，所施加的电压在有源电极区域下产生机械应力，在无源区域中产生深远的拉伸。有限元分析用于建模和模拟DEA，以量化在0 V至3000 V的电压范围内观察点处的诱导应力。此外，引入了一种新的分析技术的基础上的希尔伯特-黄变换，利用时域信号的弹性体膜和藐视所提出的限制由当前国家的最先进的分析techniques.ResultsThe计算结果显示出的有效应力和施加的电压之间的非线性关系。太赫兹时域信号的分析表明，延迟时间和信号峰值幅度的减少，而这些特性是隐含的折射率的变化有关的变化indexofrefractions.ConclusionsIn所有的，结果证据表明的构象变化和施加的机械应力之间的相互关系。
BackgroundPolymer mechanics and characterization is an active area of research where a keen effort is directed towards gaining a predictive and correlative relationship between the applied loads and the specific conformational motions of the macromolecule chains.ObjectiveTherefore, the objective of this research is to introduce the preliminary results based on a novel technique to in situ probe the mechanical properties of polymers using non-invasive, non-destructive, and non-contact terahertz spectroscopy.MethodsA dielectric elastomer actuator (DEA) structure is used as the loading mechanism to avoid obscuring the beam path of transmission terahertz time-domain spectroscopy. In DEAs, the applied voltage results in mechanical stresses under the active electrode area with far-reaching stretching in the passive area. Finite element analysis is used to model and simulate the DEA to quantify the induced stresses at the observation site over a voltage range spanning from 0 V to 3000 V. Additionally, a novel analysis technique is introduced based on the Hilbert-Huang transform to exploit the time-domain signals of the ultrathin elastomeric film and to defy the limits set forth by the current state-of-the-art analysis techniques.ResultsThe computational result shows a nonlinear relationship between the effective stresses and the applied voltage. Analysis of the terahertz time-domain signals shows a shift in the delay times and a decrease in signal peak amplitudes, whereas these characteristics are implicitly related to the change in the index of refraction.ConclusionsIn all, the results evidentially signify the interrelationship between the conformational changes and applied mechanical stress.