Multi-scale numerical simulations on piezoresistivity of CNT/polymer nanocomposites.
Multi-scale numerical simulations on piezoresistivity of CNT/polymer nanocomposites.
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DOI：
10.1186/1556-276x-7-402
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发表时间：
2012-07-17
影响因子：
--
通讯作者：
Cai Y
中科院分区：
文献类型：
--
作者：
Hu B;Hu N;Li Y;Akagi K;Yuan W;Watanabe T;Cai Y
在这项工作中，我们提出了一个全面的多尺度三维（3D）电阻网络的数值模型来预测由绝缘聚合物基体和导电碳纳米管（CNTs）的纳米复合材料的压阻行为。这种材料由于其高压阻性（定义为电阻变化率除以机械应变）而有望用作高灵敏度的电阻型应变传感器。在这个多尺度的三维数值模型中，三个主要的工作机制，这是众所周知的，以诱导由纳米复合材料制成的应变传感器的压阻，第一次被系统地考虑。它们是：（a）由碳纳米管形成的内部导电网络的变化，（B）相邻碳纳米管之间的隧道效应，和（c）碳纳米管的压阻。本文的数值计算结果与我们以前的实验结果进行了比较，以验证本数值模型。详细探讨了碳纳米管压阻效应对纳米复合应变传感器总压阻效应的影响，并与其他两种机制的影响进行了比较。发现前两种工作机制（即，内部导电网络的变化和隧道效应）对纳米复合材料应变传感器的压阻效应起主要作用，而来自CNT的压阻效应的贡献相当小。目前的数值结果可以提供有价值的信息，设计高灵敏度的电阻型应变传感器制成的各种纳米复合材料的绝缘聚合物基体和导电纳米填料。
In this work, we propose a comprehensive multi-scale three-dimensional (3D) resistor network numerical model to predict the piezoresistivity behavior of a nanocomposite material composed of an insulating polymer matrix and conductive carbon nanotubes (CNTs). This material is expected to be used as highly sensitive resistance-type strain sensors due to its high piezoresistivity defined as the resistance change ratio divided by the mechanical strain. In this multi-scale 3D numerical model, three main working mechanisms, which are well known to induce the piezoresistivity of strain sensors fabricated from nanocomposites, are for the first time considered systematically. They are (a) the change of the internal conductive network formed by the CNTs, (b) the tunneling effect among neighboring CNTs, and (c) the CNTs’ piezoresistivity. Comparisons between the present numerical results and our previous experimental ones were also performed to validate the present numerical model. The influence of the CNTs’ piezoresistivity on the total piezoresistivity of nanocomposite strain sensors is explored in detail and further compared with that of the other two mechanisms. It is found that the first two working mechanisms (i.e., the change of the internal conductive network and the tunneling effect) play a major role on the piezoresistivity of the nanocomposite strain sensors, whereas the contribution from the CNTs’ piezoresistivity is quite small. The present numerical results can provide valuable information for designing highly sensitive resistance-type strain sensors made from various nanocomposites composed of an insulating polymer matrix and conductive nanofillers.