Numerical Simulations on Piezoresistivity of CNT/Polymer Based Nanocomposites
Numerical Simulations on Piezoresistivity of CNT/Polymer Based Nanocomposites
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DOI：
10.3970/icces.2011.016.057
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发表时间：
2011-04
影响因子：
3.1
通讯作者：
Alamusi;Y. L. Liu;N. Hu
中科院分区：
文献类型：
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作者：
Alamusi;Y. L. Liu;N. Hu
总结在这项工作中，我们提出了一个3维（3D）的数值模型来预测由绝缘聚合物填充的碳纳米管（CNT）的纳米复合材料的压阻行为。这种材料很有希望通过测量其压阻率，即，电阻变化与施加的应变的比率。在这种数值方法中，首次提出了一个三维电阻网络模型来预测纳米复合材料的导电性与大量的随机分散的碳纳米管在零应变状态下。通过关注纳米复合材料的压阻率在很大程度上受相邻CNT之间的隧道效应影响的事实，我们通过在隧道效应的截止距离内添加那些相邻CNT之间的隧道电阻来修改该3D电阻器网络模型，即，在这项研究中，1nm。通过实验验证了该模型预测的电导率。此外，为了分析不同应变水平下纳米复合材料的压阻特性，本文将改进后的三维电阻网络模型与纤维重取向模型相结合，用于跟踪外加应变下纳米复合材料中刚性碳纳米管的取向和网络变化。利用该组合模型对不同应变水平下的纳米复合材料压阻特性进行了迭代预测，并进行了实验验证。一些关键参数，控制压阻行为，如，隧道电流的横截面积，势垒的高度，定向的碳纳米管，和导电性的碳纳米管和其他纳米填料，进行了系统的研究。所得结果对设计具有高灵敏度的纳米复合材料应变传感器具有指导意义。
Summary In this work, we propose a 3 dimensional (3D) numerical model to predict the piezoresistivity behaviours of a nanocomposite material made from an insulating polymer filled by carbon nanotubes (CNTs). This material is very hopeful for its application in highly sensitive strain sensor by measuring its piezoresistivity, i.e., the ratio of resistance change versus applied strain. In this numerical approach, a 3D resistor network model is firstly proposed to predict the electrical conductivity of the nanocomposite with a large amount of randomly dispersed CNTs under the zero strain state. By focusing on the fact that the piezoresistivity of the nanocomposite is largely influenced by the tunnelling effects among neighbouring CNTs, we modify this 3D resistor network model by adding the tunnelling resistance between those neighbouring CNTs within the cut-off distance of tunnelling effect, i.e., 1nm in this study. The predicted electrical conductivities by this modified 3D resistor network model are verified experimentally. Furthermore, to analyze the piezoresistivity of nanocomposite under various strain levels, this modified 3D resistor network model is further combined with a fibre reorientation model, which is used to track the orientation and network change of rigid-body CNTs in the nanocomposite under applied strain. This combined model is employed to predict the piezoresistivity of the nanocomposite iteratively corresponding to various strain levels with the experimental verifications. Some key parameters, which control the piezoresistivity behaviour, such as, cross sectional area of tunnel current, height of barrier, orientation of CNTs, and electrical conductivity of CNTs and other nanofillers, are systematically investigated. The obtained results are very valuable, which can provide a guidance for designing the strain sensor of this nanocomposite with enhanced sensitivity.