Open Access

ARTICLE

Numerical Simulations on Piezoresistivity of CNT/Polymer Based Nanocomposites

Alamusi¹, Y.L. Liu¹, N. Hu^1,2

1 Chiba University, Chiba, Japan
2 Chongqing University of Science & Technology, Chongqing, China

Computers, Materials & Continua 2010, 20(2), 101-118. https://doi.org/10.3970/cmc.2010.020.101

Abstract

In this work, we propose a 3 dimensional (3D) numerical model to predict the piezoresistivity behaviors 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 sensor is largely influenced by the tunneling effects among neighboring CNTs, we modify this 3D resistor network model by adding the tunneling resistance between those neighboring CNTs within the cut-off distance of tunneling effect, i.e., 1.0 nm in this study. The predicted electrical conductivity by this modified 3D resistor network model is verified experimentally. Furthermore, to analyze the piezoresistivity of the nanocomposite sensor under various strain levels, this modified 3D resistor network model is further combined with a fiber 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 behavior, 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 guidance for designing the strain sensor of this nanocomposite with enhanced sensitivity.

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Keywords

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