Comprehensive analysis on the electrical behavior of highly stretchable carbon nanotubes/polymer composite through numer
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ARTICLE Comprehensive analysis on the electrical behavior of highly stretchable carbon nanotubes/polymer composite through numerical simulation Xiang Fu,a) Ahmed M. Al-Jumaily, and Maximiano Ramos Institute of Biomedical Technologies, Auckland University of Technology, Auckland 1010, New Zealand
Yi-Feng Chen School of Information Engineering, Wuhan University of Technology, Wuhan, Hubei 430070, China (Received 19 February 2018; accepted 6 August 2018)
The elastic polymer composite embedded with carbon nanotubes (CNTs) is an ideal candidate for stretchable and flexible sensor fabrication due to the perfect combination between the excellent properties of CNTs and the high stretchability of the elastomer. A cube model of nanotube/ polymer composite is constructed to comprehensively and theoretically analyze its electrical behavior, which is dominantly governed by the CNT network. The aspect ratio and alignment of CNTs significantly influence both the percolation threshold range and the electrical conductivity; however, the electrical conductivity of CNTs has little impact on the percolation threshold. The piezoresistivity of the composite is not only governed by the property of CNTs but also by the mechanical property of the polymer matrix, including the Poisson’s ratio and alignment of CNTs. The specific reasons why the composite resistance rises when it is stretched are investigated. Finally, one optimizing suggestion is given for making the CNTs/polymer composite with high sensitivity.
I. INTRODUCTION
Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/jmr.2018.301
Although recently many numerical and theoretical studies aimed at understanding the principle of electrical characteristics, there are few studies comprehensively investigating the piezoresistivity at and after percolation threshold through a realistic composite model.7,8 Moreover, to determine percolation threshold, the empirical percolation method and power law are currently the typical ways to analyze the electrical conductivity and piezoresistivity.9,10 To some extent, it is not sufficient to exhibit a clear view of the electrical conductivity variation along with the increasing of the conductive filler concentration. In particular, the critical percolation threshold is not a definite value, but a range of values. Furthermore, in the range of values, the electrical conductivity varies quite significantly. This problem was neglected by pioneering work. Hence, the range of percolation threshold should be further investigated. Amini et al. merely proposed the concentration close to the percolation threshold that would give the composite a higher sensitivity but did not specify whether the value should be more than the percolation threshold or not.11 Hu et al. have developed a 3D CNTs/polymer model to analyze its electrical behavior, while they did not further investigate piezoresistivity.12 They only pointed out the sensitivity which primarily depends on the tunneling resistance and the ratio of the tunneling resistance to total r
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