Experimental characterization of the quasi-static and dynamic piezoresistive behavior of multi-walled carbon nanotubes/elastomer composites

Abstract

Multi-walled carbon nanotube (MWCNT)/elastomer composites exhibit a piezoresistive behavior, i.e. their resistivity changes when they are subjected to mechanical loading. Thus, these materials can be used as strain or pressure sensors. In this paper, the effect of carbon nanotube weight fraction on the sensitivity and repeatability of the electrical response of multi-walled carbon nanotube/ethylene–propylene–diene monomer composites is investigated, under quasi-static and dynamic compression (using split Hopkinson pressure bars). It was found that multi-walled carbon nanotube weight fraction and the strain rate have a major influence on the piezoresistivity of such composites. Although all samples exhibited a good repeatability of their electrical response under quasi-static cyclic compression, those with a lower multi-walled carbon nanotube weight fraction had a higher sensitivity to strain. An increase in the electrical resistance during compression was observed under both quasi-static and dynamic compression. Reversible movements of multi-walled carbon nanotube in the transverse direction of compression increased the average inter-multi-walled carbon nanotube distance under quasi-static compression, leading to higher values of resistance. After the dynamic tests, the Young’s modulus of the composites decreased by about 45% and the electrical resistance increased a hundredfold, indicating damage induced by dynamic loading.

Prediction of the piezo-resistive behavior of rubber/carbon nanotube nanocomposites under quasi-static compression

“…An electrical current I in the range of 10 µA to 3 mA was input through a linear measurement device. Thanks to this electronic scheme (see [39]) the range of measurement can be adapted by choosing an appropriate input current value. This setup gives the electrical voltage V as output, which in turn is used to calculate the electrical impedance at the macro-scale Z = V /I.…”

“…The Ogden hyper-elastic constitutive model was used. The experimental engineering stress-strain curve σ (ε) (ε is the change in length to original length ratio) was provided by [39]. This enables to determine the material constants µ m and α m .…”

Electrical properties of elastomer‐based composites reinforced with carbon nanotubes—A review

“…In 2007, Bokobza 47 reported that the addition of carbon black (CB) particles may improve the formation of connected networks in elastomeric-based composites reinforced with carbon nanotubes, by bridging isolated nanotubes. 47,165 More recently, Penvern et al 166 manufactured EPDM composites reinforced with both CB and MWCNTs. They also confirmed that carbon black particles act as bonding agents between MWCNTs and the elastomeric macromolecules, which helps obtain homogeneous filler dispersion inside the matrix.…”