54th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference
8 - 11 April 2013, Boston, Massachusetts

AIAA 2013-1731

Computational Micromechanics Analysis of Electron Hopping Induced Piezoresistive Response in Carbon Nanotube-Polymer Nanocomposites

Adarsh Chaurasia and G. D. Seidel
Virginia Polytechnic Institute and State University, Blacksburg, VA, 24061-0203, USA

In this study, a multiscale micromechanics based computational model is developed to capture the eect of electron hopping induced formation/disruption of conductive paths at the nanoscale which govern the eective macroscale conductive and piezoresistive response of the CNT-polymer nanocomposite. The local nanoscale conductivity at the nanoscale is allowed to evolve by tracking the position of the nanotubes under applied deformations and modifying the conductivity of the intertube region depending on the relative proximity of individual pairs of nanotubes. The formation and disruption of the high conductivity bands are highly dependent on the applied strain and yield odd microstructural symmetries for the eective electrical properties, emphasizing on the need of a computational microme- chanics model. The eect of local CNT volume fractions and maximum electron hopping range on the eective macroscale gauge factors is studied for dierent cases of microstruc- ture morphology i.e. CNT-polymer nanocomposites uniformly dispersed aligned CNTs and aligned/randomly oriented microscale bundles composed of aligned CNTs. Random orien- tation of macroscale bundles is taken into account using micromechanics based techniques by averaging over a discrete number of orientations of microscale bundles in a consistent manner. The results presented herein indicate that the eective gauge factors follow a strain dependent nonlinear response with asymmetry on application of tensile/compressive strains. In addition, the eective gauge factors were observed to be smaller for a mi- crostructure with aligned microscale bundles as compared to randomly oriented microscale bundle. The gauge factors obtained from the current work are of comparable magnitude with those reported in the literature based on experimental investigation indicating that electron hopping could be the dominant mechanism governing the macroscale piezoresistive response of CNT-polymer nanocomposites.