Modeling of the piezoresistive behavior of carbon nanotube/polymer composites during stress relaxation

The resistance change of carbon nanotube (CNT)/polymer composites during stress relaxation depended strongly on the CNT concentration and aspect ratio. At low concentration, the resistance of the composites increased regardless of aspect ratio of CNTs as relaxation progressed, while the relaxation modulus accordingly decreased. This trend changed with CNT concentration. To investigate the mechanism, a new resistor model was developed based on the number of contacts between CNTs within tunneling distance of each other. Simulations revealed that when the number of contacts between CNTs is insufficient to form multiple conducting pathways, the increased tunneling resistance has more influence on the overall resistance, leading to the increased resistance. Finally, the proposed resistor model was used to qualitatively explain the resistance change of the composites at different CNT concentration and aspect ratios during tensile test, demonstrating its validity.

Automated summary

The resistance change of carbon nanotube (CNT)/polymer composites during stress relaxation is strongly influenced by CNT concentration and aspect ratio. At low concentrations, the resistance increases regardless of CNT aspect ratio as relaxation progresses. A new resistor model based on the number of contacts between CNTs within tunneling distance was developed to explain this phenomenon, showing that insufficient contacts lead to increased tunneling resistance and overall resistance in the composites. This model was then used to qualitatively explain the resistance change during tensile tests, demonstrating its validity.