Statistical Analysis of Effective Piezoresistivity of Carbon Nanotube Reinforced Polymer Nanocomposites from Electron Tunneling Effects

摘要

CNT doped polymers exhibit piezoresistivity due to a combination of phenomena occurring at the nanoscale and microscale length scales. These effects manifest into an observable piezoresistive response in macroscale specimens. One of these effects - electron tunneling, is a significant contributor to the overall piezoresistive response and acts in the nanoscale regime. It is a quantum phenomenon where electrons jump across insulating dielectric media from one conductive domain to another. The extent of the derived piezoresistivity due to electron tunneling depends upon various factors such as concentration of CNTs, size and shape of CNTs, orientation and distribution of CNTs and the properties of the CNT and the surrounding polymer. This study aims to understand the variation in the piezoresistive effect derived from the electron tunneling effect by analyzing each of the aforementioned factors individually and as groups. Several nanoscale computational domains or RVEs (representative volume elements) are generated for each combination of factors selected through a randomized 2D nanocomposite configuration generation algorithm. The generated RVEs are analyzed using a 2D quasi static electromechanical finite element model under various conditions of loading and electrode placement to fully populate the effective piezoresistivity strain coefficient tensor Π_(ijkl) Large data sets gathered from analysis of several configurations were used to perform statistical significance testing of the derived piezoresistive coefficients and their dependence on the suggested factors. Conclusions from this study also aided in establishing expected variation in conductivity and piezoresistivity values for CNT doped polymers for different configurations.