Temperature dependence of single-walled carbon nanotube migration in epoxy resin under DC electric field

Electric fields have been shown to induce orientation of CNTs in a polymer matrix along the direction of the applied field. When using a DC field, the CNTs also migrate between the two electrodes, resulting in a nonuniform CNT concentration across the composite sample and impacting the strengthening effect gained from the CNT alignment. In this study, we applied a DC electric field to a single-walled carbon nanotube (SWCNT)/epoxy solution and investigated the migration kinetics at different temperatures (34.0–56.6 °C) by tracking the real-time changes of SWCNT concentration. The SWCNTs were found to migrate from the negative electrode to the positive electrode at a constant speed. The rate of CNT migration increases with temperature and follows an Arrhenius relationship. The activation energy (83.3–87.7 kJ/mole) was comparable to the activation energy for the viscous flow of the neat epoxy, indicating the viscosity of the polymer melt is the main factor affecting the migration. The migration process and the resulting CNT concentration gradient across the sample are a function of temperature and time enabling control of the spatial distribution of the CNTs and the selective enhancement of electrical, mechanical and thermal properties of CNT/polymer composites.