On the use of dielectric spectroscopy for the real time assessment of the dispersion of carbon nanotubes in epoxy

In this work, we report the on line monitoring of the dispersion of carbon nanotubes in a typical aerospace epoxy system. The dispersion quality is well known to dominate all the properties of the nanocomposite. Process monitoring was performed using a dielectric spectroscopy system to measure the evolution of the impedance of the mixture during ultrasonication. Interdigital sensors were employed as flat capacitors immersed in the mixture. The evolution of the dispersion process was accurately monitored via the changes in the real and the imaginary parts of the impedance. Furthermore, the distinct stages of the dispersion process were modelled using an equivalent circuit which was found to accurately represent the involved phases and their interaction during dispersion process. Overall, this work demonstrates how dispersion control may become possible through real-time in situ measurement of the dielectric response from the system, analysis of its main components and identification of the significant features.