Enhancement and Characterization of Carbon Nanotubes Dispersion in Epoxy Resin for Structural Applications
Résumé
Carbon nanotubes (CNT) are promising nanofillers for the development of polymer composites with multiple enhanced properties. It has been long recognized that their potential could not be fully exploited without achieving their good dispersion in the matrix. In the literature, different dispersion instruments were used at the laboratory scale (ultrasonic processor, high shear mixer ...) to disperse CNT in liquid matrices. The use of a dispersing agent can facilitate the dispersion. The most commonly used are surfactants (SDS or NaDBBS) and polymers like PmPV and PVP. This work will show that the combination of the right dispersion instrument with a suitable dispersing agent can improve the dispersion of multiwall carbon nanotubes in epoxy resin. Due to van der Waals interactions, CNT are in aggregate form with size up to hundreds of 2m. In this study, light transmission optical microscopy was used to evaluate the size and distribution of these aggregates. Dielectric spectroscopy and shear rheology were performed in order to detect and evaluate any enhancement in dispersion. In fact, when the aggregates are broken during dispersion, CNT spread into the matrix to form a complex interconnected network. It is thus expected that the electrical conductivity (when the dispersion quality overcomes the reduction in length of the CNT) and the viscosity increase.