The role of trapped solvent on rheological and mechanical properties of multi-walled carbon nanotube/epoxy nanocomposite

In this study, carbon nanotube/epoxy nanocomposites were prepared via re-dispersion of ultrasonically dispersed CNTs in ethanol/Pluronic F127 solution. The ethanol solvent was evacuated from the epoxy nanocomposite during its re-dispersion in epoxy matrix and further using a vacuum oven at high temperature. The dispersion state of CNT in ethanol solvent and epoxy matrix was assessed using different rheological measurements as well as UV-Vis spectroscopy. Mechanical properties of the prepared nanocomposites were measured in compression mode. The viscosity upturn and enhanced storage modulus at low frequencies indicated the well dispersion of CNTs inside the epoxy matrix, while the compressive modulus of the corresponding nanocomposite was decreased compared to unprocessed cured epoxy. Based on these results, It was concluded that while using low viscosity solvents is curtail for propagation of ultrasonic waves and hence well dispersion of CNTs in final products, the trapped solvent will dramatically decrease the mechanical properties of the epoxy/CNT nanocomposites mainly due to its negative effects on epoxy curing mechanism.