Highly dispersed aramid nanofiber-reinforced epoxy nanocomposites by the sequential solvent-exchange method

Aramid nanofibers have recently been used as novel reinforcing materials to overcome the limitations of epoxy resin because of their superior strength and toughness. Until now, aramid nanofibers were hybridized into the epoxy resin by adding water into an aramid nanofiber solution to obtain free-standing powders. Unfortunately, such a water-based method for inducing the gelation hinders high-level dispersion due to the re-agglomeration of the nanofibers by protonation. This study presents a novel technique utilizing a solvent-exchange method to maximize the dispersion degree of aramid nanofibers, thereby increasing the mechanical properties of epoxy nanocomposites. The mechanical properties of aramid nanofiber-reinforced epoxy nanocomposites by the solvent-exchange method were improved significantly (3.4 GPa in Young's modulus and 90.0 MPa in tensile strength – improvements of 28.8% and 27.7%, respectively) although a high viscosity epoxy resin (bisphenol-A type) was considered. Therefore, the suggested solvent-exchange method is an efficient manufacturing process to produce highly dispersed aramid nanofiber/epoxy nanocomposites.