Effect of carbon nanofiber dispersion on the tensile properties of epoxy nanocomposites

Vapor-grown carbon nanofibers (CNFs) were dispersed in an epoxy resin using various techniques such as ultrasonication, high-speed mechanical stirring, and the use of solvent, surfactant and higher temperature. The dispersion behavior of CNF in epoxy was studied by optical microscopy and its effect was investigated on the tensile properties of epoxy nanocomposites. Ultrasonication in the presence of surfactant was found to be the best route of dispersion for low nanofiber concentration (0.1 wt%), whereas for higher nanofiber content (0.5 wt% or higher), a combination of ultrasonication and high-speed stirring at 2000 rpm proved to be very effective. Dispersion of carbon nanofibers up to 0.5 wt% using the optimum dispersion technique improved the Young's modulus and tensile strength of epoxy by 35% and 63%, respectively.