Synergetic effect of carbon nanofibers and short carbon fibers on the mechanical and fracture properties of epoxy resin

The effects of carbon nanofibers (CNFs) and combinations of CNFs with microsized short carbon fibers (SCFs) on the mechanical and fracture properties of epoxy resin were investigated. The combined use of CNFs and SCFs leads to significant synergy in the mechanical and fracture properties. The composites reinforced with the combined multiscale fillers exhibit much higher modulus, strength and fracture toughness than the composites reinforced solely with either micro- or nanofillers. The mechanisms of such synergism were analyzed by fracture studies using scanning electron microscopy. The release of overstresses near to SCFs by stress transfer and redistribution, realized by CNFs, was traced to the synergistic effects observed.