It also contains more reactive
carbon edges that can be functionalized to interact with the matrix.
This facilitates filler dispersion and interfacial stress transfer. In particular,
the unique structure of stacked-cup CNF, which is composed
of helically coiled graphene sheets with weak p–p interactions
between stacked layers, had been demonstrated to impart significant
toughening effect in epoxy systems [6,9,10]. Under impact
the weak p–p interactions between the stacked graphene layers
may be overcome to dissipate significant amounts of energy