Aligned graphene platelets for the detection of crack extensions in nanocomposites

Nanocomposites with aligned graphene were fabricated and used to detect crack extension. Graphene were dispersed into epoxy resin through mechanical mixing followed by the sonication. To align the graphene, the graphene and epoxy mixture was subjected to an electrical field for 20 min. When the graphene loading was close to the percolation threshold (0.15 wt%), the network was established and the electrical conductivity of the nanocomposite dramatically increased. Three-point bending tests were conducted on single edge notch bending (SENB) specimens with the graphene aligned perpendicular to the loading direction. During the tests, the electrical resistance of the specimens was measured using a high-resistance meter. The results indicated that the resistance of the samples increased markedly prior to crack extension. Thus, aligned graphene can be employed to detect crack extensions.