Nano/micro multiscale hybrids with carbon nanotubes (CNTs) grown on the Al2O3 microparticles, SiC microplates or graphene nanoplatelets (GNPs) could serve as multifunctional reinforcements in the composites. The CNTs generally form into symmetric six-orthogonal branches on the spherical Al2O3, but vertically align on the flat surfaces of the SiC and GNP. The introduction of hybrids into the epoxy matrix endows uniform dispersion of CNTs as well as improved interfacial interaction between the reinforcements and matrix. Significantly enhanced mechanical properties of the composites were achieved at low hybrid concentration. The in situ electrical resistance of the composites initially increases to its maximum value and then begins to decrease with the appearance of irreversible deformation, which is different from the pristine CNTs filled composites only with monotonic increase of the resistance until their catastrophic fracture. The mechanical and self-sensing behaviors of the composites are found to be highly dependent on CNT aspect ratio, organization and the substrates. Besides, the introduction of hybrids into the traditional fiber-reinforced composites shows great promise in development of the high-performance multiscale composites. The epoxy matrix is toughed by the well dispersed hybrids at low fraction, resulting in improved flexural and thermomechancial properties. Besides, the conductive networks provided by the hybrids could be utilized as in situ damage sensors to monitor the damage evolution in the glass fabric/epoxy composite laminates under tensile loading.
