The concept of carbon nanotube interlayer was successfully introduced to carbon fiber/epoxy composites. This new hybrid laminated composites was characterized by Raman spectroscopy, X-ray diffraction, scanning electron microscopy and tensile tests. An increase on peak stress close to 85% was witnessed when CNTs interlayer with 206.30 mg was placed to carbon fiber/epoxy laminates. The failure mechanisms are associated to CNTs distribution between and around carbon fibers. These CNTs are also responsible for crack bridging formation and the increase on peak stress. Initial stiffness is strongly affected by the CNT interlayer, however, changes on stiffness is associated to changes on nano/micro-structure due to damage. Three different behaviors can be described, i.e. for interlayers with ≈ 60 mg of CNT the failure mode is based on cracks between and around carbon fibers, while for interlayers with CNT contents between 136 mg and 185 mg cracks were spotted on fibers and inside the CNT/matrix mix. Finally, the third failure mechanism is based on carbon fiber breakage, as a strong interface between CNT/matrix mix and carbon fibers is observed.

Two different carbon based nanostructures, multiwall carbon nanotubes and multilayered graphene, were incorporated to carbon epoxy laminated. X-ray diffractometry indicates that graphene blocks are formed by approximately 66 layers of graphene. Scanning electron microscopy observation revealed that graphene blocks are located mainly near to the fiber/matrix region, while carbon nanotubes are dispersed into the matrix. These nanostructures can affect significantly the overall mechanical properties, in special the tensile and bending strength, which are direct, related to the internal stress distribution and failure modes. No significant stiffness changes were observed in both, tensile and bending, tests, while tensile strength were improved by 19% with 2 wt.% addition of graphene. The carbon nanotube + multi-layer graphene nanostructures need to be improved as some segregated areas between the two components were observed. Nevertheless, the results from those nano-modified specimens were all higher than the one without nanoparticle dispersion for tensile loads. When the bending tests are analyzed a different scenario is noticed. The nanostructure scattering has high influence into the laminate composite overall behavior. Matrix failure is dominant for those specimens with irregular dispersal, while a fiber failure seems to be an evidence of nanostructure uniform distribution.