Three-dimensional nano-structural design for enhanced damping performance of carbon fiber reinforced polymer composites with balanced mechanical performance

Damping performance is important in the structural design of carbon fiber reinforced polymer (CFRP) composites in many engineering fields. According to the various modification methods, a challenge of achieving high damping performance of CFRP is the conflict between damping and mechanical properties. To overcome this difficulty, in this work, we pioneered a three-dimensional hybrid nanostructure on the surfaces of the carbon fibers, which helped avoid the nanofiller dispersion issue in these CFRP composites. That is, graphene oxide (GO) sheets are first coated on the carbon fiber fabrics by electro-deposition, then carbon nanotubes (CNTs) are grafted onto the GO by the ethanol pyrolysis flame method. Experimental results show that this hybrid nanoarrangement possesses a synergistic damping enhancement [i.e., GO-CNTs (+130%) > CNTs (+24%) + GO (+83%)]. Specifically, the orientated GO nanosheets dissipate mechanical energy through interlayer sliding under the shear stress which exists at the fiber/epoxy interphase, while the well-dispersed CNTs enhance the energy dissipation through CNT/epoxy interfacial friction and facilitate more effective stress transfer at the fiber/ epoxy interphase. Molecular dynamics simulations also validate that this hybrid nanostructure forms a robust energy dissipation network, yielding a superior damping performance. Moreover, the GO-CNT modified CFRP composite maintains a balance of mechanical properties, displaying increased tensile strength (+12%), marginally reduced interlaminar shear strength (-5.0%), and enhanced mode I interlaminar fracture toughness (+35%) owing to the effect of CNT bridging in the CNT/epoxy interlayer.