A Novel Strategy to Achieve Enhanced Reinforcement and Decreased Damping in CNT-Nanocomposites

In recent decades, polymer-carbon nanotube (CNTs) composite materials have attracted much attention for their potential applications in unique lightweight materials with distinctly superior mechanical properties. For structural applications, high strength can be delivered and conveniently tuned in nanocomposites by guaranteeing a good load-transfer at the CNT/polymer interfaces which is conventionally achieved with the help of complex chemical functionalization approaches.

In this paper, the mechanical properties of Nickel-coated carbon nanotube (Ni-CNT) reinforced Polyamic acid- nanocomposite (Ni-CNTs /PAA) and (CNTs/PAA) arepresented in terms of material rigidity and damping capacity. The Ni nanoparticles on the CNTs outer walls, help to induce an interlocking mechanism at the CNTs/matrix interface. A significant Elastic modulus increase is thus observed for this type of samples. On the other hand, the Ni-CNTs/PAA nanocomposite, decreases its damping capacity when compared with bare CNTs/PAA nanocomposite. It is worth noting that the recorded rigidity increase and damping decrease is reached despite the significantly smaller amount of CNTs (40% lower weight fraction) contained in the Ni-coated samples. The investigated nanocomposite types were in fact conceived with the same total weight, thus with the same amount of filler without taking into consideration the higher weight of Ni nanoparticles. The results here reported proof the concept that when metal nanoparticles coat the CNTs outer walls, an important improvement of the CNTs-matrix load transfer can be reached without the need to undergo into complex CNTs functionalization procedures. This is an advantage since chemical functionalizations typically have the drawback of introducing defects on the CNT walls.