The Efficiency of Carbon Nanotubes in Reinforcing Structural Polymers

Abstract

The carbon nanotube efficiency index in a nanocomposite is introduced as the ratio of the load carried by carbon nanotubes (CNTs) at a given average deformation of a matrix to the maximum possible load that can be transferred to the nanotubes at this deformation. The best published results on polymer strengthening with an assessment of CNT efficiency are reviewed. Analysis of the data in publications shows that the upper boundary of CNT efficiency is reached in polymers if a network of interconnected nanotubes is formed inside the polymer. Such a network can be formed by integrating nanotubes into a polymer matrix through covalent binding of nanotubes or by physical entanglement of nanotubes with each other. In thermoplastic crystallizing polymers, the upper boundary of CNT efficiency can also be reached by increasing the degree of polymer crystallinity due to participation of carbon nanotubes and improvement of the microstructure of the polymer including the orientational elongation of the nanocomposite. Nanocomposites of polymers with CNTs are promising for practical application if the nanotube efficiency is close to or exceeds the upper limit.