Single-walled carbon nanotubes (SWNTs) have exceptional mechanical and functional properties. Many researchers consider SWNTs as the most promising reinforcement for realizing the optimal structural and multifunctional potential of the next generation of high performance nanocomposites. However, due to poor dispersion, weak interfacial bonding and deficient tube orientation, current nanotube-based nanocomposites fail to realize their anticipated properties. A new approach was developed by the authors to use preformed nanotube tube networks (called buckypapers) and a resin infiltration method for producing bulk polymeric nanocomposites with controlled nanostructure and high tube loading. Desired tube alignment in nanocomposites can be achieved by using magnetically aligned carbon nanotube buckypapers, in which SWNTs will tend to align along the direction of applied magnetic field. The mechanical properties of the resultant nanocomposites have been tested. The storage modulus of the magnetically aligned nanocomposites is as high as 47 GPa, which is one of the highest reported values of nanotube-reinforced composites.
In this research, we investigated the influences of tube dispersion, loading and orientation on the mechanical properties of SWNT-reinforced composites. Random and aligned discontinuous reinforcement models of composites were applied to predict the tensile moduli of both individually dispersed SWNT-based and SWNT rope-based nanocomposites. The nanostructural parameters used in the calculation models were determined based on our experimental observations. Comparisons between theoretical estimates and experimental results have shown that the formation of SWNT ropes in the composites has a significant influence on the mechanical properties. The experimental results of the both random and aligned SWNT rope composites are in good agreement with the theoretical predictions.