Multifunctional Nanoprepregs Based on Aligned Carbon Nanotube Sheets

The unique properties of carbon nanotubes (CNTs), such as high strength and stiffness, extremely large specific surface area, low density and high electrical and thermal conductivities, open up opportunities for a wide range of applications. This has led to widespread research on the synthesis of multiscale CNT-based polymeric composites transferring the properties from nanoscale to macroscale. Currently known conventional methods for producing CNT composites rely on dispersing short nanotubes in polymer matrices or infiltrating CNT "buckypaper" with resins. Unlike conventional methods, in this work, super-aligned long CNTs were directly drawn from the vertically aligned CNT arrays and assembled into high volume fraction (∼60 vol%) composites. These critical structural features allowed the CNT composites to reach tensile strengths over 1.8 GPa and electrical conductivity ∼700-800 S/cm. Thermoplastic and thermosetting polymers were utilized for the fabrication and the results were compared. Our observation suggests that the strengthening and conducting mechanism is derived from the synergistic effect of high degree of CNT alignment, long CNT length, high volume fraction and uniform distribution of CNTs in the polymer matrix produced by spray-winding. © 2012 Materials Research Society.