Fused fibrous arrays and mechanics of carbon nanotube sheets.

Abstract

Carbon nanotube sheets or Bucky Paper are macroscopic sheets comprised of random arrays of entangled carbon nanotube ropes. They are believed to be the most direct route to harnessing the exceptional mechanical properties of individual nanotubes at the macroscale since they are comprised almost entirely of the nanotubes themselves and are free of a supporting matrix. However the mechanical properties of conventionally manufactured Bucky Paper are disappointing, with a Young's Modulus of 1--4 GPa which is 2--3 orders of magnitude below that of an individual nanotube. Improved manufacturing techniques have resulted in only moderate improvements in mechanical properties. In the absence of a realistic measure of achievable moduli it is difficult to gage the success of these methods, and to determine whether the pursuit of further improvement is justified or feasible. This research establishes upper bounds on the effective modulus of carbon nanotube sheets using 2D network analyses and compares these with experimental results. The effects and relative importance of key parameters of nanorope waviness, inter- and intra-rope connections are also investigated and possible routes to improving the properties of these networked materials are identified.