Manufacturing and Applications of Carbon Nanotube Sheet RACHIT MALIK 1 , NOE ALVAREZ 1 , MARK HAASE 1 , BRAD RUFF 2 , YI SONG 2 , BOLAJI SUBERU 2 , DUKE SHEREEN 3 , DAVID MAST 3 , ANDREW GILPIN 4 , MARK SCHULZ 2 , VESSELIN SHANOV 1 1,4 School of Energy, Environment, Biological and Medical Engineering, 2 School of Dynamic Systems, 3 Department of Physics, Nanoworld Laboratories, University of Cincinnati, Cincinnati, OH 45221 USA. http://www.min.uc.edu/nanoworldsmart Abstract: - Individual Carbon nanotubes (CNTs) are known to have exceptional mechanical and electrical properties. The transfer of these extraordinary qualities into CNT products, without compromising on performance, remains a challenge. This paper presents an insight in the manufacturing of CNT sheets, the use of plasma for functionalization of nanotubes and their applications. Sheets of multi-walled carbon nanotubes (MWNTs) drawn from spin-able CNT arrays have been developed. The sheets comprise nanotubes aligned in the pulling direction as shown via Scanning electron Microscope (SEM) characterization. The alignment of the nanotubes imparts anisotropic properties to the sheet and leads to a significantly higher Electromagnetic Interference (EMI) shielding effectiveness. Surface modification of aligned MWNT sheets was carried out via an atmospheric pressure plasma jet during the post-treatment process. Helium/Oxygen plasma was utilized to produce carboxyl (-COO - ) functionality on the surface of the nanotubes. X-Ray Photoelectron Spectroscopy (XPS) confirms the presence of functional groups on the nanotube surface. The sheet was further characterized using Raman Spectroscopy, Fourier Transform Infrared (FTIR) Spectroscopy and Contact Angle testing. Composite laminates made from functionalized CNT sheets in a polyvinyl alcohol (PVA) matrix demonstrate more than 100% increase in tensile strength over those made with pristine sheets used as reinforcement material. Key-Words: - Carbon nanotube, sheet, plasma, XPS, EMI shielding, composites. 1. Introduction Carbon Nanotubes (CNTs) have come a long way since their discovery in 1991 1 . The arc discharge evaporation method initially used to synthesize nanotubes has given way to large scale production by chemical vapor deposition 2 . The individual nanoscale tubules of carbon have exceptional mechanical strength, high Young’s modulus, 3 and superior specific conductivities 4 . During growth, depending on the conditions in which they are formed, nanotubes assemble either as double- walled/multi-walled co-axial tubules (DWNTs/MWNTs) or as bundles (ropes) consisting of individual tubes (single-walled nanotubes, SWNTs) packed in two-dimensional triangular lattices 5 . Carbon nanotubes have been extensively employed in many applications ranging from electrodes for fuel cells 6 , batteries 7 , super- capacitors 8 , solar cells 9 , as substrates for biological cell growth 10, 11 and materials for EMI shielding 12 . Transparent and conducting thin films for touch screens 13, 14 , polarized light emitters 15 , loud speakers 16 , and high performance energy storage devices 17 have been demonstrated. Individual CNTs have demonstrated exceptional mechanical strength and superior electrical conductivities, but extrapolating these properties to macroscopic structures of carbon nanotubes has been a challenge. The CNT dispersion approach is widely used in solution processing, melt processing, electro- spinning, and coagulation spinning of Polymer/CNT composites 18, 19 . CNTs typically have to be purified by washing in acids before they can be deposited as paper-like films or in threads. The nanotubes thus produced typically demonstrate poor mechanical properties and are randomly oriented. The dispersion of long CNTs is hindered by their Recent Advances in Circuits, Communications and Signal Processing ISBN: 978-1-61804-164-7 327