Investigation into the deformation of carbon nanotubes and their composites through the use of Raman spectroscopy

The deformation micromechanics of single-walled carbon nanotube (SWNT) and multi-walled carbon nanotube (MWNT) particulate nanocomposites has been studied using Raman spectroscopy. SWNTs prepared by two different methods (pulsed-laser and are-discharge) and MWNTs have been used as reinforcement for a polymer matrix nanocomposite. The carbon nanotubes exhibit well-defined Raman peaks and Raman spectroscopy has been used to follow their deformation. SWNTs have been deformed with hydrostatic pressure in a diamond anvil pressure cell and has been found that the G' peak position shifts to a higher wavenumber with hydrostatic compression. It has been found that for all nanocomposites samples deformed, the G' Raman band shifts to a lower wavenumber upon application of a tensile stress indicating stress transfer from the matrix to the nanotubes and hence reinforcement by the nanotubes. The behaviour has been compared with that of high-modulus carbon fibres and has been modelled using orientation factors suggested initially by Cox. In this way it has been possible to demonstrate that the effective modulus of SWNTs dispersed in a composite could be over 1 TPa and that of the MWNTs about 0.3 TPa. (C) 2001 Elsevier Science Ltd. All rights reserved.