Raman spectroscopic study of the effect of strain on the radial breathing modes of carbon nanotubes in epoxy/SWNT composites

In this report, the radial breathing modes (RBMs) intensities of single-walled carbon nanotubes (SWNTs) have been investigated by Raman spectroscopy. Epoxy composite samples with 0.025 wt% SWNT were subjected to deformation using four-point bending tests over a range of strain between –0.6% and 0.6%. Despite the low concentration of nanotubes, a strong Raman signal was observed with a near-infrared laser (wavelength of 785 nm). The RBM intensity values were found to depend on strain and also on the nanotube structure. Large intensity variations of between 30% and 100% were observed depending on the nanotube structure. The origin of this phenomenon has been discussed.