Unusual ignition behavior of polyurethane/carbon nanotube composites with a He-Ne laser excitation (632.8 nm) during micro-Raman spectroscopy

We report a spontaneous ignition of carbon nanotubes/polyurethane composite under He-Ne laser. The ignition of the composite is caused by rapid increase of the temperature to at least 660 K due to absorption of light by carbon nanotubes. This temperature was estimated from G band downshift of the carbon nanotube caused due to the bond loosening due to thermal expansion of the bonds. The morphology of the nanocomposite under ignition was studied using SEM and optical microscopy, and revealed craters of dimension on the order of the focused laser beam. This unusual synergistic effect was hypothesized as the result of poor thermal conduction between carbon nanotube and polymer matrix. (C) 2006 Elsevier Ltd. All rights reserved.