Recent developments in the application of Raman spectroscopy to carbon-nanotube-based composite materials are reviewed. This technique may be used to identify carbon nanotubes, access their dispersion in polymers, evaluate nanotube/matrix interactions and detect polymer phase transitions. The Raman spectra of nanotubes can also be used to quantify the strain or stress transferred to nanotubes from the surrounding environment and to investigate local stresses and strains in polymers and composites. A polarized Raman technique was developed to detect the stress or strain in a matrix using randomly dispersed single-walled nanotubes. This technique has been used to detect and map stress fields in model fibre-polymer composites. The stress distributions around fibre breaks were mapped and compared with classical load transfer models.

The activity of a ZrO 2 -supported nickel catalyst promoted by silica (Ni-Si/ZrO 2 ) in CO 2 dry reforming of methane was carried out at 400 and 450 °C. The catalysts were prepared by an impregnation method and characterized by H 2 -TPR, XRD, TEM, TG-MS, Raman, XPS, and in situ XPS and DRIFTS. It was discovered that Ni-Si/ ZrO 2 showed higher initial conversion of CH 4 (0.50 s −1 ) and CO 2 (0.44 s −1 ), and stability for low temperature (400 °C) DRM reaction in comparison to an SiO 2 -supported nickel catalyst promoted by zirconia (Ni-Zr/SiO 2 ) (0.32 s −1 for both CO 2 and CH 4 ). The Ni-Si/ZrO 2 catalyst featured the formation of active nickel particles with a small size of 6−9 nm and with slightly strong electronic donor ability, stabilization of the initial metal nickel state under the reaction conditions, and the formation of easily removed C 1 coke. However, for the 450 °C DRM reaction, the coke that formed on the Ni-Si/ZrO 2 catalyst was mainly C 2 coke that was difficult to remove, because the CO 2 preferred to combine with H species rather than react with the coke. For the Ni-Zr/SiO 2 catalyst, the Ni 0 species was oxidized to a NiO species under the reaction conditions at 400 °C and could not be restored, leading to its deactivation.

The components that contribute to Raman spectral shifts of single-wall carbon nanotubes ͑SWNT's͒ embedded in polymer systems have been identified. The temperature dependence of the Raman shift can be separated into the temperature dependence of the nanotubes, the cohesive energy density of the polymer, and the buildup of thermal strain. Discounting all components apart from the thermal strain from the Raman shift-temperature data, it is shown that the mechanical response of single-wall carbon nanotubes in tension and compression are identical. The stress-strain response of SWNT's can explain recent experimental data for carbon nanotube-composite systems.

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Raman spectroscopy was used to map the stress distribution in the vicinity of discontinuities in a polymer using single-wall nanotubes seeded in the specimen. In the case of a hole in a polymer matrix subjected to unidirectional stress, the experimental stress field compared well with the classical linear elasticity solution. For a single glass fiber embedded in a polymer, the tangential thermal residual stress in the vicinity of the fiber was picked up by Raman spectroscopy and is in satisfactory agreement with a standard two-phase concentric cylinder model.