Analysis of the cure reaction of carbon nanotubes/epoxy resin composites through thermal analysis and Raman spectroscopy

The effect of the incorporation of single-walled carbon nanotubes (SWNTs) onto a diglycidyl ether of bisphenol A-based (DGEBA) epoxy resin cure reaction was investigated by thermal analysis and Raman spectroscopy. The results of the investigation show that SWNTs act as a strong catalyst. A shift of the exothermic reaction peak to lower temperatures is, in fact, observed in the presence of SWNTs. Moreover, these effects are already noticeable at the lowest SWNT content investigated (5%) with slight further effects at higher concentrations, suggesting a saturation of the catalyzing action at the higher concentrations studied. The curves obtained under isothermal conditions confirm the results obtained in nonisothermal tests showing that the cure reaction takes less time with respect to the neat epoxy. The thermal degradation of cured DGEBA and DGEBA/SWNT composites was examined by thermogravimetry, showing a faster thermal degradation for DGEBA-SWNT composites. Raman spectroscopy was successfully applied to demonstrate that the observed changes in the cure reaction of the composites lead to a different residual strain on the SWNT bundles following a different intercalation of the epoxy matrix. (C) 2003 Wiley Periodicals, Inc.