A Raman spectroscopic investigation of heating effects and the deformation behaviour of epoxy/SWNT composites

Raman spectroscopy has been used to characterise the deformation behaviour of single-walled carbon nanotube (SWNT) reinforced epoxy resin composites and associated heating effects. It has been found that the Raman G′ band of the SWNTs shifts to lower wavenumber as the intensity of the incident laser beam is increased for both the as-received SWNTs and the SWNT/epoxy composite, due to laser beam heating effects. The G′ band of epoxy/SWNT composites containing 0.1% of SWNTs was also found to shift, during deformation under four-point bending, to higher wavenumber in compression and to lower wavenumber in tension. At high strains (>±0.5%) the shifts reach plateau levels in both tension and compression due possibly to interfacial failure and nanotube buckling (in compression). It was also shown that the deformation behaviour of the SWNTs in composites varies with the resin curing temperature due probably to the presence of residual stresses.