Raman spectroscopy used for estimating the effective elastic modulus of carbon nanotubes in aligned multi-walled carbon nanotubes/ epoxy composites under tensile loading

This study used polarized Raman spectroscopy to evaluate strain in multi-walled carbon nanotubes (MWCNTs) in aligned MWCNT/ epoxy composites to clarify the effective elastic modulus of MWCNTs in the composites. The Raman shift rate of the G’ band of the MWCNT corresponding to the tensile strain (%) of the composite specimen was −18.84 cm−1/%. Reported values of the Raman shift rate for pitch-based carbon fibers indicated the effective Young’s modulus of the MWCNT as approximately 377 GPa. Using Mori–Tanaka theory and considering the three-dimensional orientation distribution of MWCNT, the effective Young’s modulus of the MWCNT was estimated as 400 GPa. The results demonstrated Raman spectroscopy as useful for experimental evaluation of the effective Young’s modulus of MWCNT in the composite.