Raman spectroscopic studies of nomex and kevlar fibres under stress

The vibrational Raman spectra of single fibres of Nomex and Kevlar have been studied and vibrational assignments made. Commercial samples of Kevlar 29 and Kevlar 49 were found to be identical spectroscopically. Distinguishing features in the Raman spectra of Kevlar and of Nomex were identified for the purpose of spectroscopic or microprobe characterisation of these materials as single fibres or as small particles (∼ 2 μm). The Raman spectra of Kevlar and Nomex fibres which had been subjected to mechanical stresses of up to 4.5 kg mm−2 were also analysed and comparisons made with previous results on stressing experiments in the literature for Kevlar.