DETERMINATION OF BANDSHIFTS AS A FUNCTION OF STRAIN IN CARBON-FIBERS USING RAMAN-MICROLINE-FOCUS-SPECTROMETRY (MIFS)

Raman Microline Focus Spectrometry has been shown to have major advant ages over conventional point focus Raman microscopy for the study of s tress-induced shifts in carbon fibres. Averaged, representative spectr a have been collected from a sample length of 140 mu m, reducing possi ble errors in band positions incurred from localised stress and surfac e variations. In addition, it has been shown that data can be collecte d quickly at low laser powers, which avoid the localised heating effec ts experienced with point focus illumination. Unsized, pitch-based, ca rbon fibres, 6 mu m in diameter, were studied during a strain-release cycle. Within the scatter of the data, the E(2g) band returns to the o riginal position when the tension is released. However, the A(1g) band remains downshifted by ca. -5.6 cm(-1) upon release.