Vibrational spectroscopy investigation of Australian cotton cellulose fibres.Part 2. A Fourier transform near-infrared preliminary study†
Raw naturally coloured and white cotton cellulose fibres were investigated by Fourier transform near-infrared (FT-NIR) spectroscopy and chemometric methods, namely principal component analysis (PCA). In general, the white cotton exhibited bands that could be associated with the structural features of the cotton cellulose polymer. But the FT-NIR spectrum of the green cotton, which is reported for the first time, exhibited a sharp band at 4250 cm–1. Further band analysis indicated that green cotton contains a higher C–H content and a lower C–C/C–O and O–H fractions than other natural cotton fibres, suggesting that it has undergone an oxidation process as indicated in the previous FT-Raman spectroscopic study (see Liu, Y., Kokot, S., and Sambi, J., Analyst, 1998, 123, 633). Although the PCA scores plot of FT-NIR spectra of seven types of cotton fibres showed no better separation than that of FT-Raman spectra, it is still possible to differentiate the various types of natural cotton fibres.