3.7. Fourier-transfonn infrared spectroscopy (FTIR)
FTIR analysis aided identification of the functional groups pre¬sent in the samples and revealed how the composition and struc¬ture of the banana fibers changed along the treatments. Fig. 6 contains the FTIR spectrum of the banana peel bran and CNFs. The large absorption band in the region of 3650—3000 crrr1 referred to —OH groups and represented the hydrophilicity of the natural fibers (bran) and CT- and ET-treated CNFs. The peak at 3337 crrr1 corresponded to —OH stretching; this band was related to specific intramolecular hydrogen bonds of cellulose II (Yang, Yan, Chen, Lee, & Zheng, 2007; Zuluaga et al., 2009). The bran displayed a small band in the region of 2920 crrr1, typical of the stretching vibrations of the C—H bonds in hemicelluloses and cellulose. This peak became more intense in the spectra of the treated CNFs samples.