This slide shows FTIR spectra of the treated and untreated fibers.
The peak at 3200-3600 cm-1 involves OH stretching and the peak at 1030 cm-1 involves CH3 stretching.
It is seen that the intensity of both peaks is higher for untreated sample, compared to that of the treated one.
This arises from that, not only the cellulose, but also multi-components are in the untreated samples.
Therefore, the FTIR change is additionally responded from these covering materials, resulting in the increase in the intensity of OH and CH3 stretching.