Effect of pressing on the infrared spectra of single cotton fibers

Fourier transform infrared spectra of single fibers of cotton and 18% NaOH treated cotton were obtained before and after fiber pressing to investigate the effect of pressing on the sample. Pressing resulted in improved spectral quality in some regions (e.g., OH stretching) and deteriorated spectral quality in other regions (e.g., CH stretching). Second derivatives of these IR spectra reveal alterations in vibration modes. Thin immature cotton was included in this study to provide a comparison to fibers thinned by pressing. Infrared crystallinity indices, i.e., the ratio of A(1370)/A(2900) differ between the pressed and impressed cotton fibers. Because both quantitative and qualitative changes can result from compression of cotton fibers, caution is required in both selection of the sample preparation method and in interpretation of the infrared spectra.