Assessment of Segal method for identifying crystallinity evolution in developing cotton fibers

The crystallinity index (CI) is an important parameter in evaluating cotton fiber quality. Due to its ease and speed in measuring CIs from X-ray diffraction (XRD) patterns, the Segal method is popularly used. In this study, we assessed the Segal method for monitoring the crystallinity evolution in developing cotton (Gossypium L.) fibers between 20 and 60 days post anthesis (DPAs) by comparing Segal CIs with those obtained from a Fourier transform infrared spectroscopy-based method and other XRD-based methods. The Segal method estimated higher CIs than other methods, especially for shorter DPAs. The Segal method suggested a rapid evolution of crystallinity in the early developmental stage, whereas other methods suggested a gradual increase in crystallinity. The calculation of diffraction patterns for cellulose Iβ crystallites with different sizes showed very little effect of the crystallite size on the Segal CIs for developing cotton fibers studied.