Celluloses relative crystallinity

The evidence presented fails to suggest the causes for the large variations in crystallinity estimates which have been reported for similar cellulosic materials. There is a possibility that the different methods may not measure precisely the same characteristic of the material. It also may be that relative crystallinity is not a fixed quantity in any case but depends on circumstances involved in the measurement, such as the amount of swelling. The estimates reached by different methods need to be reconciled. At present, crystallinity estimates which depend wholly or in part on X-ray diffraction seem to be much higher than those obtained by chemical methods. The fact is that X-ray diffraction methods are ideal for studies of the crystalline fraction but are necessarily indirect in application to the non-crystalline fraction. The converse is true for the chemical approach. Apparently a combination of diffraction and chemical methods may adjust the existing differences. 

Relative crystallinity undoubtedly influences such properties of cellulosic materials as rigidity, flexibility, plasticity and extensibility. Likewise the amount and reactivity of intercrystalline cellulose are major factors in common processing treatments such as bleaching, dyeing, pulping and wet finishing. Further refinement of measuring methods and the development of further correlations between crystallinity and fiber properties would contribute much to this important field. 

At the molecular level, portions of cellulose assume a highly structured crystalline form, while other parts are amorphous. Amorphous cellulose is more easily digested by enzymes than the crystalline parts. The fraction of crystalline cellulose is called the relative crystallinity, an index of digestibility. The crystallinity of commercially available substrates lies between 85 and 90%. Even so-called non-crystalline cellulose has a relative crystallinity of 65%. 

Neubebg, Carl, Biochemical Reductions at the Expense of Sugars, 4, 75-117 Newth, F. H., The Formation of Furan Compounds from Hexoses, 6, 83-106 Newth, F. H. See also, Haynes, L. J. Nickerson, R. F., The Relative Crystallinity of Celluloses, 6, 103-126 Noed, F. F., [Obituary of] Carl Neuberg, 13, 1-7... 

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