XRD Analysis Applied to Natural Fibers

The XRD is a method used generally to evaluate the degree of crystallinity of several materials. The free hydroxyl groups present in the cellulose macromolecules are likely to be involved in a number of intramolecular and intermolecular hydrogen bonds, which may give rise to various ordered crystalline arrangements [7, 22]. Native cellulose is known to be a composite of two distinct crystalline modifications, namely and I, whose fractions depend on the origin of the cellulose sample [30, 59, 60]. The 

In addition, I cellulose is reported to be the dominant polymorph in bacterial and alga celluloses, while Ip cellulose is predominant in higher plants such as cotton and wood [30]. Therefore, the crystalline structure of cellulose affects the physical, thermal and mechanical properties of the natural fibers. The degree of crystallinity of cellulose is one of the most important crystalline structure parameters. The rigidity of cellulose fibers increases while the flexibility decreases by increasing the ratio of crystalline to amorphous regions [58]. 

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