3D model of short-range order of one-hour milled cellulose

The main purpose of this work was to investigate the structure of short-range order of microcrystalline cellulose (MCC) milled for one hour. Usually mechanical milling produces amorphous segments of crystalline cellulose. Investigation of short-range order was conducted by Debay's method to get X-ray diffraction (XRD) pattern when the coordinates of atoms in a cluster are known. The samples were studied by XRD. Crystallinity degree was measured using Segal's method. Cellulose I alpha and I beta were used as the initial structures to form clusters. The profile factor (R-p) was used, as the evaluation factor. The results showed that the cluster based on cellulose I beta insufficiently characterized the short-range order of crystalline-amorphous cellulose (R-p>18%). Consequently, we examined a unit cell consisting of one cellobiose fragment. The final modeling cluster had the size of 35 angstrom x22 angstrom x29 angstrom. The cluster consisted of 3 layers orientated randomly in relation to one another. The result of comparison of theoretical and experimental XRD patterns revealed that R-p was 11.4%. Therefore, the structure of short-range order of one-hour ground cellulose can be characterized by disordered cellulose chains with the length of 21 angstrom.