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

Abstract

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 Iα and Iβ 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 Iβ 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 35Å×22Å×29Å. 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 Å.