Small-Angle X-Ray Scattering in Various Cellulose Fibers and Its Relation to the Micellar structure

Abstract

The study of the molecular structure of cellulose fibers by x-rays has been concerned until very recently with diffraction of only relatively wide angles. Almost no work has been done on the diffraction and scattering of x-rays within very small angles adjacent to the primary beam. The only fact known was that such "small-angle scattering" is produced by ramie and viscose rayon. In the present study, the small-angle scattering by various cellulose fibers has been investi gated and it has been found that the scattering by different fibers is completely different. The hypothesis that the small-angle scattering in cellulose fibers would be related to the micellar size and distance is substantiated by the fact that an experimental change of those distances results in a corresponding (inverse) change in the extent of the scattering. On this basis the difference in the scattering patterns of different fibers is explained as a difference in the size and distance of the cellulose micelles or crystallites. An orientation of crystallites is also expressed in the small-angle diffraction pattern giving rise to the interesting phenomenon of "cross" formation when the crystallites form an angle with the long axis of the fiber. The angle between the intersecting lines of the cross proved to be related to the pitch of the spiral of the crystallites in the fiber.