X-Ray Analysis of Characteristic Features of the Heterogeneity of Cellulose Fibers When Interacting With Water

We have developed a procedure for quantitative analysis of small-angle x-ray scattering by cellulose fibers swollen in water, enabling a comparative estimate of the interfacial surface area between the crystalline and amorphous phases and also the specific surface area of the crystallites. We show that the specific interfacial surface area between the crystallites and the swollen amorphous phase of the polymer practically remains unchanged on going from cotton to less crystalline mercerized and viscose rayon fibers. Mercerization of cotton fibers, under conditions ensuring complete transition of cellulose I to cellulose II, leads to an increase in the specific surface area of the crystallites by a factor of 1.4, suggesting a decrease in crystallite sizes and an increase in the amount of crystalline phase per unit weight in the polymer. Breakdown of the morphological structure of the natural cellulose material when obtaining viscose rayon fibers leads to formation of a system of crystallite formations, the specific surface area of which is 1.82 times greater than the analogous parameters for cotton.