STUDY ON THE CRYSTALLINTY OF REGENERATED CELLULOSE FIBRES USING THE X-RAY DIFRACTOMETER

Relative values of the crystallinity of the regenerated cellulose fibres produced by various methods were determined.The hydrolized cotton, which had been mercerized previously, was used as a crystalline standard, and the saponified cellulose acetate in ethyl alcohol as an amorphous standard. It was found that there is an appreciable variation in the crystallinity of regenerated cellulose fibres, depending upon the method of production. Polynosic fibres and cuprammonium rayon are generally highly crystalline, while tire cord rayon generally has a low crystallinity. The amorphous contents of these fibers are approximately proportional to their accessibility determined from their moisture regain. However, a strictly linear relationship between the two values is not observed, since the accessibillity also depends upon the size of the crystalline region. This phenomenon is confirmed by comparing the half-widths of the crystalline peaks.The effect of various treatments on the crystallinity of regenerated cellulose fibers was also studied. It was shown that changes in the crystallinity depend upon the type of fine structures in the original fibers, and that the fine structure in the polynosic fibers is least affected by after treatments, especially with aqueous alkali.