X-ray small angle scattering of ramie and rayons

The small angle scattering of ramie and of 25 highly oriented rayon samples with widely different prehistory was examd. in both the air-dry and water-swollen condition with monochromatic radiation. For some rayons the curves show distinct max. or inflection points in either the swollen or dry state indicating a max. of relatively low intensity superimposed on a normally descending small angle intensity curve. The Bragg spacing corresponding to the max. are close to 80 A. for the swollen fibers and to 50 A. for the dry fibers. Other specimens show only faint indications of superimposed max. or none at all. The existence of max. indicates a micellar structure of unexpectedly high regularity in part of the fiber substance with interparticle distances being given by the Bragg spacings. The Guinier method for dil. systems (C.A. 47, 8507f) when applied to the intensity curves for swollen samples not showing a max. gives values between 35 and 55 A. for the diam. of the parallel cylinders assumed. A preferred spacing of the same order of magnitude, about 40 A. for the dry and 60 A. for the swollen fibers, is obtained by evaluation of the intensity curves by using Kratky's approximation (Janeschitz-Kriegl, et al., C.A. 46, 6377c). No clear correlation between small angle scattering features and other known properties of the rayons was found.