THE ANALYSIS OF SLIGHTLY DISTORTED SAXS LAYER LINE PATTERNS FROM FIBRILLAR 2-PHASE SYSTEMS WITH SHORT-RANGE ORDER

The information content of small-angle x-ray scattering from fibrillar two-phase systems under strain is discussed. The experimental background is a study of SBS star block copolymer samples during elongation using synchrotron radiation and a two-dimensional detector. The samples exhibit a layer line pattern with the slight indication of a four-point diagram. The theoretical considerations are verified using the experimental data. Special scattering curves (sections and projections) can be extracted from the scattering pattern and are used to describe mathematical peculiarities of the pattern and their physical background. The scope of the paper covers product separability in cylindrical coordinates and an analysis of the separated factors. From the physical point of view information is gained on the validity of the approximation by a "one-dimensional fibrillar system" and the order within bundles of fibrils. An expression is given for the background scattering caused by an ensemble of non-identical oblong particles, organized in bundles of oriented fibrils. The difference in the information on the structure, obtainable from either section or projection, is discussed.