The existing methods for the determination of the orientational distribution functionf(β) in the nematic liquid crystals using X-rays have been reviewed. A simple Fourier method which givesf(β) in terms of the measured intensity is analysed. Using this distribution function, the accuracy with which the order parameters could be evaluated is discussed and the results show the elegance of the Fourier method used here.

Small angle X-ray scattering data have been recorded for the blends of styrene butadiene, styrene copolymer/polyaniline using the beamline of the LNLS (Laboratorio Nacional de Luz sincroton-Campinas, Brazil). Employing one-dimensional Hosemann's paracrystalline model, we have simulated the meridional reflections of these blends in order to compute the long periodicity and hence to find the variation with concentrations of the blends. Within the region of available experimental data we observe that there is a linear relationship between long periodicity and concentration of blends. These parameters are compared with physical measurements like tensile strength to find the structure–property relation in these blends.

We have analysed the broadening of X-ray reflections observed in non-mulberry silk fibres in terms of stacking faults and microstructural parameters using a single-order method and have, with these parameters, developed, for the first time, a procedure to compute the whole pattern of these silk fibres. The essential deviations in the values of microstructural parameters obtained from line profile and whole pattern fitting procedures are discussed in this paper.