An X-ray method of crystallinity determination has been developed which takes into account the diffuse scattering due to thermal vibrations and lattice imperfections in the crystalline part of a substance. Application of the method to a series of polypropylene samples shows that this diffuse scattering is predominantly caused by thermal motions.The normalization of the scattering curve leads to special absorption corrections for Compton scattering and indicates a scattering effect attributed to the carbon-hydrogen bond orbital

SHORT COMMUNICATIONSancies. For example, the indices 732 and 534 had calculated relative intensities of 5.1 and 2.5 respectively but no trace of these lines were found on the film. Conversely the indices 521 and 536 had very low calculated relative intensities, 0.4 and 0.3 respectively and the observed relative intensities were 3.1 and 4.9. The major instances of discord are summarized in Table 2.There is no obvious indication of preferred orientation. This suggests that there may be some periodic faulting in the structure causing this phenomenon. The means of assessing the convergence of the van Cittert method of deconvolution is discussed with the help of the corresponding operation in Fourier space.

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combination of small-angle neutron scattering (SANS) and nitrogen sorption is used to elucidate the mechanism of nitrogen sorption in different meso-and microporous silicas with regular as well as disordered pore structures. The concept of the chord-length distribution represents a suitable approach to describe the subsequent stages of nitrogen sorption. A general approach is developed to relate the SANS patterns during condensation to the size distribution and statistical filling of regularly distributed mesopores. The technique represents an experimental method to verify theories for sorption in mesoporous media. -

Density transition of finite width between the phases and density fluctuations within the phases produce systematic deviations from Porod's law, which can be detected by suitable intensity plots. These plots permit the correction of the intensity and the determination of structural parameters related to the causes of the deviations.