DMSO Intercalation in Selected Kaolinites: Influence of the Crystallinity

The present study deals with the relation between crystalline order in kaolinites and their ability to intercalate DMSO. Raw clays and kaolinite–DMSO complexes are analyzed using FTIR, XRD powder diffraction and differential scanning calorimetry and thermogravimetric analysis (DSC-TGA). The crystallinity is accessed using the Hinckley index (HI) from the raw clays’ XRD patterns and the p2 factor from their FTIR spectra. The intercalation ratio is evaluated from XRD and compared among the samples. The thermal analyses show a decrease in the dehydroxylation temperature in the DMSO–kaolinite complexes, indicating a decrease in the interlayer cohesion that may be useful to improve the delamination of kaolinite. The analysis of the coherent scattering domain size in the raw and the DMSO-intercalated samples indicates that the ordering is not affected during the DMSO intercalation. From these results, it is deduced that DMSO intercalation is favored by an increased crystallinity, as revealed by the intercalation ratio from XRD and the DSMO release during DSC-TGA analysis.

X-Ray Diffraction Application for the Study of the Fine Structure of Carbon Fibers

The fine structure of carbon fibers, obtained according to specific preparation techniques, has been studied. It has been shown that the fiber material is heterogeneous, its component composition is determined by thermomechanical treatment conditions and addition of boron; also it depends on the angle φ of coherent scattering domain orientation relative to the thread axis. The mean coherent scattering domain sizes increase in transition to the components corresponding to smaller d002 values. Increase in temperature and duration of heat treatment, as well as the presence of a boron-containing additive, ensures formation of the components corresponding to smaller interplanar spacing d002 values in the carbon material. The observed influence of temperature and duration of heat treatment, as well as the angle of coherent scattering domain orientation relative to the thread axis, upon the component composition makes it possible to assume that the process of carbon fiber material transformation into a state of greater stability presumably develops through a number of metastable stages.