X-ray study of the orientational order of a concentrated dispersion of kaolinite under flow

Diffraction with high-energy X-rays is used to determine the orientational alignment of kaolinite particles dispersed in water as they flow down a pipe. Angle-dispersive and energy-dispersive diffraction methods are compared. Detailed studies of samples as thick as 1 cm were possible using energy-dispersive diffraction. A tomographic technique with the sample scanned and rotated in the beam allows maps of the alignment to be determined. The alignment across a pipe of rectangular section was determined. A strong effect caused by the walls was observed, the plate-like particles tending to lie parallel to the wall near the boundary of the pipe.