X-Ray Diffraction Studies of Changes in Crystallinity and Amorphism of Microfiltration Membranes MFFK-G-025 and MMK-045

The paper presents the data on the X-ray diffraction analysis of air-dry, water-saturated and working samples of the MFFK-G-025 and MMK-045 membranes obtained during microfiltration separation of process solutions. A decrease in crystallinity of the membrane samples is noted during their water saturation and operation, which affects the microfiltration separation of process solutions. The reduced peak intensities of the bands are analyzed in the X-ray diffraction patterns. Five distinct reflections responsible for the crystallinity of the membrane and four amorphous halos are observed in the diffraction patterns of all MFFK-G-025 membrane samples, and two distinct reflections responsible for the crystallinity of the membrane and two amorphous halos are visible in the case of MMK-045 membrane samples. The crystallinity degree of the MFFK-G-025 membrane has been decreased from 58.16 to 36.83, and that of the MMK-045 membrane from 33.51 to 20.21. The decrease in the peak intensity in the diffraction patterns of working membrane samples compared to air-dry ones indicates a change in the structure of water in the membrane itself, molecular water becomes weakly bound “liquid water”. It can be assumed that the structural rearrangement of the macromolecules of the active layer of the MFFK-G-025 and MMK-045 membranes affects their conformation, i.e. a redistribution of the ratio of amorphous and crystalline segments of the membranes occurs.

crystallinity, amorphism, microfiltration membranes, chemical structure, interplanar distance, X-ray diffraction analysis