Thermal, X-Ray Structural and Microscopic Studies of the Effect of Transmembrane Pressure on the Crystallographic and Surface Parameters of OFAM-K and OPMN-P Nanofiltration Membranes

Experimental studies and analysis of the effect of transmembrane pressure on the composite porous film material of OFAM-K, OPMN-P membranes and their components by differential scanning calorimetry (DSC), X-ray diffraction analysis and optical microscopy are presented. Investigations of nanofiltration composite materials by differential scanning calorimetry make it possible to study thermal effects that cause changes in the structure and phase transformations with increasing temperature in the membrane sample. X-ray diffraction analysis of the crystalline and amorphous regions of composite films using the radial distribution function allow the change in the unit cells in the membrane polymer sample due to an increase in the interatomic distances to be established. The crystallinity in a membrane sample exposed to transmembrane pressure increases from 44 to 55% due to the appearance of an additional crystalline phase in the film. Optical microscopy studies of the membrane substrate show a morphological feature that resembles fiber compaction, as well as the presence of microscopic voids, which can ultimately be explained by the presence of more knitted fibers in some areas of the membrane.