The effect of dialysis environment and reprocessing procedure on the mechanical and structural stability of high flux polysulfone membrane

Abstract

Although there are many clinical researches inthe open literature, biocompatibility and performance of reprocessed hemodialysis membranes are not still well defined. This thesis aims to fulfill yhe deficiency in the experimental studies performed from an engineering point of view. In line with this aim, Fresenius FX80 polysulfone hemodialyzer membrane was exposed to formaldehyde and bleach after a dialsis session. The mechanical stabilities of virgin and user-processed fibers were investigated by tensile tests consisting of monotonic and cyclic loading. The surface features and morphology changes were examined by SEM and AFM. The crystallinity of the mechanically tested virgin and used-processed fibers was determined by XRD. The experiments showed that the ductility,toughness and strength of the used-processed fibers decrease. The microscopic studies depicted some morphological changes such as increase in pore size and deformation in pore shapes. The X-ray diffraction method demonstrated the increase in the crystallinity of monotonically loaded used-processed or virgin fibers. However, it is seen that the cyclically loaded fibers undergo some structural changes, although the crystalline portion in their structure does not increase. This result can be related with the loading cycles in the elastic region and further studies are needed to determine the behavior of polymeric material. In conclusion, reprocessing and dialysis structurally changes the hemodialyzer membrane, which may result in some complications during hemodialysis reuse.|Keywords: High Flux Polysulfone Hemodialyzer, Reuse, Formaldehyde, Bleach, Reprocessing, SEM, AFM, XRD, Tensile test.