A Study of Structure–Property Correlation on Wet Spinning Conditions in Heat-Resistant Poly(m-phenylene isophthalamide) Hollow Fiber Membranes

This study reports the influences of wet spinning conditions, such as the composition of external coagulant, the temperature of PMIA dope solution, and the air-gap distance between the spinnerets and the external coagulation bath, on the morphological features, mechanical properties, and membrane performance of heat-resistant poly(m-phenylene isophthalamide) (PMIA) hollow fiber membranes during a dry-jet wet spinning method. Scanning electron microscopy (SEM) analysis on the cross-section of the PMIA hollow fiber membranes clearly shows various effects of the wet spinning conditions on morphological features of the PMIA membranes. In addition, it is observed that the tensile strength of the PMIA membranes decreased with increasing DMAc content in the external coagulant and temperature of the dope solution, and the tensile strength decreased with decreasing air-gap distance. Furthermore, the water permeability and rejection analysis present consistent trade-off trends across all the wet spinning conditions. Interestingly, significantly high correlations are observed between the pore structure, mechanical properties and membrane performances of PMIA hollow fiber membranes, as well. As a result, based on the findings obtained from this study, we have gained confidence that the structure and properties of the final PMIA membranes can be appropriately controlled through the control of the dry-jet wet spinning process in the manufacturing of PMIA hollow fiber membranes.