The development of pvdf/pei blended membrane: Effect of stirring time on membrane characteristics and performance

Abstract

The increased characteristics and performance of polyvinylidene fluoride (PVDF) membrane were investigated using polyetherimide (PEI) as a high-performance co-polymer for increased porosity, mechanical strength, PWF and thermal also chemical stability. The blend solution was prepared using a composition 2%PVDF/12%PEI/84%NMP/2%PEG-6000 (wt.%) with varying stirring time (7h, 12h, 16h, and 20h). The formation of a solid PVDF/PEI membrane was obtained using a non-solvent induced phase inversion (NIPS) method. Analysis of physical (surface and cross-section morphology, porosity, pore size) and mechanical (Young's modulus) characteristics, performance (PWF), thermal and chemical stability of the blended membranes were performed to evaluate the significance of stirring time effect. The resulting infrared spectra have confirmed the formation of PVDF/PEI blended membrane. All PVDF/PEI blended membranes were found to have symmetric structures with porosity 6.17%-30.64% and pore size 0.204 nm – 0.366 nm. The increase in mechanical strength can be seen from changes in Young's modulus values as the stirring time increases up to 12 hours. However, the stirring time for 16 and 20 hours resulted in a cast solution with too high viscosity resulting in a defect in the casting film using the automatic-casting knife. Increasing the homogeneity of PVDF/PEI cast solution as increasing stirring time has led to PEI characteristic properties that are capable of producing high PWF. This PVDF/PEI mixing method is a potential solution to obtain higher PVDF thermal stability and PEI chemical resistance.