Effect of PVP Additive on PVDF/TPU Blend Hollow Fibre Membranes by Phase Inversion

Asymmetric blend hollow fibre membranes were made from a new casting dope containing poly(vinylidene fluoride) (PVDF)/thermoplastic polyurethane (TPU)/ N,N-dimethylacetamide (DMAc)/polyvinylpyrrolidone (PVP). The separation property, microstructure, crystalline phase of membranes, and membrane strength were characterized by bovine serum albumin (BSA) retention experiments, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy- attenuated total reflection (FTIR-ATR), differential scanning calorimetry (DSC) and tensile testing, espectively. PVP at low concentration (≤3 wt%) was a significant demixing enhancer hich thermodynamically controlled the phase inversion process, improved flux, educed α-form crystal structure, and decreased crystallinity of PVDF in membranes. t high concentration of PVP (>3 wt %) due to viscosity buildup, kinetic hindrance verwhelmed the thermodynamic factor which suppressed the formation of acrovoids, reduction of flux, nd increase in crystallinity of PVDF in membranes.