Effects of post-treatment on the structure and properties of PVDF/FEP blend hollow fiber membranes

Abstract

Polyvinylidene fluoride (PVDF)/poly(tetrafluoroethylene-co-hexafluo-ropropylene) (FEP) blend hollow fiber membranes were prepared by the melt-spinning method. The effects of drawing conditions (drawing ratio and temperature) on the structure and properties of the membranes were investigated by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and analysis of membrane morphology. The storage modulus increased with increasing drawing temperature at the same drawing ratio, which improved the membrane's elasticity. The quantity and pore size of the interfacial microvoids both increased significantly with an increase in the drawing ratio at the same drawing temperature. Finally, the membranes were evaluated for their performance in vacuum membrane distillation (VMD). All the membranes had a salt rejection higher than 99.0%.