Effects of PVDF Crystallization on Polymer Gelation Behavior and Membrane Structure from PVDF/TEP System via Modified TIPS Process

Abstract

Poly (vinylidene fluoride) (PVDF) hollow fiber membranes are prepared by modified TIPS from PVDF/triethyl phosphate (TEP) system. It is revealed by differential scanning calorimetry (DSC) that PVDF crystallization capacity increase with polymer content increasing. Additionally, crystallization behavior and crystal structure of PVDF in PVDF/TEP systems are investigated by scanning electron microscopy (SEM) and wide angle X-ray diffraction (WAXD). PVDF concentration has a remarkable effect on PVDF crystallization behavior. Dendritic pore structures are obvious when PVDF weight ratio is 30% in polymer/diluent solution. However, discernable spherulitic structures are obtained when PVDF weight ratio reaches to 35%.