Structure Regulation And Characterization Of PVDF Membranes By NIPS

In this paper, Poly(vinlidene fluoride) membranes were prepared via nonsolvent induces phase separation (NIPS) method, the effect of influence factors on the performance of PVDF membranes was investigated.Firstly, poly(vinylidene fluoride) membranes were prepared with various residence times using water-ethanol (50:50,mass ratio) and pure ethanol coagulants as first coagulant, respectively. The results showed that the longer residence time in the first coagulant contributed to improvement of the filtration properties. Contact angles of the top-surfaces and bottom-surfaces of membranes decreased as residence time increasing in the first coagulant, and the top-surface showed better hydrophilicity than that of the bottom-surface. Additionally, the short-time delay demixing process in water-ethanol first coagulant resulted in a thin dense layer near the top surface, the layer become more thinner as the residence time increasing. It explained decrease in mechanical properties of the corresponding PVDF membranes. The longer time delay demixing process in that of ethanol contributed to the shift of the inter-globules to the cellular morphology, which was beneficial for mechanical properties improvement.Secondly, PTMGDA was obtained by the reaction of PTMG and Acryloyl Chloride, and the optimal reaction temperature is35℃, the optimal reaction time is8h, the optimal ratio is1:2.5. A new monomer mixture is configured using PTMGDA instead of MMA, the effects of the addition of the monomer mixture to PVDF membrane were investigated. The results indicate that with the increasing of the monomer mixture content in casting solution, the mechanical property and the contact angle of the membrane decrease, while the flux has a novel result, when the amount of the monomer mixture is3g, the membrane has largest flux.Finally, the differences between hollow membranes prepared on the basis of the optimal casting solution in membrane performance were studied. Base on the result of experiment, the effect of new monomer mixture obtained by PTMGDA is better than MMA.