Preparation And Characterization Of PVDF And Its Hybrid Membrane

Poly(vinylidene fluoride) (PVDF) is a kind of membrane material with excellent characteristics. In this thesis, flat PVDF membranes were prepared by phase inversion method. The effect of preparation conditions on the structure and properties of PVDF membranes were studied. PVDF hybrid membranes were prepared by adding Butyl titanate(TBT) to the casting solutions and hydrolyze simultaneously in the process of membrane formation of L-S phase inversion processes. Different membranes with different content of Ti were prepared, the effect of TBT addtion on the structures and properties of hybrid membranes was aslo studied.PVDF membrane was prepared by L-S phase inversion method. The effect of casting solution composition and casting process on the performance and the structure of PVDF membrane was studied. It results show that with the increasing of PVDF in casting solution, the sponge-type structure at the cross section of the membrane is inhibited, the structure of sublayer undergoes a transition from finger-like pore to sponge-like pore. The hydrophilicity of PVDF membranes improves by blending with polyacrylonitrile(PAN). When polyvinyl pyrrolidone (PVP), polyethylene glycol (PEG) or LiCI was used as additives in casting solution, the pure water flux significantly increases. With the increasing of LiCl content or molecular weight of PEG in casting solution, the pure water flux and the rejection of pepsin increase. Among the membrane made from different casting solutions with solvents of N,N-dimethylacetamide(DMAc), N,N-dimethylformamide(DMF) and N-methyl-2-pyrrolidone(NMP),the water flux of the membrane increases in sequence of DMF