Effect of PVP molecular weights on structures and properties of PVDF membranes

PVDF membranes were prepared via phase inversion process from casting solution composed of polyvinylidene fluoride(PVDF),dimethylacetamide(DMAc),and polyvinylpyrrolidone(PVP)of different molecular weights.The effect of PVP molecular weights on morphology and performance was investigated.It was found that with increase in PVP molecular weight the water flux rised firstly,and then decreased.When PVP 58000and PVP 230000were used as additives,the water flux was much higher than PVP 10000and PVP 780000,and macrovoids existed.The hydrophilicity of the membranes was also examined.It was found that PVP with high molecular weight was partially entrapped in the pores.It was proved that the entrapped PVP was proven to enhance the hydrophilicity of the membranes.The antifouling performance of membranes with PVP 230000as additive was best,and the steady permeability of bovine serum albumin(BSA)solution reached 120L/(m2.h.0.1MPa)approximately.