Study on the evolution of reinforced PVDF hollow fiber membrane morphology and strong hydrophobicity

摘要

Reinforced polyvinylidene fluoride (PVDF) hollow fiber membranes that contained hollow braided tube and coated surface were prepared by concentric circles spinning method. The braided tube was prepared by two-dimensional braided technique using polyester (PET) filaments, while PVDF as the coated surface was obtained by nonsolvent-induced phase separation method. The effects of vapor-bath time on the structure and morphology of hollow fiber membrane were investigated, and the results could be concluded: (1) Extension of vapor-bath time would induce the roughness of coated surface which was observed by atomic force microscopy (AFM). When the vapor-bath time was 18 h, the static water contact angle reached as high as 139.2 degrees; (2) Not only the porosity but also the mean pore size of the hollow fiber membranes was promoted as the increase of vapor-bath time. However, the liquid entrance pressure decreased obviously; (3) The characterization of membranes' cross-section morphologies disclosed that the evolution of pore's morphology switched from finger-like to spongelike when the coagulation condition changed.