| Poly(vinylidene chloride-vinyl chloride)(P(VDC-VC))is a semicrystalline polymer with good toughness and high temperature resistance,which is rarely reported in literatures.In this paper,P(VDC-VC)porous membranes were prepared by nonsolvent induce phase separation method using P(VDC-VC)as the membrane-forming polymer.The effects of membrane formation conditions on membrane structure and properties were analyzed and discussed.Firstly,the P(VDC-VC)flat membrane was prepared by nonsolvent induce phase separation method using P(VDC-VC)as the membrane-forming polymer and N,N-dimethylacetamide(DMAc)as the solvent.The results showed that the obtained P(VDC-VC)flat membrane consists of a surface skin layer and a cross-section macroporous support layer,showing an asymmetric membrane structure.The increase of the concentration of polymer or the increase of the coagulation bath temperature can improve the degree of dense of P(VDC-VC)flat membrane surface,improve the rejection rate of bovine serum albumin(BSA)and membrane flux recovery more than 90%.The membrane permeation performance is better under low coagulation bath temperature.The mechanical properties increase with the increase of polymer concentration and polymer molecular weight,and decrease with the increase of coagulation bath temperature.Secondly,P(VDC-VC)flat membrane was prepared by s nonsolvent induce phase separation method using polyethylene glycol(PEG)and nano-silica(SiO2)as modifiers.The morphology and pore structure of the membrane were controlled by adjusting the content of PEG and SiO2.The results showed that the hydrophilicity of P(VDC-VC)was improved by PEG,and the membrane flux increased first and then decreased with the increase of PEG content.The P(VDC-VC)/SiO2 hybrid membrane was prepared by adding SiO2,and the hydrophilicity and permeability of the porous membrane were improved obviously by the addition of SiO2.The rejection rate was 93.3%.Finally,P(VDC-VC)hollow fiber membranes were prepared by dry-wet spinning.The effects of membrane formation conditions and nano-SiO2 content on the structure and properties of hollow fiber membranes were studied.The results showed that the hollow fiber membrane obtained from low temperature(12.0℃)P(VDC-VC)casting solution entering into high temperature(40.0 ℃)coagulation bath had inner and outer double cortical structure.When the content of nano-SiO2 was 1.0wt%,the pure water flux was up to 249.2L·m-2·h-1,and the rejection rate of BSA solution was 94.6%. |
