粉体辐射接枝丙烯酸的聚偏氟乙烯超滤膜的制备

采用粉体辐射接枝丙烯酸的聚偏氟乙烯(PVDF-g-PAA)为材料,以浸没沉淀相转化法制备PVDF-g-PAA超滤膜,研究了接枝后材料溶解性能的变化、以及溶剂种类、聚合物浓度、添加剂种类及浓度、凝胶浴温度制膜参数对PVDF-g-PAA膜结构及性能的影响.结果表明:辐射接枝丙烯酸后,聚合物的溶度参数增大,同时聚合物的极性也增强.在溶剂影响的考察中,以二甲基甲酰胺(DMF)和N-甲基吡咯烷酮(NMP)为溶剂制备的PVDF-g-PAA膜表面致密,透过通量小,对牛血清蛋白(BSA)截留率高;而以二甲基亚砜(DMSO)为溶剂制备的PVDF-g-PAA膜表面孔径较大,透过通量最大,对BSA截留率迅速下降;聚合物浓度的增加使得PVDF-g-PAA膜结构更加致密,纯水通量降低,截留率增加;随着添加剂PEG400浓度的增加,PVDF-g-PAA膜透过通量增加,膜的皮层多孔性增加,厚度增加,大孔发生的起始点向膜内部迁移;在考察的温度区间内(12～23℃),随着凝胶浴温度的升高,PVDF-g-PAA膜通量变大,截留率降低.

Preparation of PVDF-graft-poly(acrylic acid) UF Membranes

PVDF-graft-poly(acrylic acid)(PVDF-g-PAA) was used as the material to prepare UF membrane via the phase inversion method.The solubility parameter of PVDF-g-PAA was tested.The effects of the type of solvents,polymer concentration,additives concentration,as well as the temperature of coagulation bath on the performance and structure of the PVDF-g-PAA membranes were discussed.The results showed that after being grafted with acrylic acid,the solubility parameter of PVDF-g-PAA was increased and the polarity of this polymer was enhanced.When DMF or NMP was used as solvent in the preparation of UF membranes,the membrane had a denser skin layer,a lower water flux and a higher rejection of BSA;when DMSO was used as solvent,there were some larger pores distributed on the membrane surface layer,and the membrane had the highest water flux and the lowest rejection of BSA;with the increase in the polymer concentration,the membrane structure became denser,the water flux decreased and the rejection of BSA increased;the increase in PEG400 concentration would lead to an increase in membrane flux and a more porous surface layer.Moreover,the thickness of the membranes also increased,and the starting position of macrovoids shifted further into the membranes;within the temperature range of 12~23 ℃,with the increase in temperature,the flux of the membrane increased,and the rejection of BSA decreased.