低温热致相分离法制备聚偏氟乙烯中空纤维多孔膜的研究

Preparation of polyvinylidene fluoride hollow fiber porous membrane via a low thermally induced phase separation

提出了一种低温热致相分离成膜方法(L-TIPS),通过干-湿法纺丝工艺制备了聚偏氟乙烯(PVDF)中空纤维多孔膜,考察了非溶剂致相分离法(NIPS)和热致相分离法(TIPS)两种成膜机理的竞争关系对膜形态结构和性能的影响.结果表明:低温热致相分离法在制备PVDF中空纤维膜的过程中同时发生了非溶剂致相分离机理和热致相分离机理,与单纯非溶剂致相分离机理成膜相比,膜断面未出现大的空穴,仅有少量指状孔,中部为球状结构,内外表面均有皮层,增强了膜的抗污染性能和强度;铸膜液浊点温度与凝固浴温差越大,壁厚越厚,热致相分离作用越明显,非溶剂致相分离作用相对减弱,膜的纯水通量和强度均有所提高,卵清蛋白截留率变化不大;低温热致相分离法比传统热致相分离法制膜温度低,能够添加常用的亲水性高分子添加剂(PVP、PEG、PVA).

In this paper, a low thermally induced phase separation （L-TIPS） method was proposed. Polyvinylidene fluoride （PVDF） hollow fiber porous membranes were prepared by dry-wet spinning technology. The effect of competition of membrane preparing mechanism between a nonsolvent induced phase separation （NIPS） and a thermally induced phase separation （TIPS） on the morphology structure and performance of the membranes was researched. The results showed that TIPS and NIPS occurred simultaneously in the process of L-TIPS; compared with by L-TIPS had no macro-void and presented a few small membrane prepared by NIPS, membrane prepared finger-like pores, globusity structure in the middleand skin layers in the inside and outside surfaces, so this sructure strengthened the antipollution performance and strength of the membrane. The effect of TIPS was more evidence and the effect of NIPS was weaker if the difference between cloud point of spinning dope and coagulation temperature became bigger and membrane thickness became thicker, the results were that the pure water flux and strength of the membrane were all improved, the rejection of egg albumin had no evidence change. The spinning dope tempreture of L-TIPS was lower than spinning dope tempreture of traditional TIPS, so some hydrophilic polymeric additives （PVP.PEG.PVA） in common use could add to the spinning dope.