热致相变分离法制备PVDF微孔膜及其性能研究

Preparation and Characterization of PVDF Microporous Membrane via Thermally Induced Phase Separation Method

摘要:

本以邻苯二甲酸二甲酯（DMP）为稀释剂，聚偏氟乙烯（PVDF）为原料，通过热致相变分离法，制备了PVDF微孔膜。采用扫描电镜（SEM）、差示扫描量热法（DSC）、拉伸压缩材料试验机等手段对PVDF微孔膜的性能及热力学特征进行了表征。结果表明：DMP作为稀释剂时与PVDF有很好的相容性；铸膜液中DMP质量分数由50%增加到80%时，PVDF微孔膜的纯水通量和孔隙率分别由65 L/(m2?h)和34%增加到230 L/(m2?h)和77%，分别增加了135%和254%；而随着铸膜液中DMP含量的上升，PVDF微孔膜的断裂伸长率以及断裂强度都是逐渐下降的；此外，用有机非溶剂处理微孔膜后，膜通量可以提高3~4倍；同时，热力学研究表明当DMP含量不断上升时，PVDF结晶颗粒变得越来越模糊，而且球晶之间的空洞变大，球晶间的结合则更为稀疏，球晶尺寸也呈现出了变小的趋势。

Abstract:

Polyvinylidene fluoride (PVDF) microporous membrane was prepared using PVDF as raw material and dimethyl phthalate as diluents through thermally induced phase separation (TIPS) method. The properties and thermodynamic features of PVDF microporous membrane were characterized by scanning electron microscope (SEM), differential scanning calorimetry (DSC) and tensile strength test. The results indicated that DMP had an excellent compatibility with PVDF. When the DMP contents increased from 50% to 80%, the pure water flux and the porosity of PVDF microporous membrane improved from 65 L/(m2?h) and 34% to 230 L/(m2?h) and 77%. While the breaking tensile strength and breaking elongation of the microporous membrane decreased gradually along with the increase of DMP content. Moreover, the pure water flux of PVDF membrane improved by 3~4 times in dealing with organic solvents. Meanwhile, thermodynamic study showed that with the DMP contents increased, PVDF crystal grain became more and more fuzzy and the cavity between spherocrystal became bigger, and the spherocrystal size presented a descendant tendency.