PVC/PAN共混超滤膜的研究 Ⅱ.铸膜液组成对膜结构与性能的影响

STUDIES ON PVC/PAN BLEND UF MEMBRANE Ⅱ.THE EFFECT OF THE POLYMER-CONCENTRATION OF CASTING SOLUTION ON THE PERFORMANCE AND THE STRUCTURE OF PVC/PAN BLEND UF MEMBRANE

实验表明,铸膜液浓度、PVC 分子量及其分布主要是通过它们对膜孔大小的影响来影响膜的性能。铸膜液浓度提高,膜孔缩小,截留率提高而透水率下降。这种影响在铸膜液百分浓度低于15%时尤为明显。分子量的均一则有利于膜孔的均一。聚乙二醇因其具有较多的羟基,当被添加到PVC/PAN 共混铸膜液中时,既起交联剂的作用,又起溶胀剂的作用,前者有利三维聚合物网络的形成而提高截留率,后者有利提高开放形孔所占的比例而增大透水率。

The experiment shows:(1) The effect of both polymers concentration of casting solution and the molecular weight and its distribution of PVC on the performance of PVC/PAN blend UF membrane mainly depends on their influence on the pore size of membrane.Along with the raising of polymers concentration,the pore size reduces and therefore the rejection increases but the water flux drops,especially when the polymers concentration is lower than 15%.And a uniform molecular weight of PVC is advantageous to form a uniform pore size of membrane;(2) relying on its hydroxyl groups polyethylene glycol added into PVC/PAN casting solution acts as a cross-linking agent and also as a swelling agent and is beneficial to form a space network of polymer and an opening pore structure of membrane respectively,so that it is conducive to both high rejection and high water flux of the membrane.