铸膜溶剂对CAB膜形态和性能的影响

Solvent Effects of Casting Solution on Morphology and Gas Permeation Properties of CAB Membranes

以ＣＡＢ高分子为膜材料，研究了铸膜液的溶剂体系和添加剂对膜形态及选择性渗透Ｎ２、Ｏ２、ＣＨ４、ＣＯ２等气体的影响。溶剂体系以丙酮（ＬｅｗｉｓＢ）为基本组分，混合甲酰胺或乙酸（ＬｅｗｉｓＡ），可得到具有好的气体渗透性或气体选择性的非对称膜。通过溶剂的红外光谱羰基吸收峰的偏移，认为溶剂体系有可能存在Ｌｅｗｉｓ酸∶碱络合物。此外向铸膜液加醇类添加剂可提高膜的透气速率。扫描电子显徽镜显示由丙酮—乙酸—二氧六环溶剂形成的膜是有梯度密度皮层的三层结构非对称膜，ＣＯ２／ＣＨ４选择比高达４５。而由丙酮－甲酰胺－正丙醇体系得到的是海绵状形态大孔隙度的非对称膜。

Using CAB polymer as membrane material,the effects of both the casting solution in consisting of solvent system and additives on membrane morphology and permselectivity to gases (N 2、O 2、CH 4、CO 2) was studied.Based on acetone (Lewis B) as main solvent,solvent systems mixed by formamide or acetic acid (Lewis A) etc. give asymmetric membranes with good gas permeability or gas selectivity. Through the IR spectra shift of carbonyl group of solvent,it is considered that Lewis A∶B complex might be existed.Moreover permeation rate of membranes can be improved if additive (e.s. alcohols) is introduced.SEM photos show that the morphology of membrane formed by acetone-acetic acid-dioxane solution system is a asymmetric trilayer with graded density skin and the selectivity of CO 2/CH 4 is as high as 45. However,the morphology of asymmetric membrane formed by acetone-formamide-n-propanol system is sponge-like shape with large porosity,permeation rate of CO 2 is about 10 -5 cm 3/cm 2.s.cmHg