热致相分离法平片式聚(乙烯-乙烯醇)微孔膜的制备和表征

以丙三醇为稀释剂，用热致相分离方法(TIPS)制备了无纺布支撑的平片式聚(乙烯-乙烯醇)(EVOH)微孔膜。实验研究了冷却速率及EVOH初始浓度对膜结构及性能的影响，测定了EVOH／丙三醇体系的相图．用扫描电子显微镜(SEM)及泡点法表征了微孔膜的微观结构及表面孔径，同时测试了膜的纯水通量。结果表明，随着冷却速率的加快，结晶曲线向低温移动。EVOH初始浓度决定了体系的相分离方式．由液-液相分离及固-液相分离机理形成的膜分别具有花边结构与球间缝隙结构；冷却速率影响膜的孔径大小和形态。随着冷却速率及EVOH初始浓度的降低，膜的孔径及纯水通量均逐渐增大。

Preparation and Characterization of Poly(ethylene-co-vinyl alcohol)(EVOH) Flat Sheet Microporous Membranes via Thermally Induced Phase Separation

Microporous membranes supported on the non-woven fabrics were prepared by the crystalline poly(ethylene-co-vinyl alcohol)(EVOH) via thermally induced phase separation, using the glycerol as diluent. In this paper the diagram of the EVOH/glycerol system was determined. The influence of some factors as concentration and cooling rate on the performance and the morphology was investigated. The results showed that the crystallization curve shiftes to low temperature with the decrease of cooling rate. The polymer concentration determines the mode of phase separation. Liquid-liquid phase separation resultes in leafy structure and solid phase separation resultes in spherulite structure. The porosity and the diameter of pores increase when the cooling rate and the initial concentration decreased. The water permeability increase when the diameter of pores increases.