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The formation mechanism of membranes prepared from the crystalline EVAL polymer–water (nonsolvent)–2-propanol (nonsolvent) system

作     者:Young, Tai-Horng Hsieh, Chih-Chen Chen, Li-Yen Huang, Yen-Shih 

作者机构:Institute of Biomedical Engineering College of Medicine and College of Engineering National Taiwan University Taipei 10016 Taiwan 

出 版 物:《Journal of Membrane Science》 

年 卷 期:1999年第159卷第1-2期

页      面:21-27页

核心收录:

学科分类:0703[理学-化学类] 

基  金:NSC 86-2216-E-002-003 

主  题:Cosolvent  Crystallization  Liquid-liquid demixing  Phase diagram Crystallization  Mixing  Morphology  Organic solvents  Phase diagrams  Polyvinyl alcohols  Precipitation (chemical)  Cosolvent  Liquid-liquid demixing  Polyethylene covinyl alcohol  Propanol  Ternary phase diagrams  Polymeric membranes  2 propanol  ethylene vinyl alcohol copolymer  solvent  water  manufacture  membrane technology  article  crystallization  differential scanning calorimetry  membrane formation  membrane structure  phase separation  physical phase  precipitation  priority journal  thermodynamics 

摘      要:Crystalline poly(ethylene-co-vinyl alcohol) (EVAL) membranes from the water-2-propanol cosolvent were prepared by immersion-precipitation at 60°C. The use of two nonsolvents serving as a cosolvent system, replacing the traditional solvent-nonsolvent pair, for the membrane formation was investigated. The two-nonsolvent proportion in which they are mixed to produce the cosolvent system and the prediction of the membrane structures were based on the complex ternary phase diagram at 60°C. It was attempted to relate the influence of liquid-liquid demixing and solid-liquid demixing on the membrane morphologies to the ternary phase diagram. Two different morphologies and two different demixing rates could be obtained by using water and 2-propanol, respectively, to precipitate the cosolvent system. When water was used as the precipitation medium, it showed a rapidly precipitating system and cellular morphologies were obtained due to liquid-liquid demixing. In contrast, when 2-propanol was used as the precipitation medium, it showed delayed demixing and crystallization-induced particulate morphologies were formed. Trends expected on the basis of the phase diagram was in reasonable agreement with the observed membrane morphology. Therefore, the principles of membrane formation established for the ternary systems with nonsolvent-solvent-polymer can be extended to a nonsolvent-nonsolvent-polymer system. Copyright (C) 1999 Elsevier Science B.V.Crystalline poly(ethylene-co-vinyl alcohol) (EVAL) membranes from the water-2-propanol cosolvent were prepared by immersion-precipitation at 60°C. The use of two nonsolvents serving as a cosolvent system, replacing the traditional solvent-nonsolvent pair, for the membrane formation was investigated. The two-nonsolvent proportion in which they are mixed to produce the cosolvent system and the prediction of the membrane structures were based on the complex ternary phase diagram at 60°C. It was attempted to relate the influence of liquid-liquid demixing and solid-liquid demixing on the

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