Discussing physical aging phenomenon of polyimide gas separation membranes
As an emerging technology,membrane-based gas separation has received widespread attention.Aromatic polyimide is one of the most promising materials for gas separation membranes.Currently,polyimide with various structures has been developed and researched on laboratory scales.However,in situations of industrial application,the physical aging phenomenon of membrane materials during long-term operation significantly affects the accurate evaluation of gas separation performance and the reasonable design of process parameters.The current research status of the physical aging behavior of polyimide thin films and asymmetric membranes was reviewed,the aging mechanism and models proposed by predecessors were summarized,the main factors affecting the aging process were analyzed and the prevention methods of physical aging were proposed.The characteristics of polyimide used for gas separation membranes that were not prone to aging included high molecular chain rigidity,limited chain space configuration,and appropriate inter-chain interactions.Future research was expected to focus on not only developing new structures of polyimides as well as crosslinking agents,but also preparation process optimization.
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