Overview of polyimide microporous membrane

Polyimide filtration membrane refers to a membrane made of polyimide, because polyimide is a high-performance polymer with excellent thermal stability, chemical resistance and mechanical strength. In normal production, polyimide is synthesized by a two-step process involving the reaction of dianhydride and diamine to form an imide bond. This type of membrane material is widely used in the fields of aerospace and electronics.

What kind of molecular structure does polyimide film have?

As mentioned above, polyimide film forms imide bonds through the reaction of dianhydride and diamine. The imide group (-C(O)N-) is the key structural feature of polyimide. These bonds form a cross-linked three-dimensional network structure, which is an important reason for its thermal stability and chemical resistance. The aromatic skeleton composed of alternating aromatic rings connected by imide bonds can provide the film with excellent mechanical strength, rigidity and deformation resistance. At the same time, flexible segments are also contained between the imide bonds. These flexible segments provide flexibility to the film and enable it to be processed into various forms, such as films or coatings. And the extended conjugation formed by the alternating arrangement of aromatic rings in the skeleton gives the film unique high resistivity and transparent optical properties.
Because the molecular structure of polyimide film will also be different due to the selection of dianhydride and diamine used in its synthesis, as well as the modification or additives introduced during the manufacturing process, the polyimide film has different properties and performance characteristics that can be customized for specific applications.

What temperature can polyimide film withstand?
Polyimide film has excellent high temperature resistance and is durable enough to withstand high temperatures without significant degradation or loss of performance. The main reason is its high glass transition temperature (Tg) and thermal stability. The typical Tg range is about 250°C to 350°C. Under normal circumstances, it can operate continuously at 200°C to 300°C without significantly affecting its performance. That is to say, at temperatures below Tg, polyimide film can maintain its rigid state and mechanical properties. However, it should be noted that it will soften above Tg after testing, so its mechanical properties will also be affected. Based on these excellent properties, polyimide film is often used as an insulating material in electronic and electrical components. It can provide electrical insulation and thermal protection, including thermal blankets and protective coatings in aerospace applications, and can withstand extreme temperatures encountered during space missions.

What is the density of polyimide film?
The density of polyimide film is not a fixed value. It depends on its specific formula and manufacturing process, such as the type and concentration of polyimide precursor, the use of fillers or additives, and the thickness of the film. In general, the average density of polyimide film is about 1.3 g/cm³ to 1.5 g/cm³. From the data, polyimide film should be a lightweight material due to its low density, which is why it is widely used in aerospace, electronics and flexible electronic products.

In short, as a special material, polyimide film is widely used in many fields such as aviation, aerospace, electrical/electronics, microelectronics, nano, liquid crystal, separation membrane, laser, locomotive, automobile, precision machinery and automatic office machinery. Countries around the world have listed the research, development and utilization of polyimide as one of the most promising engineering plastics. Due to its outstanding characteristics in performance and synthesis, its huge application prospects have been fully recognized whether as a structural material or as a functional material.