Polyimide: the Top of the Pyramid of Polymer Materials!
Ⅰ. Introduction to polyimide
Polyimide (PI) is an aromatic heterocyclic polymer compound with imide chain links in its molecular structure. It is one of the best heat-resistant varieties in engineering plastics and is widely used in aviation, aerospace, microelectronics, Nano, liquid crystal, laser and other fields.
Recently, all countries are listing the research, development and utilization of PI as one of the development priorities of new chemical materials in the 21st century. Polyimide, because of its outstanding characteristics in performance and synthesis, has great application prospects whether it is used as a structural material or as a functional material.
Polyimide is known as the top material of the pyramid of polymer materials, also known as "problem-solving expert", and even some people in the industry believe that "without polyimide, there would be no microelectronics technology today".
Ⅱ. Classification and application of polyimide
Due to its excellent performance, polyimide can be used in many fields and can also be divided into various types, including engineering plastics, fibers, photosensitive polyimides, foam materials, coatings, adhesives, films, aerogels, composites materials etc.
Among the many polymers, polyimide is the only polymer that has a wide range of application fields and shows outstanding performance in each application field. Below, we will take you to understand the main uses of various varieties of polyimide.
1. Engineering plastics
Polyimide engineering plastics can be divided into both thermosetting and thermoplastic, and can be divided into polypyromellitic imide (PMMI), polyetherimide (PEI), polyamide-imide (PAI), etc. They have their own uses in different fields.
PMMI has a thermal deformation temperature of 360°C under a load of 1.8MPa, and has excellent electrical properties. It can be used for precision parts under special conditions, high temperature resistant self-lubricating bearings, sealing rings, blower impellers, etc., and can also be used for valve parts in contact with liquid ammonia. , Jet engine fuel supply system parts.
PEI has excellent mechanical properties, electrical insulation properties, radiation resistance, high temperature resistance and wear resistance, good melt fluidity, and a molding shrinkage rate of 0.5% to 0.7%. It can be molded by injection and extrusion, and post-processing is easier. It can also be combined with other materials by welding, and is widely used in industries such as electronic appliances, aviation, automobiles, and medical equipment.
The strength of PAI is the highest among current non-reinforced plastics, with a tensile strength of 190MPa, a bending strength of 250MPa, and a heat distortion temperature of 274°C under a load of 1.8MPa. PAI has good ablation resistance and electromagnetic properties under high temperature and high frequency, and has good bonding performance to metals and other materials. It is mainly used for gears, bearings and copier separation claws, etc. It can also be used for ablation of aircraft materials, magnetically permeable materials and structural materials.
2. Polyimide fiber
Polyimide fiber is an important high-performance fiber. Its high-temperature-resistant polyimide fiber is one of the organic synthetic fibers with the highest service temperature at present. It can be used at 250~350°C. Compared with aramid fiber and polyphenylene sulfide fiber, it is superior in terms of heat and other aspects. The strength of high-performance polyimide fiber is about 1 times higher than that of aramid fiber. It is one of the organic synthetic fibers with the best mechanical properties at present.
With the continuous development of high-tech fields, the requirements for the physical and chemical properties of PI products are also getting higher and higher. The performance of traditional PI materials in terms of mechanics, heat, light, electricity, and magnetism can no longer meet the special requirements of materials in the field of modern science and technology. Requirements, PI high-performance fiber will become a typical representative of the next generation of high-performance fiber due to its superior mechanical properties, heat resistance stability, radiation resistance and other characteristics.