Polyimide is one of the best comprehensive properties of organic polymer materials, high temperature 400 ℃, long-term use temperature range of - 200 to 300 DEG C, no obvious melting point, high insulation resistance, dielectric constant of 4 to 103 Hz, the dielectric loss is only 0.004 ~ 0.007, F to H grade insulation material.
PI refers to the large backbone containing acyl imino polymer, which belongs to the aromatic compounds, is composed of two yuan and two yuan amine anhydride prepared by condensation polymerization. The molecular chain of PI contains a large number of benzene ring, and imide groups were incorporated into the benzene ring and the formation of five membered heterocyclic rings, the rigidity of the molecular chain, intermolecular forces strong, packing density is high, the PI has a series of excellent properties. PI due to its structure consisting of two anhydride and two amine is not the same, performance is also somewhat difference.
Polyimide is a kind of special engineering material, has been widely used in aviation, aerospace, microelectronics, nanotechnology, liquid crystal, separation membrane, laser fields. Recently, all countries in the research, development and utilization of polyimide included in twenty-first Century the most promising one of Engineering plastics. Polyimide, because of its outstanding characteristics of property and synthesis, both as a structural material or as a functional material, its huge application prospect has been fully understood, known as the "problem solver", and that "no polyimide would not have today's Microelectronic technology".
Polyimide is aromatic heterocyclic polymer molecular structure of the compounds containing imide group chain, English Polyimide (PI), can be divided into benzene PI, soluble PI, polyamide imide (PAI) and polyether imide (PEI) four.
PI is one of the best varieties of heat-resistant engineering plastics at high temperature, some varieties may be long withstand the high temperature of 290 ℃ short time under 490 ℃, the mechanical properties, fatigue resistance, flame retardant electrical properties, dimensional stability, good, molding shrinkage of small, oil resistance, acid and organic solvents, not alkali resistance, excellent resistance to friction, wear performance.
Thermoplastic polyimide resin (Polyimide resin), referred to as PI) is a thermoplastic engineering plastics. It is high temperature resistant thermoplastic plastics, with high glass transition temperature (243 DEG C) and melting point (334 ℃), heat deformation temperature up to 260 ℃ (30% glass fiber or carbon fiber reinforced grade), can be used for a long time at 250 ℃, and other high temperature resistant plastic as compared with PEEK, PPS PTFE, PPO, etc., the use of the upper limit of the temperature higher than the nearly 50 ℃;
PI resin not only heat resistance than other high temperature resistant plastic is excellent, and has the advantages of high strength, high modulus, high fracture toughness and excellent dimensional stability; PI resin can maintain high strength at high temperatures, its bending strength at 200 ℃ up to about 24MPa, at 250 ℃ bending strength and compression strength is still 12 ~ 13MPa; PI resin's rigidity, good size stability, low coefficient of linear expansion, very close to the metal aluminum material;
Excellent chemical resistance, the chemicals in general, only the concentrated sulfuric acid to dissolve or destroy it, its corrosion resistance and nickel steel are similar, and their flame retardant, flame conditions in the release of smoke and toxic gases, anti radiation ability; PI resin has good toughness, the alternating stress and excellent fatigue resistance is the most outstanding all plastic, alloy material with comparable;
The tribological properties of PI resin with outstanding resistance to sliding wear and fretting wear, excellent performance, especially to maintain high wear resistance and low friction coefficient at 250 ℃; PI resin easy extrusion and injection molding, excellent machining performance, high molding efficiency.
In addition, PI also has self lubrication, easy processing, insulation stability, hydrolysis resistance and other excellent performance, which is widely used in aerospace, automotive, electrical and electronic, medical and food processing and other fields, development and utilization prospects.