1, wholly aromatic polyimide by thermal gravimetric analysis, it begins the decomposition temperature is generally about 500 ℃. Biphenyl dianhydride and
P-phenylenediamine synthetic polyimide, the thermal decomposition temperature of 600 ℃, is one of the highest in the thermal stability of the polymer species so far. 2, polyimide can withstand very low temperatures, such as liquid helium will not rattle in the -269 ℃. 3, the polyimide having excellent mechanical properties, tensile strength unfilled plastics are 100Mpa or more, pyromellitic polyimide film (Kapton) is 170Mpa or more, and biphenyl type polyimide ( Upilex S) reaches 400Mpa. As a plastic, elastic modulus usually 3-4Gpa, fiber can reach 200Gpa, according to theoretical calculations, pyromellitic dianhydride and p-phenylenediamine synthetic fiber up 500Gpa, second only to carbon fiber. 4, a number of varieties of polyimide is insoluble in organic solvents, acid stable, generally little hydrolysis varieties, this seemingly shortcoming performance while filling the polyimide is different from a lot of other high-performance polymers characteristics, i.e., the raw material can be recovered by alkaline hydrolysis dianhydride and a diamine, for example, Kapton film having a recovery of up to 80% -90%. Changing the structure can be obtained quite hydrolysis resistant varieties, such as withstand 120 ℃, 500 小时 boiled. 5, the thermal expansion coefficient of the polyimide in 2 × 10-5-3 × 10-5 ℃, wide as the thermoplastic polyimide 3 × 10-5 ℃, biphenyl up 10-6 ℃, individual species can up 10-7 ℃. 6, polyimide has a high resistance to radiation performance, the film after 5 × 109rad fast electron irradiation strength retention rate of 90%. 7, the polyimide having good dielectric properties, dielectric constant of about 3.4, the introduction of fluorine, or dispersed in a nano-sized air polyimide, the dielectric constant can be reduced to about 2.5. Dielectric loss 10-3, a dielectric strength of 100-300KV / mm, wide as the thermoplastic polyimide 300KV / mm, volume resistivity of 1017Ω / cm. These properties over a wide temperature range and frequency range can maintain at a high level. 8, polyimide polymer is self-extinguishing, fuming rate. 9, polyimide in a high vacuum gas rarely decentralized. 10, polyimide non-toxic, used to make cutlery and medical equipment, and can withstand thousands of sterilization. Some polyimide also has good biocompatibility, for example, in blood compatibility test non-hemolytic, non-toxic in vitro cytotoxicity experiments.