1, the whole aromatic polyimide according to Thermogravimetric analysis, its start decomposition temperature is generally around 500 ℃. Polyimide, synthesized by phthalic anhydride and diphenyl diamine, has a thermal decomposition temperature of 600 ℃, which is one of the highest thermal stability in polymers so far.
2, polyimide can withstand extremely low temperature, such as in 269 ℃ liquid helium will not be brittle crack.
3, Polyimide has excellent mechanical properties, the tensile strength of the unfilled plastic is above 100Mpa, the benzene-type polyimide film (Kapton) is more than 170Mpa, Hangzhou plastic au special thermoplastic polyimide (TPI) impact intensity up to 261kj/m2. Biphenyl-Type polyimide (Upilex S) reached 400Mpa. As engineering plastics, the elastic modulus is usually 3-4gpa, the fiber can reach 200Gpa, according to theoretical calculations, phthalic anhydride and benzene diamine synthesized fiber up to 500GPA, after carbon fiber.
4, some of the polyimide varieties insoluble in organic solvents, for dilute acid stability, the general variety is not resistant to hydrolysis, this seemingly weak performance makes polyimide differs from other high-performance polymers a very large feature, that is, alkaline hydrolysis can be used to recover raw anhydride and two amine, for example, for Kapton film, its recovery rate of up to 80 %-90%. Changes in the structure can also be very resistant to hydrolysis of varieties, such as withstand 120 ℃, 500 hours of water boiling.
5, Polyimide thermal expansion coefficient in 2x10-5-3x10-5℃, Nanjing Yeuzi Chemical Yzpi thermoplastic polyimide 3x10-5℃, biphenyl type up to 10-6 ℃, individual varieties up to 10-7 ℃.
6, Polyimide has a very high radiation resistance, the film in the 5x109rad fast electron irradiation after the strength of the retention rate of 90%.
7, Polyimide has good dielectric properties, dielectric constant of about 3.4, the introduction of fluorine, or the air nanometer size dispersed in polyimide, the dielectric constant can be reduced to about 2.5. Dielectric loss of 10-3, dielectric strength of 100-300kv/mm, widely into thermoplastic polyimide as 300kv/mm, volume resistance is 10∧17ω cm. These properties remain at a high level in a wide range of temperatures and frequencies.
8, Polyimide is a self quenching polymer, the smoke rate is low.
9, polyimide in the very high vacuum low down.
10, Polyimide non-toxic, can be used to make tableware and medical equipment, and withstand thousands of times disinfection. Some polyimide also has good biocompatibility, for example, in the blood compatibility Experiment for non hemolytic, in vitro cytotoxicity experiments are non-toxic.