First,Good performance of temperature
1.The decomposition temperature degree generally at 500 ℃. From two to two of benzene anhydride and diphenyl amine synthesis of polyimide, thermal decomposition temperature reaches 600 ℃, is by far one of the highest thermal stability of the polymer in varieties. Thermosetting can use stable at 360 ℃, thermoplastic can be used for a long time at 230 ℃.
2.While resistant properties of very low good, if still not in liquid nitrogen - 269 DEG C in brittle fracture.
3.The thermal expansion coefficient is very low, only 2X 10-5- 3 X10-5/ ℃, biphenyl type is 10- 6/ ℃, individual species can reach 10- 7/ C.
Second,Excellent mechanical properties
1.Polyimide has good mechanical properties. Tensile strength of polyimide plastic unfilled are 100MPa above, as engineering plastics, its elastic modulus is usually 3- 4GPa. Strength, modulus of fiber reinforced PI plastic could be further enhanced
2.Polyimide has excellent wear resistance, self lubrication performance. The change of mechanical properties with temperature fluctuation is small, high temperature creep, the creep speed even than the aluminum is also small. Do the mechanical transmission parts.
3.Polyimide heat aging performance is good, with 200 ℃, 1500h aging treatment, the measured tensile strength decreased little materials at room temperature.
4.The radiation resistance, such as polyimide films in 5 × 109rad dose irradiation, strength remains at 86%, polyimide fiber 1 * 109rad dose irradiation, the strong keeping rate of more than 90%. Can be used in the nuclear industry.
Third,Have good dielectric properties and electrical properties
Dielectric constant polyimide as 3.4 , introducing fluorine or air dispersed in the polyimide nano size, dielectric constant can be reduced to about 2.5 . The dielectric loss of 10-3, dielectric strength of 100- 300kV/ mm, volume resistance is 10^17 ohm / cm. These properties can still maintain higher in the wide temperature range and frequency range level.
Corona resistant performance, excellent electrical insulation properties
Forth,Stable chemical properties
Polyimide has excellent oil resistance and organic solvent resistance,Resistance to hydrolysis by dilute sulfuric acid, water stability, 500h stand up to 120 ℃.Not resistant to concentrated sulfuric acid, concentrated nitric acid, Non alkali solution and high temperature steam.
Fifth,Flame retardant property
Polyimide polymer self quenching, smoking rate is low, the high vacuum outgassing rarely; stability in high temperature, high vacuum and irradiation, volatile matter little; flame retardant grade: V0; LOI >45
Can be used for the manufacture of tableware and medical equipment, and can withstand sterilization thousands of times, some polyimide has good biocompatibility. For example, in the blood compatibility test for non hemolytic, cytotoxic activity in vitro experiments for non-toxic. text-indent:0;mso-list:l0 level1 lfo1'>10.Polyimide is non-toxic, can be used for the manufacture of tableware and medical equipment, and can withstand thousands of times disinfection. There are some polyimide has good biological compatibility, for example, in the blood compatibility test for non hemolytic, cytotoxic activity in vitro experiments for non-toxic.