1. For the wholly aromatic polyimide, according to thermogravimetric analysis, it begins the decomposition temperature is generally about 500 ℃, biphenyl dianhydride and p-phenylenediamine synthetic polyimide, the thermal decomposition temperature of 600 ℃, variety is one of the highest thermal stability of polymers so far.
2. The polyimide can withstand very low temperatures, such as in the thermodynamic temperature 4K (-269 ℃) liquid helium is still not rattle.
3. Polyimide also has good mechanical properties. Tensile strength unfilled plastics are above 100MPa,pyromellitic polyimide film (Kapton (R)) of 250MPa, and biphenyl type polyimide film (Upilex) reach 530MPa. Engineering plastic, the elastic modulus is generally 3 ~ 4GPa, as reported by Russian scholars copolyimide spun fiber tensile strength of up to 5.1 ~ 6.4GPa, the elastic modulus to 220 ~ 340GPa. According to theoretical calculations, the pyromellitic dianhydride and p-phenylene diamine polyimide synthetic fiber elastic modulus up to 500 GPa, carbon fiber behind.
4. Polyimide of acid stable; but the general quality of impatience hydrolysis, especially in alkaline hydrolysis. The disadvantage of this seemingly performance is given a polyimide different from other high-performance polymers great feature, that can make use of recycled raw materials alkaline hydrolysis dianhydride and a diamine, for example, Kapton film having a recovery of up to 90%. Changing the structure can be obtained relatively hydrolysis species, such as boiled withstand 500h at 120 ℃. However, other aromatic polyimide polymer as intolerant of concentrated sulfuric acid, concentrated nitric acid and halogens.
5. Polyimide has a wide spectrum of solubility, depending on the configuration, some breeds almost insoluble in all organic solvents, others are soluble in common solvents (e.g., tetrahydrofuran, acetone, chloroform, or toluene and methanol).
6. The thermal expansion coefficient of the polyimide in 2 × 10-5~ 3 × 10-5 / ℃, biphenyl type polyimide up to 10-6 / ℃, and metal on the same level, as well as individual species can even reach 10-7 / ℃.
7. Polyimide has a high resistance to radiation performance, the film absorbed dose of 5 × 107Gy still maintain strength at 86%,polyimide fibers with a 1 × 108Gy after their fast electron irradiation strength retention rate is still 90%.
8. Polyimide has good node performance, ordinary aromatic polyimides relative dielectric constant of about 3.4. Introduction of fluorine, Acer or the large sides of the air dispersed in nanometer size in the polyimide, the relative dielectric constant can be reduced to about 2.5, a dielectric loss of 10-3, node strength of 100 ~ 300kV / mm, volume resistivity of 1017Ω • cm. These properties over a wide temperature range and frequency range can maintain at a high level.
9. Polyimide polymer self-extinguishing, low smoke.
10. Polyimide high vacuum gas rarely decentralized.
11. Polyimide non-toxic, it can be used to make tableware and medical equipment, and can withstand thousands of sterilization. Some polyimide also has good biocompatibility, for example, the non-hemolytic blood compatibility test; vitro cellular toxicity test.