What is polyamide?

What is polyimide?

Performance Characteristics

1. Heat resistance:

Polyimide has extremely strong heat resistance. TGA thermogravimetric analysis shows that the decomposition temperature of polyimide can reach 500℃-600℃. It is one of the most stable polymers at this stage. 
 

2. Low temperature resistance

3. Good mechanical properties:

The tensile strength of homophenylene polyimide film (Kapton) is 170 MPa and the tensile modulus is 3.0 GPa, while the tensile strength of biphenyl polyimide (Upilex) reaches 400 MPa and the tensile modulus It is 3 ~ 4 GPa, and can be greater than 200 GPa after enhancement.

4. Good dimensional stability:

Polyimide material has an extremely low thermal expansion coefficient. The thermal expansion coefficient is generally 2×105 ~ 3×10-5/℃. The thermal expansion coefficient of biphenyl polyimide is 1×10-6/℃. The thermal expansion of individual products The coefficient can be 1×10-7/℃, which is close to the thermal expansion coefficient of metal. It is precisely because of this low thermal expansion coefficient that PI can be widely used in the manufacturing of flexible printed circuit boards.

5. Good dielectric and insulation properties:

The dielectric constant of polyimide materials is generally between 3.0 and 3.6. When fluorine atoms are introduced or nanoscale air is dispersed in it, the dielectric constant can be reduced to between 2.5 and 2.7, or even lower. The dielectric loss is about 1×10-3, the dielectric strength is 100 ~ 300 Kv/mm, and the volume resistance is 1×1017 Ω.cm. This low dielectric constant polyimide provides a guarantee for its application as packaging materials and insulating materials in the microelectronics industry.

6.Good radiation resistance:

Polyimide materials are stable under high temperature, high vacuum and irradiation, and have low volatile matter.

7.Good chemical stability:

Usually polyimide is insoluble in common organic solvents, and common soluble polyimide is only soluble in some specific polar organic solvents. However, polyimide, like other aromatic polymers, is not resistant to concentrated sulfuric acid and concentrated nitric acid. and halogens. Polyimide has strong hydrolysis resistance to dilute acids and high stability to oxidants and reducing agents, especially at high temperatures. But general varieties are not resistant to hydrolysis, especially alkaline hydrolysis.

8.Good flame retardancy:

Polyimide is a self-extinguishing polymer with a very low smoke rate. The carbon residue rate after high-temperature combustion is often more than 50%. It is a good heat retardant and flame retardant.

9.Non-toxic and biocompatible:

Polyimides are non-toxic, and some polyimides are also very biocompatible. Polyimide can be used to make tableware and medical equipment and can withstand thousands of sterilizations.

10.Polyimide also has its shortcomings:

Traditional polyimide is infusible and difficult to process, the film is hard, brittle, and has poor strength; when used in the microelectronics industry, its thermal expansion coefficient is not good. In the optical communication industry, its transparency is poor; at the same time, its adhesion is not very good.

Polyimide Synthesis method

Polyimide Type