The film preparation method is as follows: polyamic acid solution is cast into a film, stretched, and then imidized at high temperature. The film is yellow and transparent, with a relative density of 1.39 to 1.45. It has outstanding high temperature resistance, radiation resistance, chemical corrosion resistance and electrical insulation properties. It can be used for a long time in the air at 250 to 280 °C. The glass transition temperatures were 280°C (Upilex R), 385°C (Kapton) and above 500°C (Upilex S), respectively. The tensile strength at 20°C is 200MPa, and it is greater than 100MPa at 200°C. It is especially suitable for use as flexible printed circuit board substrate and various high temperature resistant electrical and electrical insulation materials.

physical properties

Thermoset polyimides have excellent thermal stability, chemical resistance and mechanical properties, usually orange in color. The flexural strength of graphite or glass fiber reinforced polyimide can reach 345 MPa, and the flexural modulus can reach 20GPa. Thermosetting polyimide has small creep and high tensile strength. The use temperature of polyimide covers a wide range, from minus one hundred degrees to two or three hundred degrees.

chemical properties

Polyimide is chemically stable. Polyimide does not require the addition of flame retardants to prevent combustion. Common polyimides are resistant to chemical solvents such as hydrocarbons, esters, ethers, alcohols and fluorochloroalkanes. They are also resistant to weak acids but are not recommended for use in environments with stronger bases and inorganic acids. Certain polyimides such as CP1 and CORIN XLS are soluble in solvents, a property that helps develop their applications in spray coating and low temperature crosslinking.