Polyimide possesses excellent physical properties, the macroscopic manifestations of which are closely related to the rigid imide rings and aromatic backbone in its molecular structure. This type of material is typically a yellow to brownish-yellow solid and can be processed into various forms such as films, fibers, bulk materials, and coatings, with polyimide films being the most widely used.
In terms of thermal properties, polyimide exhibits high thermal stability and a high glass transition temperature (Tg). Most varieties maintain structural stability and performance integrity even at high temperatures, and have a relatively high thermal decomposition temperature. Its low coefficient of linear thermal expansion and good dimensional stability during temperature changes make it suitable for applications requiring high precision.
In terms of mechanical properties, polyimide possesses high tensile strength and elastic modulus, while also exhibiting certain toughness and fatigue resistance. Different structural types of polyimide exhibit differences in rigidity and flexibility, which can be adjusted through molecular design.
In terms of electrical properties, polyimide possesses low dielectric constant and dielectric loss, as well as excellent electrical insulation properties, maintaining stable electrical performance over a wide frequency and temperature range. Therefore, it is widely used in electronic and electrical insulation fields.
Furthermore, polyimide exhibits low density and good radiation resistance, demonstrating good stability in space and high-energy environments. While it does exhibit some hygroscopicity, the impact of moisture absorption on performance can be reduced to some extent through structural design and material modification.
