What are the main methods to improve the atomic oxygen resistance of polyimide?

So far, the main methods to improve the atomic oxygen resistance of polyimide are: composite method, filling method and chemical modification method. Although the composite method and the filling method can effectively improve the atomic oxygen resistance of polyimide, they still have great limitations. The chemical modification method focuses on the polyimide molecular chain and aims to improve the atomic oxygen resistance of polyimide at the molecular level.

It has the advantages of high efficiency and good uniformity. At present, elements such as phosphorus, silicon, and zirconium are mainly introduced into the pi molecular chain to improve the performance of proton oxygen. Considering the economic benefits and comprehensive properties of modified polyimide, silicon is often introduced into the molecular chain.

Compared with traditional linear polymer modifiers, hyperbranched polysiloxanes have a special hyperbranched structure, so they have been improved in terms of reducing polymer viscosity, crystallinity, intermolecular chain entanglement and improving polymer solubility. Wide range of applications. Its special hyperbranched structure can be loaded with higher content of silicon, which has potential application value in improving the proton oxygen performance of PI.

Amino group-containing hyperbranched polysiloxane reacts with dianhydride to obtain a new type of polyimide material with hyperbranched polysiloxane structure in the main chain of the molecule, which realizes the modification of PI molecular level and effectively solves the problem of composite coating. The layer is brittle and difficult to handle. In the filling method, the filler is dispersed evenly. At the same time, by adjusting the degree of branching of the hyperbranched polysiloxane, a thin film material with excellent proton oxygen properties and comprehensive mechanical properties can be obtained through molecular weight and amino group content.

The atomic oxygen exposure experiment shows that the hbpsi polyimide film will produce an inert protective layer of SiO2 on the surface under the high temperature and high oxygen environment, thereby preventing the further etching of the substrate by atomic oxygen, making the material exhibit "self-healing" or "self-healing" self-healing ability. The large ellipsoid structure of hyperbranched polysiloxane has obvious steric hindrance, which can increase the molecular chain spacing and the free volume of the polymer, thereby effectively preventing the transfer of heat and charges.

Therefore, the introduction of the hyperbranched structure not only inhibits the formation of charge transfer complexes, but also endows PI with good heat resistance and optical properties, thus providing a powerful opportunity for the wide application of hbpsi polyimide films in the aerospace field. support!

There are various classification methods for die-cut polyimide film special engineering plastics. This article only discusses the polyimide used as engineering plastics, which is classified and explained according to the physical structure characteristics and chemical structure characteristics.

According to its physical properties, it can be divided into crystalline and amorphous. Most polyimides are amorphous, and only a few are crystalline and semi-crystalline.

Crystalline polyimides have distinct melting points, relatively low melt viscosity, and are processable above the melting point. It is the preferred structure type for the development of thermoplastic polyimides. Amorphous polyimides are often molded because they have no melting point and still have a high melt viscosity above the glass transition temperature (TG).