Modification of polyimide

Blending modification

Blending modification is a common method of polymer modification, and it has also been applied in the modification of polyimide. Polyimide can be blended with other organic or inorganic materials to combine the excellent properties of different materials, so that it has some new functions. The commonly used blend modifiers are epoxy resin (EP), thermoplastic polyurethane (TPUR), polytetrafluoroethylene (PTFE), polyether ether ketone (PEEK), etc.

(1) PI and PTFE were blended. Huang Li et al. used polytetrafluoroethylene as the friction reducing and toughening material of thermosetting polyimide, and prepared the blends by four methods, namely, simple mechanical blending, solution blending, colloid mill blending and air jet milling blending. The changes of particle size of polytetrafluoroethylene in the process of blending, and the effects on the friction and wear properties and microstructure of the blends were studied and discussed. The results showed that the particle size of PTFE was smaller and the impact strength of the blends was improved in the air jet comminution blending process; At the same time, the decrease of PTFE particle size and the increase of PTFE quantity are conducive to the transfer to the friction surface, shortening the time for the material to reach the friction dynamic equilibrium, thus improving the friction and wear performance of the blend material.

(2) PI and EP were blended. Epoxy resin has excellent adhesion, good thermal and mechanical properties. Blending it with polyimide can improve the heat resistance, bonding strength and shear strength of the modified product. For example, polyamic acid (PAA), an intermediate of condensed polyimide, is blended with epoxy resin to obtain an adhesive with excellent performance. This blend not only maintains the high heat resistance of polyimide, but also improves the adhesion of polyimide.

(3) Blending modification of PI and PEEK. Lai Yumei et al. Modified polyimide by mechanical blending and polyetheretherketone as modifier to prepare thermoplastic polyimide / polyetheretherketone (TPI / PEEK) blend. The results show that the crystallization temperature and melting point of the prepared blend are related to the content of the filler. With the decrease of 1H content, the crystallization temperature and melting point of the blend increase. Compared with the unmodified filler, its mechanical properties at high temperature are improved, and the processing properties of the material are also improved.