Mechanical properties of compound modification carbon fiber reinforced thermoplastic polyimide

To improve the mechanical properties of the short cut carbon fiber reinforced thermoplastic polyimide composites (CF/TPI)，the compound modification method of nitric acid oxidation and polyimide coating was adopted to modify the CF. The t reated and untreated CF were characterized by BET，AFM，SEM and TGA. The results show that the specific surface area of CF increases 144.2% after nitric acid oxidation，by increasing the roughness of CF. A PI layer is coated on the CF，and the CF thermal stability increases after coating PI. The tensile strength，elastic modulus，flexural strength and impact strength of the CF/TPI composites are improved by 11.34%，109.2%，18.78% and 74.15% respectively after compound modification of the carbon fiber.