Polyimide nano-coating on carbon fibers by electrophoretic deposition

An anti-oxidative polyimide nano-coating on carbon fibers was obtained by electrophoretic deposition of polyamic acid nano-emulsion. The polyamic acid nano-emulsion was synthesized using pyromellitic dianhydride and 4,4-oxydianiline in N,N-dimethylacetamide solution. The polyamic acid nano-emulsion with an average particle size of 320 nm was electrophoretic deposition on carbon fibers and transferred into polyimide after imidization at 280 °C. The properties of polyimide-coated carbon fibers were characterized using field-emission scanning electron microscope, X-ray photoelectron spectroscopy, Fourier transforms infrared spectroscopy and thermogravimetric analysis. The results showed that a continuous and uniform polyimide nano-coating of 80–100 nm was formed on carbon fibers. The polyimide-coated carbon fibers displayed an excellent thermal stability up to 500 °C in air.