Preparation And Carbonation Of SiC Reinforced Polyimide Composite Films

Firstly, polyimide films were prepared by two-step method, and SiC/PI nanocomposite films were prepared by solution blending method. The chemical structures and morphology of the nanocomposite films were characterized by FTIR、XRD、SEM、TEM, respectively. The results pointed to the successful incorporation of the SiC nano-particles within the polyimide matrix, and SiC nanoparticles happened in the different degree of reunion phenomenon with increasing content of SiC. The thermogravimetric analysis of the nanocomposites showded that improved thermal stability in comparison to the neat polyimide. The mechanics performance analysis of the films showed the tensile strength and elastic modulus of the composite films increased with the content of SiC. But when SiC content exceeds2.5%, the mechanical properties decreased with increasing SiC content, which is because the reunion phenomenon of nanoparticles affected the improvement of its mechanical properties. The fracture morphology of the composite films suggested that the fracture had obvious ductile fracture characteristics.In order to improve the dispersibility of the nanoparticles in the polyimide matrix, SiC was modified by y-aminopropyl trimethoxysilane(A-1110), and the modified SiC/PI composite films were prepared. Comparative analysis of the internal structure and properties between the Unmodified composite films and modified composite films is carried out.Through the FTIR spectra and Zeta potential tests of the SiC nanoparticles, we found that the surface of SiC had obvious traces of amino modification and the stability of solution had been significantly improved.The test result of properties showed that the thermal stability and mechanical properties of the modified composite films had significantly improved, which indicated that the modification of SiC nanoparticles had a great impact on the performance of the composite films.The modified SiC/PI composite films were carbonized in different temperatures. The FTIR spectra、XRD and EDX spectroscopy analysis was used to study the variation of the carbonized films’ internal structure in the carbonization process.The results showed that the structure and composition of the films had changed a lot with increased temperatures, and the graphite structure was gradually formed. Finally the study of the catalytic graphitization of the carbonized films of the different contents of SiC was carried out by means of SEM、XRD and other test methods, the test results indicated that SiC nanoparticles played a induced catalytic role in whole carbonization process.