Preparation Polyimide/Multi-walled Carbon Nanotubes Films Ternary Hybrid Films

Polyimide is akind of high temperature resistant organic polymere film, is widely used in navigation, aviation, space shuttle, electronic electric appliance industry, and other fields. In recent years, scholars use inorganic nanometer materials to modified polymide for meeting higher request of polyimide film in the various areas. Because MWNT (Multi-walled carbon nano-tubes) have unique structure, the great length-diameter ratio and good electrical conductivity, etc. which are different from other inorganic nano-particles, they become the favors of domestic and foreign scholars, and an ideal material for polyimide modification. But MWNTs were very easy to reunite for the carbon nano-tubes has very high specific surface area and surface activation energy, so it lead MWNTs dispersed no-effectively to the polymer matrix, and that limit the application of carbon nano-tubes. Therefore, to make the carbon nanotubes dispersed evenly in polymer matrix, the effective functional treatment of carbon nano-tubes is very important to scholars, and it becomes the hot spot.This paper use the mixed acid which consists with strong sulfuric acid and nitric acid to treat multi-walled carbon nanotubes, and the acidificatied multi-walled carbon nanotubes are doped to polyamide acid matrix which is prepared by the method of situ polymerization by mechanical agitation. And then the PI/MWNTs ternary hybrid films were gained through the thermal imine process. The morphology characterization of the surface and sections of the ternary hybrid films which contains acidize carbon nanotubes were analysised by scanning electron microscope (SEM); The results show that, carbon nanotubes are effectively dispersed evenly in distilled water and ethanol reagents after acidification treatment and no apparent reunion phenomenon, the compatibility in polyimide matrix was improved too. Ternary hybrid film has better thermal stability than pure polyimide film. With the content of carbon nano-tubes increasing, the thermal decomposition temperature of ternary hybrid films increased. The tensile strength of ternary hybrid films were first rised and then reduced with the content of carbon nano-tubes increasing, at the meanwhile, the elongation at break declined roughly. When the content of MWNTs is1.22wt%, the maximum tensile strength of ternary hybrid film is129.8Mpa, which increased by25.5%and11.1%respectively than pure film and the monolayer hybrid film; but at this time, the elongation at break was reduced by55%than pure film, but that was increased by11.3%than monolayer hybrid film. Ternary hybrid film didn’t play a toughening effect compared to the pure film, but it played some toughening effect compared to the monolayer hybrid film.