The microstructure and property study of tri-layer polyimide/Al<SUB align="right">2O<SUB align="right">3 nanocomposite films

Abstract

On the basis of mono-layer composite films, the polyimide/nano-Al2O3 tri-layer composite films based on pyromellitic dianhydride (PMDA) and 4,4'-oxydianiline (ODA) were prepared by mixing various proportions of nano-Al2O3 inorganic particles via in situ polymerisation. Morphology study by scanning electron microscope (SEM) illustrated that the 'sandwich' structure was successfully achieved and nano-Al2O3 particles were homogeneously dispersed in the PI matrix. The target tri-layer composite films were studied by thermogravimetry analysis (TGA), and corresponding experimental results showed that same as the mono-layer composite films, tri-layer composite films possessed the superior thermal stability than that of pure film, and the thermal stability was improved steadily along with the increment of nano-Al2O3 doping content. Moreover, comparing to the mono-layer composite films, tri-layer PI/Al2O3 nanocomposite films had a great deal of improvement in the tensile strength and elongation at break. The tri-layer PI/Al2O3 nanocomposite films performed the better electric breakdown strength than that of pure films.