In order to improve the thermal stability and mechanical behavior of polyimide

a series of polyimide/silica composite films with different silica content up to 45 wt% were successfully prepared by sol gel reaction of tetraethoxysiliane in the presence of polyamic acid

a precursor of polyimide. The films with silica content less than 10 wt% were yellow and transparent

whereas the films with silica content higher than 10 wt% were yellow and opaque. The structure and physical properties were studied by FT-IR

TGA

DMA

TEC

stress-strain analysis and SEM. The results indicated that these polyimide/silica composite materials were nanocomposite materials.The density

decomposition temperature and modulus increased with increasing silica content

and the linear thermal expansion coefficient of the silica in the composite films decreased

whereas tensile strength and elongation at break have maxium with the change of silicate content.