Graphene sheets were carbon materials with high surface area, and excellent electrical properties. One of the most
promising applications of those materials is in polymer nanocomposites. Their multifunctional properties may create new
applications of polymer nanocomposites. In this paper, graphene sheets were prepared by oxidation-reduction method.
The graphite was oxidized by potassium permanganate and sulphuric acid. The graphene oxide nanosheets, which were
exfoliated from graphite oxide by ultrasound in water, were reduced by hydrazine hydrate, and the graphene nanosheets
were obtained. Thereafter, the graphene sheets were dispersed in N,N-dimethylacetamide by simple sonication treatment.
The graphene sheets/polyimide nanocomposites were synthesized by in situ polymerization using
N,N'-dimethylformamide, graphene sheets and pyromellitic dianhydride. It was observed from transmission electron
microscopy of graphene oxide sheets and graphene sheets that the very thin sheets were obtained by exfoliation of
graphite. The result of FT-IR spectral analysis for graphene sheets shows the functional groups on the graphene sheets
surface were almost the same as graphite, and that means the graphene sheets were complete reduced by hydrazine
hydrate. A homogeneous dispersion of graphene sheets was achieved in polyimide as evidenced by scanning electron