A preparation process of PMMA/graphite nanocomposites was developed via in situ polymerization of monomers in the presence of sonicated expanded graphite with the aid of sonication.Expanded graphite was sonicated in a 70% aqueous alcohol solution to get graphite platelets (NanoG) with thickness of 30～80 nm and diameter of 0.5～20 μm.The NanoG were dispersed in MMA monomers with BPO initiator.In situ polymerization was taken place when the mixture was heated under sonication.The TEM studies showed that the graphite nano-platelets were well dispersed in the PMMA matrix.Solution cast films of the nanocomposite were used for electrical conductivity measurements.The percolation threshold of polymer/NanoG nanocomposite films at room temperature was lower than 1.0 wt%,which was much lower than that of the composites with conventional graphite filler which was 5.5 wt%.The electrical conductivity reached 10 -3 S/cm at a graphite content of about 4.0 wt%.The special structure of graphite nano- platelets with high aspect ratio of as high as 100～500 (width-to-thickness) played an important role in forming a conducting network within the PMMA matrix.
Expanded graphite,prepared from the rapid heating of graphite intercalated compound,was blended with polystyrene via the intercalation and the in situ polymerization of styrene.SEM,STM and etc were used to characterize the nanostructure of the expanded graphite the composite of polymer/expanded graphite,and the changes of the nanostructure during the rolling process.The graphite formed the nanostructure during the expanding process of the GIC.The nanosheets were confirmed to have been dispersed in polystyrene matrix with the thickness of 10～30 nm.The conductivity of PS/expanded graphite composite was sensitive to the rolling process.The intensive rolling caused great decrease in its conductivity,due to the destruction of conducting network.
