Preparation And Electrically Conductive Properties Of Graphene/Polystyrene Nanocomposites

Graphene, two-dimensional layers of sp2 bonded carbon, become a hot topic in recent years. It was reported that graphene is equipped with excellent mechanical, thermal, optical and electrical performance owing to its unique two-dimensional structure.Comparing to carbon nanotubes, graphene has a greater surface area, which makes it more superior in many ways. The researchers found that the velocity of electron reaches the speed of light 1/300 in graphene, far more than the normal conductor. Graphene can be widely used in conductive composites because of its excellent conductivity.In the past years, the conductive nanocomposites had been limited in application due to the high content of fillers, resulting in the reduction in their mechanical properties. Here, graphene was prepared by Schniepp method. We prepared graphene/PS conductive nanocomposites by solution method. The results showed that the ideal conductivity was reached by adding low levels of graphene. The main work is as follows: 1. Graphene were prepared by Schniepp method, the X-ray shows that the interlayer spacing of graphite expanded from 0.34nm to 0.71nm after oxidation.Then, we confirm that graphite oxide(GO) contains a large number of active functional groups (-COOH,-OH, etc) by IR and XPS. After thermal reduction, graphene was completely exfoliated, which was observed by XRD and TEM. And the thickness of graphene is nearly 0.34 nm.2. We prepared carbon nanotubes/PS and graphene/PS nanocomposites by solution method, and compared their electrical conductivity. It is found that the conductivity of graphene is superior than carbon nanotubes. Observed from the TEM and SEM microphotographs, graphene nanosheets were homogeneously dispersed in PS matrix, while there existed some agglomerations in CNT/PS. And the graphene sheets were exfoliated completely3. We prepared graphene oxide/polystyrene nanocomposites by solution method. Then, they were dried at 120℃in a vacuum oven for 12 hours. The result shows that the thermal reduction of graphite oxide occurred, which is certified by TGA.4. We prepared graphene/polylactic acid/polystyrene and the graphene/ CaCO3/polystyrene conductive nanocomposites. Compared to graphene/ polystyrene, either adding PLA or CaCO3, the conductivity increased a lot. Observed from the TEM and SEM microphotographs, the third phase plays a role of Volume exclusion, which increased the content of graphene practically. The effect of CaCO3 is not as good as PLA due to its nano size. In that case, the agglomerations of CaCO3 reduce the volume exclusion effect.