Preparation of polystyrene/graphene oxide composites and their supercritical carbon dioxide foaming

We investigated the nucleation effect of well exfoliated and dispersed graphene oxide(GO) sheets on polystyrene(PS) supercritical carbon dioxide foaming. To get PS/GO composites with well exfoliated GO sheets, a method based on latex concept was employed. The characterizations based on X-ray diffraction and transmission electron microscope demonstrated the full exfoliation and uniform dispersion of GO sheets in polymer matrix. Thermal stability and dynamic mechanical properties of the compound materials were investigated by a series of measurements such as differential scanning calorimetry analysis, dynamic mechanical analysis and thermogravimetry analysis, which suggested the higher thermal stability and glass transition temperature of the composites. The supercritical carbon dioxide foaming of pure PS and composites was carried out in a batch foaming system, the results showed that the well exfoliated GO sheets could be a high efficient nucleation agent. For the pure PS foam and PS/GO composite foams produced under the foaming condition of 120 degrees C and 13.8 MPa, the average foam cell size was reduced from 7.1 um to 4.3 um and the cell density was increased from 4.52x10(9) to 1.84x10(10) cells/cm(3) by around 5.0 wt.% GO sheets.