| The addition of nucleating agent was to reduce the nucleation activation energy needed for heterogeneous nucleation, and then to optimize the cell structure. The graphene nanocomposites had become a research hotspot in recent years, owning to their superior electrical properties, mechanical properties and thermodynamic properties. The microcellular graphene nanocomposite foam has smaller cell size than pure polymer foam does, and thus exhibits higher cell density and more uniform distribution of cell size, which leads to more excellent material performance.In this study, the styrene maleic anhydride copolymer (SMA) as compatilizer and graphene as filler were added into the polystyrene (PS) substrate to prepare polystyrene/SMA/graphene nanocomposites microcellular foam. The foaming process, the addition of graphene and SMA influence the cell morphology, including cell size, cell density and the distribution of cell size. By deeply discussed the relationship between cell morphology and foaming technological parameters, the experimental process was optimized. then, the interaction between polymers and supercritical fluid, the phase transition and rheological characteristics of materials during cell growth process were studied. Three different kinds of SMA were selected to prepare PS/SMA/graphene nanocomposites for investigating the influence of SMA on electrical conductivity and electromagnetic shielding performance.The result indicated that the presence of graphene as well as SMA provide heterogeneous nucleation effect, greatly reduce cell size and improve cell density. The electrical conductivity were closely related to the density of the bulk material. The addition of SMA has greatly increased not only the electrical conductivity but also the electromagnetic interference (EMI) of the foamed graphene nanocomposites. With graphene content of5.0wt%, EMI efficiency of the composites can reach to22dB, which met the requirements of low electromagnetic shielding materials. |
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