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Microstructure and viscoelastic behaviors of graphene/PMMA nanocomposites

The microstructure and viscoelastic behaviors of graphene filled poly(methyl methacrylate) nanocomposites (graphene/PMMA) have been investigated. The composites were prepared by in situ polymerization method with graphene weight fraction from 0.1 to 1 wt.%. The microstructures were observed by transmitted polarization microscope (TPM) and scanning electron microscope (SEM). The viscoelastic behaviors characterized by storage modulus and loss tangent were measured by dynamic nanoindentation method. The effects of graphene content and force frequency on the viscoelastic behaviors were studied and discussed according to the features of microstructures and mobility of molecular chains. The graphene nanosheets with an average diameter of about 8.6 micrometers are found to disperse homogeneously in the PMMA matrix. The interface between graphene and PMMA is strong and few defects are observed in the impact fracture surfaces of the composites. The results indicate that the microstructure and viscoelastic properties of PMMA polymer are significantly improved by adding a low content of graphene.