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Epoxy/graphene nanocomposites

Associate Professor Jun Ma, Associate Professor, University of South Australia

Abstract

Professor Jun Ma’s research team since 2008 has conducted extensive research of developing new graphene platelets and using them for processing of epoxy and elastomers. Graphene platelets contain only 7 atom% oxygen and each may have a thickness of 2–4 nm in average. They have electrical conductivity of 1456 S/cm measured by a four-probe method. The selection of hardeners is vital for epoxy/unmodified graphene composites. They compared two groups of composites respectively cured by polyoxypropylene and 4,4′-diaminodiphenylsulfone (DDS). The DDS-cured composites showed better dispersion and exfoliation, a higher improvement 573.0% in fracture energy release rate and a lower percolation threshold 0.612 vol% for electrical conductivity, because DDS containing benzene groups created π-π interactions with graphene promoting dispersion and exfoliation during curing. In a further research, we used DDS to chemically modify graphene platelets, covalently bonded the platelets with an epoxy matrix, and investigated the morphology and functional and mechanical performance of these composites. The covalently bonded interface prevented graphene platelets stacking in the matrix. In comparison with the unmodified composites, the interface-modified composite at 0.489 vol% graphene demonstrated an eight-order reduction in the resistivity, a 47.7% further improvement in modulus and 84.6% in fracture energy release rate.

Bio

Jun Ma received his Ph.D. degree in Polymer Physics and Chemistry from Beijing Institute of Chemistry, Chinese Academy of Sciences in 2002, and he is an Associate Professor in the School of Engineering, University of South Australia. He has published over 100 journal papers, with a Google H-index of 39. His current interests include functional composites and polymer processing. Emphasis is on the development of cost-effective processing methods for nanomaterials and the effect of these materials on the mechanical and functional properties of their polymer composites as well as various mechanisms behind high performance.