Processable 3-nm thick graphene platelets of high electrical conductivity and their epoxy composites
Date
2014
Authors
Meng, Q.
Jin, J.
Wang, R.
Kuan, H.C.
Ma, J.
Kawashima, N.
Michelmore, A.
Zhu, S.
Wang, C.H.
Editors
Advisors
Journal Title
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Volume Title
Type:
Journal article
Citation
Nanotechnology, 125707th, 2014; 25(12, article no. 125707):1-13
Statement of Responsibility
Conference Name
Abstract
Graphene platelets (GnPs) are a class of novel 2D nanomaterials owing to their very small thickness (similar to 3 nm), high mechanical strength and electric conductivity (1460 S cm(-1)), and good compatibility with most polymers as well as cost-effectiveness. In this paper we present a low-cost processing technique for producing modified GnPs and an investigation of the electrical and mechanical properties of the resulting composites. After dispersing GnPs in solvent N-methyl-2-pyrrolidone, a long-chain surfactant (Jeffamine D 2000, denoted J2000) was added to covalently modify GnPs, yielding J2000-GnPs. By adjusting the ratio of GnPs to the solvent, the modified GnPs show different average thickness and thus electrical conductivity ranging from 694 to 1200 S cm(-1). To promote the exfoliation and dispersion of J2000-GnPs in a polymeric matrix, they were dispersed in the solvent again and further modified using diglycidyl ether of bisphenol A (DGEBA) producing m-GnPs, which were then compounded with an epoxy resin for the development of epoxy/m-GnP composites. A percolation threshold of electrical volume resistivity for the resulting composites was observed at 0.31 vol%. It was found that epoxy/m-GnP composites demonstrated far better mechanical properties than those of unmodified GnPs of the same volume fraction. For example, m-GnPs at 0.25 vol% increased the fracture energy release rate G(1c) from 0.204 +/- 0.03 to 1: 422 +/- 0: 24 kJ m(-2), while the same fraction of unmodified GnPs increased G(1c) to 1: 01 +/- 0: 24 kJ m(-2). The interface modification also enhanced the glass transition temperature of neat epoxy from 58.9 to 73.8 degrees C