Material properties Functionalized-graphene/ethylene vinyl acetate co-polymer composites for improved mechanical and thermal properties Tapas Kuila a , Partha Khanra a , Anata Kumar Mishra b , Nam Hoon Kim c , Joong Hee Lee a, b, c, * a WCU Programme, Department of BIN FusionTechnology, Chonbuk National University, Jeonju, Jeonbuk 561-756, Republic of Korea b BIN Fusion Research Team, Department of Polymer & Nano Engineering, Chonbuk National University, Jeonju, Jeonbuk 561-756, Republic of Korea c Department of Hydrogen and Fuel Cell Engineering, Chonbuk National University, Jeonju, Jeonbuk 561-756, Republic of Korea article info Article history: Received 27 October 2011 Accepted 8 December 2011 Keywords: Graphene Ethylene vinyl acetate Nanocomposites Mechanical properties Thermogravimetric analysis abstract The surface functionalization of graphene and the preparation of functionalized graphene/ ethylene vinyl acetate co-polymer (EVA) composites by solution mixing are described. Octadecyl amine (ODA) was selected as a surface modifier for the preparation of func- tionalized graphene (ODA-G) in an aqueous medium. The ODA-G was characterized by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy, which confirm the modification and reduction of graphite oxide to graphene. Atomic force microscopy shows that the average thickness of ODA-G is ca. 1.9 nm. The ODA-G/EVA composites were characterized by X-ray diffraction and transmission electron micros- copy, which confirms the formation of ODA-G/EVA composites. Measurement of tensile properties shows that the tensile strength of the composites (with 1 wt.% ODA-G loading) is w74% higher as compared to pure EVA. Dynamic mechanical analysis shows that the storage modulus of the composites is much higher than that of pure EVA. The thermal stability of the composite with 8 wt.% of ODA-G is w42  C higher than that of pure EVA. The electrical resistivity has also decreased in the composites with 8 wt.% of ODA-G. Ó 2011 Elsevier Ltd. All rights reserved. 1. Introduction Graphene has attracted considerable research interest in physics, chemistry, bio-science and materials science [1–4]. Its unique features, such as its excellent electrical conduc- tivity, mechanical flexibility, thermal conductivity and optical transparency, give it practical applicability and make it theoretically interesting [5–8]. It has been widely used as a nanofiller in the preparation of polymer composite mate- rials [9–14]. The percolation in mechanical, and electrical properties of the polymer composites can be achieved by using graphene at lower content than required for other carbon-based nanofillers because of its large surface area and good electrical conductivity [9–14]. However, the preparation of homogeneous graphene-polymer composites entails some difficulties [13]. First, polymer composites require the volume production of nanofiller for industrial application. Second, pristine graphene does not disperse well in polymers and has a tendency to form phase sepa- rated composites [10,14]. Strategies to overcome these shortcomings are outlined below. Graphene can be produced by several methods: micro- mechanical cleavage of natural graphite, chemical vapor deposition (CVD), plasma enhanced CVD, electric arc discharge, epitaxial growth on electrically insulating surfaces such as SiC, unzipping of carbon nanotubes and the solution-based reduction of graphite oxide [15–18]. Among these, the last method shows potential for the production of graphene sheets in the bulk quantities required for polymer composites preparation. The compatibility of graphene with polymers can be increased through appropriate surface * Corresponding author. Department of BIN Fusion Technology, Chonbuk National University, Jeonju, Jeonbuk 561-756, Republic of Korea. Tel.: þ82 63 270 2342; fax: þ82 63 270 2341. E-mail address: jhl@chonbuk.ac.kr (J.H. Lee). Contents lists available at SciVerse ScienceDirect Polymer Testing journal homepage: www.elsevier.com/locate/polytest 0142-9418/$ – see front matter Ó 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.polymertesting.2011.12.003 Polymer Testing 31 (2012) 282–289