Functionalized reduced graphene oxide (RGO) was synthesized by modification of graphene oxide (GO) with octadecylamine (ODA), dodecylamine (DDA) and octylamine (OTA) and subsequent reduced by hydrazine hydrate. The successful grafting of alkylamine onto the RGO surface was confirmed by Fourier-transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA), and the structure of alkylamine-functionalized graphene was characterized by means of XRD and Raman spectroscopy. UV-vis spectra showed that RGO-DDA and RGO-ODA are of equivalent solubility in organic solvents. For the potential application of the alkylamine functionalized-graphene on polyolefin matrix, the properties of functionalized-graphene/low density polyethylene (LDPE) nanocomposites were evaluated in this paper. Initial results showed that RGO-DDA/LDPE nanocomposites exhibited higher mechanical properties and thermal stability at the same content of alkylated graphene compared with the RGO-ODA/LDPE nanocomposites. Our work provides a new horizon to choose a compatilizer with appropriate alkyl chain lengths in the development of graphene/polyolefin nanocomposites. (C) 2014 Elsevier B.V. All rights reserved.