Graphite nanosheets (GNs) modified with sodium dodecyl benzene sulfonate (SDBS) was prepared and then incorporated into high-density polyethylene The GNs/HDPE nanocomposites displayed pronounced enhancements of the mechanical properties. With a load of 10 wt % of the modified GNs, the nanocomposites exhibited all increase of about 290% in the elongation at break as well as all increase of about 14% in the elastic modulus in comparison with neat HDPE. Scanning electron microscopy (SEM) shows a notable microscopic orientation of the matrix and GNs in the strained nanocomposite specimen, which may play an important role in the dramatic increase in the elongation at break. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 116: 2029-2034, 2010