Improvement of electric conductivity of LLDPE based nanocomposite by paraffin coating on exfoliated graphite nanoplatelets

Paraffin coated exfoliated graphite nanoplatelets (xGnP) reinforced with Linear Low-Density PolyEthylene (LLDPE) nanocomposites have been fabricated and characterized for mechanical, electrical and morphological properties. Paraffin was added to decrease the percolation threshold of electric conductivity. LLDPE-paraffin/xGnP nanocomposites were prepared by separate solution and total solution mixing methods. The mixture master batch of each mixing method was injection-molded to produce composites with a mini twin-screw extruder. The separate mixing method was not suitable since there was not enough electrical conductivity due to the low xGnP content in the nanocomposites. However, paraffin does not affect mechanical properties until around 30 wt% of content has been added, even though the content is low molecular weight polyethylene. When the total mixing method was used, the adding content of xGnP and paraffin was easily controlled. Five weight percentage of xGnP loaded nanocomposite showed electrical conductivity when 10 wt% of paraffin was added. From the results of SEM images of fracture surface and DSC, it could be seen that Paraffin was well coated on xGnP, resulting in a separate phase between xGnP and LLDPE. By coating paraffin on xGnP in the LLDPE matrix, the percolation threshold dramatically decreased compared to the xGnP-LLDPE nanocomposite. (C) 2009 Elsevier Ltd. All rights reserved.