Polyethylene/grafted polyethylene/graphite nanocomposites: Preparation, structure, and electrical properties

Polyethylene (PE)/maleic anhydride grafted PE (g-PE)/expanded graphite (EG) electrically conductive nanocomposites were successfully prepared by solution intercalation (SI) and masterbatch melt mixing (MMM). Electrical conductivity (σ) measurements; transmission electron, scanning electron, and optical miscroscopy observations; and differential scanning calorimetry analyses were employed to examine the influences of the preparation methods, EG volume or weight fractions (Φ or fw), and g-PE weight contents (C g) on the structure and σ of the nanocomposites, as compared to PE/g-PE/EG composites and PE/EG control produced by direct melt mixing (DMM). The percolation thresholds (Φc) of the SI, MMM, and DMM com posites (Cgfw = 1.5) and the DMM control were measured and found to be 2.19, 3.81, 4.68, and 5.35%, respectively. As the C g/fw increases from 1 to 4, the σ of the MMM and DMM composites with fw = 9% rises from the order of 10-16 to 10-4 and 10-8 S/cm, respectively. These were closely associated with the morphology and microstructure of the composites varying with the preparation methods (Φ and Cgfw) and could also be interpreted in terms of percolation theory. © 2005 Wiley Periodicals, Inc.