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 (sigma) measurements; transmission electron, scanning electron, and optical miscroscopy observations; and differertial scanning calorimetry analyses were employed to examine the influences of the preparation methods, EG volume or weight fractions (phi or f(w)), and g-PE weight contents (C-g) on the structure and sigma of the nanocomoposites, as compared to PE/g-PE/EG composites and PE/EG control produced by direct melt mixing (DMM). The percolation thresholds (phi(c)) of the SI, MMM, and DMM composites (C-g/f(w) = 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/f(w) increases from 1 to 4, the sigma of the MMM and DMM composites with f(w) = 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 (phi and C-g/f(w)) and could also be interpreted in terms of percolation theory. (c) 2005 Wiley Periodicals, Inc.