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 (Cg) 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 composites (Cg/fw = 1.5) and the DMM control were measured and found to be 2.19, 3.81, 4.68, and 5.35%, respectively. As the Cg/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 Cg/fw) and could also be interpreted in terms of percolation theory.