A novel process was developed to prepare electrically conducting maleic anhydride grafted polypropylene (gPP)/expanded graphite (EG) nanocomposites by solution intercalation. The conducting percolation threshold at room temperature (⌽ c ) of the nanocomposites was 0.67 vol %, much lower than that of the conventional conducting composites prepared by melt mixing (⌽ c ϭ 2.96 vol %). When the EG content was 3.90 vol %, the electrical conductivity () of the former reached 2.49 ϫ 10 Ϫ3 S/cm, whereas the of the latter was only 6.85 ϫ 10 Ϫ9 S/cm. The TEM, SEM, and optical microscopy observations confirmed that the significant decrease of ⌽ c and the striking increase of might be attributable to the formation of an EG/gPP conducting multiple network in the nanocomposites, involving the network composed of particles with a large surface-tovolume ratio and several hundred micrometers in size, and the networks composed of the boards or sheets of graphite with high width-to-thickness ratio and particles of fine microscale or nanoscale sizes.
CoSe2 materials with different nanostructures are used as pseudocapacitive Mg-storage cathodes, which exhibit fast solid-state Mg2+ ions diffusion kinetics.
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 () 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 ( or f w ), and g-PE weight contents (C g ) on the structure and of the nanocomposites, as compared to PE/g-PE/EG composites and PE/EG control produced by direct melt mixing (DMM). The percolation thresholds ( c ) of the SI, MMM, and DMM composites (C g /f w ϭ 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 of the MMM and DMM composites with f w ϭ 9% rises from the order of 10 Ϫ16 to 10 Ϫ4 and 10 Ϫ8 S/cm, respectively. These were closely associated with the morphology and microstructure of the composites varying with the preparation methods ( and C g /f w ) and could also be interpreted in terms of percolation theory.
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