PREPARATION, STRUCTURE AND ELECTRICAL CONDUCTIVITYOF POLYETHYLENE/ GRAPHITE NANOCOMPOSITES

Polyethylene ( PE ) / maleic anhydride grafted polyethylene ( gPE ) / expanded graphite ( EG) electricallyconductive nanocomposites were prepared by solution intercalation (SI ) and masterbatch melt mixing (MMM ) methods.The electrical conductivity (σ) measurement , TEM , SEM and OM observations as well as DSC analysis were used to examine the influences of preparation methods , EG volume or mass fractions ( ? or f_m ) and gPE mass contents ( C_g ) onstructure and σof the nanocomposites , as compared with PE/ gPE/ EG composites and PE/ EG control materials preparedby direct melt mixing (DMM ) method. The percolation thresholds ( ?_c )of the SI- , MMM- , DMM-composites with C_g/ f_m = 115 and the DMM-PE/ EG controls were determined to be 2.19 % , 3.81 % , 4.68 % and 5.35 % , respectively. Asthe C_g/ f_m increased from 1 to 4 , theσof the MMM- , DMM-composites with f_m = 9 % rose by 12 and 8 orders of magnitude , respectively. These were closely associated with the morphology and internal microstructure of EG dispersed phasein the composites varying with preparation methods , ? and C_g/ f_m , and could be interpreted in terms of percolation theory.