| Systematic investigation of positive temperature coefficients （PTC） effect of carbon black （Cb）/high density polyethylene （PE）, nickel plated carbon black （Cbp）/PE, functionalized carbon nanotube （Ctf）/PE composite specimens are reported in this study. Nickel coated on carbon particles by electroless plating, the Ctf were prepared by grafting maleic anhydride grafted polyethylene （PE-gMAH） molecules onto the modified carbon nanotubes （Ctm）. The volume resistivity values of the PEZ/Cbxy composite specimens are significantly reduced as the Cb contents increased at room temperature, and show obvious PTC effect. Especially, the volume resistivity values （≤102Ω.cm） and PTC effect intensity （≥5） of the PEZ/Cbxy composite specimens are accord to the requirements of no-fuse switch as the Cb contents values are equal to or greater than 25 wt%. Meanwhile, the volume resistivity values and PTC effect intensity of the PEZ/Cbxy composite specimens are increased as the diameters of Cb particle increased. The volume resistivity values of PE75/Cbap-25 composite specimens are always lower than those of the corresponding PE75/Cba25 composite specimens, and reduced as the nickel contents of Cbp increased. The volume resistivity values of PE75/Cbap23/Ctf-2 composite specimens are always lower than those of the corresponding PE75/Cbap25 composite specimens. In fact, the volume resistivity values of PE75/Cbap-23/Ctf-2 composite specimens are further found to reach a minimum values as their weight ratios of PE-g-MAH to modified CNTs approach an optimum value at 1. In order to understand the above interesting phenomenon, fourier transform infra-red （FT-IR） spectra, surface morphologies, specific surface areas and x-ray fluorescence （XRF） spectrometry of Cb, Cbp, Ct, Ctf specimens, transversal section morphologies and PTC effect of the PE/Cb, PE/Cbp, PE/Cbp/Ctf specimens are performed in this study. |
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