Abstract: In this paper, carbon fiber(CF)-filled low density polyethylene(LDPE)composite materials were prepared by conventional melt-mixing method.Wide angle X-ray diffraction(WAXD) observation shows that the addition of CFto LDPE does not influence the aggregate structure of the polymer.The change of the resistivity with increasing temperature is determined by two following factors: one is the expansion of the polymer which makes resistivity rise and leads to a positive temperature coefficient(PTC) effect; the other is the agglomeration of filler particles which makes resistivity drop and leads to a negative temperature coefficient(NTC) phenomenon.It is found that the crosslinking under γ-ray radiation can effectively eliminate the NTC phenomenon by forming a network and reducing movement of the CF.And a higher PTCintensity and PTC transition temperature are achieved for the radiated LDPE/CF composites.

Key words: Low density polyethylene, Carbon fiber, Positive temperature coefficient, Negative temperature coefficient, Radiation crosslinking