Polymer positive temperature coefficient(PTC) material comprising conductive particles, e.g. carbon black(CB), dispersed in polymer matrix is suitable for use as electrical devices such as circuit overcurrent protecti...Polymer positive temperature coefficient(PTC) material comprising conductive particles, e.g. carbon black(CB), dispersed in polymer matrix is suitable for use as electrical devices such as circuit overcurrent protection device, self-regulation heaters, sensors, etc.. In this paper, the PTC effect of carbon black filled polyethylene and ethylene-propylene-diene terpolymer blends was studied. Effects of raw material ratio and type of carbon black were investigated. The distribution of CB in polymer matrix and the function of crystallites on PTC effect were discussed.展开更多
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 CF t...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 CF to 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 PTC intensity and PTC transition temperature are achieved for the radiated LDPE/CF composites.展开更多
文摘Polymer positive temperature coefficient(PTC) material comprising conductive particles, e.g. carbon black(CB), dispersed in polymer matrix is suitable for use as electrical devices such as circuit overcurrent protection device, self-regulation heaters, sensors, etc.. In this paper, the PTC effect of carbon black filled polyethylene and ethylene-propylene-diene terpolymer blends was studied. Effects of raw material ratio and type of carbon black were investigated. The distribution of CB in polymer matrix and the function of crystallites on PTC effect were discussed.
文摘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 CF to 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 PTC intensity and PTC transition temperature are achieved for the radiated LDPE/CF composites.
