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聚乙烯—炭黑导电复合材料的电流—电压特性
On the Current--Voltage Characteristics of Polyethylene--Carbon Black Conductive Composites
【摘要】 本文研究了炭黑含量为10.6—12.2Vol%的聚乙烯—炭黑导电复合材料的直流I—U特性。按测试电压可分为Ohm区及非Ohm区。电流及电阻和电压的关系可分别用公式I=AUB和R=A-1U1-B表示,式中A、B为常数,分别表征导电能力和导电的性质。在非Ohm区,B>1,电阻随电压增加而下降。炭黑含量减少或升高温度都使常数B变大、A变小,由于聚乙烯和炭黑的膨胀系数相差很大,升温可看作减少炭黑浓度。热处理使B变小、A变大,这可能是炭黑粒子的运动使导电网络中非Ohm导电的成分减少的缘故,这种变化的不可逆性表明上述炭黑的运动是单方向的,它使导电网络趋于稳定,也使测量的稳定性和重现性有较大的改进。
【Abstract】 In order to obtain the proper electric properties of PTC material, testing the threshold cur- rent at constant voltage is essential if the voltage used is not low enough to avoid the influence of Joule heat. It was found that thc I-U characteristics of PE--CB composites which contain CB 10.6—12.2 Vol% can be divided into two regions, ohmic and nonohmic, according to the test voltage. The I—U and R—U behavior of the composites can be expressed by equations I = AUB and R = A-1UI-B in which constants A and B reflect the electric conduc- tivity and the nature of electron tranport respectivitely. Ih the nonohmic area, B > 1 and the re- sistance decreases as voltage increases. Because of the great difference between the thermoexpansion of PE and CB, increasing temperature enhances the values of A-1 and B, the same effect as reducing CB content. As a result of heat treatment, values of A-1 and B decrease. Probably, heat treatment, by stimulating the irreversible movement of carbon particles, com- pletes and stabilizes the conductive ntwork in the composites, so that the nonohmic component of conductances was decreased whild the ohmic component was inereased.
- 【文献出处】 Chinese Journal of Chemical Physics ,化学物理学报(英文版) , 编辑部邮箱 ,1989年02期
- 【被引频次】7
- 【下载频次】60