基于交流阻抗的聚乙烯/碳纳米管导电复合材料的室温逾渗性能

Electrical Percolation of HDPE/CNTs Composites in Terms of AC Impedance at Room Temperature

聚合物基导电复合材料的室温逾渗机理是其使用和制备的重要基础。为了阐述聚乙烯/碳纳米管导电复合材料的室温逾渗性能,文中基于交流阻抗的分析思路和方法,采用电阻电容的等效电路模拟复合材料中的电学性能。以熔融法制备的高密度聚乙烯(HDPE)/碳纳米管(CNTs)复合材料为研究对象,测试其室温下的电学性能与CNTs含量间的关系,其中交流(AC)阻抗测试频率范围为100Hz到106.5Hz。当碳纳米管质量分数为0.5%时复合材料的电导率升至10^(-6)S/cm,表明复合材料中逾渗网络已初步形成。随频率变化的AC阻抗可清晰地展示HDPE/CNTs中导电网络的形成过程,并表明在导电复合材料的电学逾渗中,复合材料的导电机理逐渐由电容主导向电阻主导变化。

The electrical percolation mechanism is the fundamental for polymer based conductive composites. In order to explain the electrical percolation behavior, the AC impedance and equivalent circuit were used to discuss electrical properties of polyethylene/carbon nanotubes （PE/CNTs） composites at room temperature. Composites of CNTs filled with high density polyethylene （HDPE） matrix were prepared by kneading method and their electrical properties against CNTs content were investigated by direct current （DC） and alternating current （AC） measurements over the frequency range of 10~ Hz to 106. 5 Hz. The electrical conductivity increases to 10-6 S/cm with the CNTs mass fraction of 0.5 % which means formation of CNTs conductive networks. The frequency dependent of AC impedance could clearly show primary formation of the conductive network and transition of the insulator- conductor. Based on the results, the conductive mechanism changes from capacitance to resistance during the percolation process.