碳纳米管-聚乙烯复合材料的介电性能

Dielectric Properties of Carbon Nanotubes-Polyethylene Composites

采用熔融共混及模压的方法制备了碳纳米管（CNT）-高密度聚乙烯（HDPE）复合材料，并用介电谱仪研究了逾渗值附近的导电填料对复合材料体系在不同温度、频率条件下的介电常数、介电损耗、交流电阻率的变化规律。结果表明：复合材料的介电常数、介电损耗均随CNT质量分数增加而逐渐增大；在频率为10^3-10^6 Hz，温度为40-130℃时，HDPE基体的介电常数随频率和温度的变化较小，而添加CNT填料的复合材料的介电常数随频率和温度的增加而略微降低。当w（CNT）〈0.5%时，复合材料的交流电阻率表现出对频率的强烈依赖性；而当w（CNT）〉0.5%时，在低频处表现出直流特性，在高频处显示出交流电阻率的降低。

mHigh-density polyethylene （HDPE） composite films filled with different carbon nanotube （CNT） contents were prepared by melt mixing and molding.The dielectric propereties of the composite films were investigated at different temperatures and frequencies.Results show that the dielectric permittivity and the loss of composite strongly depend upon the filler content,frequency and temperature.The permittivity of pure HDPE is slightly dependent on frequency and temperature in a frequency range of 10^3-10^6 Hz and temperature range of 40-130℃,but the permittivity of composites decreases with the increasing of frequency and temperature.The alternating current （AC） resistivity of composites shows a strong dependence on frequency when the filler mass fraction is under 0.5%.While the filler mass fraction is more than 0.5%,the resistance varies with frequency changes,exhibiting direct current （DC） characteristics in the low frequency region,and AC resistivity decreases at high frequency.