研究了石墨填充丙烯腈-丁二烯-苯乙烯共聚物(ABS)复合材料的直流(DC)和交流(AC)导电特性和线性粘弹行为.电性能测试结果表明,石墨体积分数为13.21％～16.36％时,ABS/石墨复合材料的DC电阻率突降6个数量级,说明发生电学逾渗;同时,AC电阻率在低频区不随频率而变化,且AC阻抗复平面图中阻抗实部与阻抗虚部呈现半圆弧,进一步证明导电网络的形成.流变性能测试结果表明石墨体积分数为10.24％～13.21％时复合体系的储能模量和复数黏度出现跳跃,损耗因子(tanδ)的峰值减小且逐渐向高频移动,说明复合体系从“类液态”转变为“类固态”,发生流变逾渗现象.流变逾渗阈值小于导电逾渗阈值是因为传递电子时石墨之间的距离比阻碍聚合物分子链运动时石墨之间的距离小.
The direct current (DC) and alternating current (AC) electrical properties and linear viscoelastic behaviors of acrylonitrile-butadiene-styrene copolymer filled with graphite were investigated.The results show that the DC resistivity of ABS/graphite composites decreases about 6 orders of magnitude when the graphite volume fraction is 13.21％～ 16.36％,meaning the occurrence of electrical percolation.Meanwhile,the AC electrical resistivity is independent of frequency at lower frequency and AC impedance complex planes show semi-circular,indicating the formation of conductive network.A transition from viscous to elastic behavior was observed for ABS/ graphite composites with the increasing of graphite content.There is a notable change in storage modulus and complex viscosity when the graphite volume fraction is 10.24 ％～ 13.21％,and loss factor (tanδ) peak decreases and shifts to high frequency,meaning a rheological percolation.Due to the shorter graphite-graphite distance required for electrical conductivity as compared to that required to impede polymer mobility,the rheological threshold is smaller than the percolation threshold of electrical conductivity.
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