短切碳纤维导电复合材料渗流和PTC行为的唯象分析

Phenomenal analysis of percolation and PTC behavior in conducting composite with short carbon fiber

为研究短切碳纤维含量和温度对导电复合材料渗流行为的影响,通过Landau相变理论导出了复合材料电导率与填料体积分数及温度的方程,并用该方程分析了短切碳纤维/乙烯基酯树脂复合材料的渗流和PTC行为。结果表明:复合材料的渗流阈值随温度升高而增加,PTC温度随碳纤维含量增加而上升。当温度由24.6℃上升到108.4℃时,其渗流阈值的理论值由1.06%增加到1.60%;当碳纤维体积分数由3.1%增加到4.6%时,其PTC温度的理论值由120℃上升到170℃。复合材料渗流阈值和PTC温度理论值与实验值符合得很好。

In order to study the effect of the content of the short carbon fiber and the temperature on the percolation behavior of conducting composite, the equations relating the composite conductivity with the filler＇s volume fraction and the temperature were deduced via the Landau phase transition theory. And the percolation transition and PTC behavior in the short carbon fiber/vinyl resin composite were analyzed by these equations. The results show that the percolation threshold of composite increases with temperature as well as the PTC temperature increasing with the content of carbon fiber. The theoretical values of the percolation threshold in composite increase from 1.06% to 1.60% as the temperature from 24. 6℃ to 108. 4℃. And the ones of PTC temperature increase from 120℃ to 170℃ as the volume fraction of carbon fiber from 3. 1% to 4. 6%. The theoretical values of the percolation threshold and PTC temperature in composite fit well with the experimental data.