二氧化硅对碳黑/环氧树脂复合材料渗透特性的影响

通过溶剂化过程制备碳黑-二氧化硅-环氧树脂聚合物基复合材料,并研究复合材料的导电渗透特性。当碳黑的体积分数低于15.5%时,复合材料的导电性可以用经典的渗透理论来描述,并发现渗透阈值约为14.7%,这与理论预测值相接近。当碳黑的体积分数高于15.5%时,材料的电导率与理论预测值偏离较大。这可能是因为:此时材料中的二氧化硅的用量较少,其对碳黑颗粒的空间体积排除效应较差;由于氢键和范德华力作用,纳米级的碳黑颗粒容易形成聚集态,这与渗透理论中导电颗粒必须是单个分布的这一前提假设相违背。扫描电镜分析及模拟计算结果支持该结论。

Effect of Silica on Percolation Characteristics of Carbon Black/Epoxy Resin Composites

Carbon black (CB)-silica-epoxy resin composites were prepared by solvent process and the percolation characteristics of obtained composites were also investigated.When the volume fraction of CB is lower than 15.5%, the electrical conductivity of composites can be described by classic percolation theory.The percolation threshold is found to be 14.7%, which is in good agreement with predicted value.When the volume fraction of CB is over 15.5%, the electrical conductivity of composites deviates significantly from predicted values.This can be ascribed to the generation of CB aggregates via hydrogen bonds and Van Der Waals forces.The formation of aggregates disobeys one of the hypotheses of percolation theory that conductive particles must be mono-dispersed, and results in the deviation of experimental data from theoretical values.The decreasing of silica content lowers the efficiency of its volume excluded effect to CB particles and consequently facilitates the formation of CB aggregates, which is supported by scanning electron microscope (SEM) analyses and molecular simulation results.