蠕变对注塑碳纳米管填充聚合物微观结构及导电性能的影响

Influence of dynamic recovery of molecular chains on the microstructure and property of injection molded carbon nanotube filled-polymer

为了研究黏弹性行为对碳纳米管填充聚合物复合材料微观结构与导电性能的影响,以碳纳米管填充聚丙烯复合材料注塑成型为对象,在不同注塑工艺条件下对制品的近浇口、远浇口部位及其皮-芯层的微观结构及电阻率变化规律进行了观察、测试,并与相同部位退火处理后的试样的微观结构及电阻率进行了对比分析。结果表明,在熔体温度较高的近浇口,高分子链的蠕变回复对碳纳米管在基体中的均匀分布具有明显的诱导调控作用,可以改善该部位的导电性能。类似地,芯层较表层而言,高分子链具有较长的蠕变回复时间,促进了碳纳米管在基体中分布的均匀性,使之具有较高的导电性。退火处理后,制品表层的高分子链发生蠕变回复,诱导碳纳米管在基体中重新分布,消除了高阻皮层,制品导电性能明显改善。研究结果表明,高分子加工过程中的蠕变可以诱导、调控碳纳米管在聚合物基体中的分布状态,是降低皮层电阻率,提高制品导电性能的有效方法之一。

In order to study the effects of processing conditions on the properties of injection-molded carbon nanotubes（CNTs）filled-polymer composites,the skin-core microstructures of the moldings at different locations and their resistivities were studied.Furthermore,the distribution evolution of CNTs in polymer matrix and the resistivity change at mentioned locations during annealing were analyzed.The microstructures observed showed that conductive network developed by CNTs was more uniform and continuous closed to the gate than the one far from it because the molecular chains closed to the gate were in high temperature and presented fast dynamic recovery.As the results of the molecular chains＇ recovery,the resistivity of the molding decreased.During annealing,the resistivity at the skin layer of molding gradually droped with increase of annealing time because of redistribution of CNTs in the matrix induced with the action of such dynamic recovery.The results indicated that it was an effect way to reduce the resistivity of molding,especially to its skin layer,using dynamic recovery process of the molecular chains.