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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 influence of viscoelastic behavior on the microstructure and electrical conductivity of carbon nanotube-filled polymer composites, carbon nanotubes filled polypropylene composites were used for injection molding. Under different injection molding conditions, The microstructure and the change rule of the resistivity of the gate and the skin of the gate were observed and tested. The microstructure and resistivity of the sample annealed at the same location were compared. The results show that creep recovery of polymer chains near the gate with high melt temperature can induce the uniform distribution of carbon nanotubes in the matrix and can improve the conductivity of the CNTs. Similarly, the core layer has a longer creep recovery time compared to the surface layer, promoting the uniformity of distribution of the carbon nanotubes in the matrix and making it more conductive. After annealing, the polymer chains in the surface of the product undergo a creep recovery, induce the redistribution of the carbon nanotubes in the matrix, eliminate the high-resistance skin layer, and obviously improve the conductivity of the product. The results show that the creep in polymer processing can induce and regulate the distribution of carbon nanotubes in the polymer matrix, which is one of the effective methods to reduce the resistivity of the cortex and improve the electrical conductivity of the product.