石墨烯纳米片在双连续相聚丙烯/高密度聚乙烯中的迁移行为对其导电性能的影响

Influence of Migration of Graphene-nanosheets on the Electrical Behaviors of the PP/HDPE Co-Continuous Phase Blends

通过熔融共混制备了石墨烯纳米片(GNS)/聚丙烯(PP)/高密度聚乙烯(HDPE)导电复合材料。导电行为研究表明,静态热场下复合材料的电阻率随时间延长而下降,并逐渐达到稳定。动态剪切热场作用下,复合材料的电阻率先下降后上升,当180℃剪切8min时,GNS的体积分数为3.4%的50%PP/50%HDPE混合体系电阻率从104Ω·m降低到100Ω·m,下降了4个数量级。剪切时间延长到18min时,其电阻率又升至103Ω·m。超景深显微镜、扫描电子显微镜分析显示,热场作用下GNS从PP基体中向HDPE基体内迁移,且热场+剪切场下的迁移更加明显。通过调控剪切热场的作用时间可有效调节GNS在PP/HDPE双连续相中的分布,进而获得具有较优导电性能的复合材料。

Graphene-nanosheets（GNS）/polypropylene（PP）/high density polyethylene（HDPE）conductive polymer composites with co-continuous structure were prepared by melt blending.The influence of migration of GNS over time on the electrical behaviors of the co-continuous phase blends was also investigated under different fields.The electrical resistivity of the GNS/PP/HDPE blend trends to be stable gradually after a reduction under single thermal field.While,the conductive composites under thermal and shear complex field possess a minimum electrical resistivity with time increasing.A sharp decrease by more than 4orders of magnitude of electrical resistivity of volume fraction 3.4%GNS/PP/HDPE conductive composites,from 104Ω·m to 100Ω·m,is achieved upon the 8min shear at 180 ℃.Interestingly,the electrical resistivity of GNS/PP/HDPE blend sheared at 180 ℃ for 18 min is increased to 103Ω·m.The results of depth digital optical microscopy（DDOM）and scanning electron microscope（SEM）show that the migration of GNS from the PP phase into the HDPE phase under thermal and shear complex field is particularly apparent than that of thermal field alone.This is a consequence of the migration of GNS from PP/HDPE interface to the HDPE phase.Therefore,the appropriate control of the migration and the selective localization of GNS sheets in the multiphase material are key tools in the design of conducting polymer composites.