Simulation Studies Underlying the Influence of Filler Orientation on the Electrical Properties of Short Carbon Fiber Conductive Polymer Composites: Implications for Electrical Conductivity Regulation of Micro/Nanocomposites

The electrical properties of conductive polymer composites are critical in applications, and the electrical conductivity regulation through micro/nanofiller orientation is attracting broad attention. For short carbon fiber (SCF) conductive polymer composites (SCFCPCs), the electrical properties and SCF conductive network topology of SCFCPCs with different SCF orientations are analyzed with a numerical model. The results demonstrate that an increase in the degree of SCF orientation from 0 (SCFs perpendicular to conductivity direction) to 1 (SCFs parallel to conductivity direction) first leads to a corresponding increase and then a decrease in the electrical conductivity of SCFCPCs. The highest electrical conductivity is achieved while the degree of SCF orientation is increased to approximately 0.6, which is a higher SCF orientation state compared to random orientation. Moreover, it is identified that more SCFs in conductive networks do not necessarily guarantee a higher electrical conductivity. The electrical conductivity of the SCF conductive networks also depends on the degree of SCF orientation. Evidently, the less-oriented SCFs tend to build in-layer conductive networks, while the highly oriented SCFs tend to build interlayer ones, which apply a greater contribution to the electrical conductivity. Overall, the results of this study reveal why the highest electrical conductivity occurs at a higher SCF orientation rather than a random SCF orientation. The clarified influence and mechanism provide indications for the electrical conductivity regulation of micro/nanocomposites by adjusting the conductive filler orientation.