Public Research Seminar by Advanced Materials Thrust, Function Hub -Effect of Foaming on Electrical Properties of Conductive Polymer Composites - Foaming on Electrical Properties of Polymer Composites

This talk presents the effects of foaming on various electrical properties of conductive polymer composites with an emphasis on the EMI shielding. Firstly, the effects of foam parameters on the electrical conductivity will be presented. Previously, it was not fully understood before how the electrical conductivity of conductive filler/polymer composite (CPC) foams varies with bubble growth. But we have developed a theoretical model and clarified the mechanisms by forming a novel resistive network model based on Monte Carlo simulation to directly predict the electrical conductivity of CPC foams. The model predictions agreed very well with the experimental data for both the solid and foamed composites. We have proved that foaming can influence both 1D and 2D conductive filler CPCs. Secondly, the effects of the foam parameters on the EMI SE of the CPC with some newly developed highly conductive MXene materials, magnetic materials, and dielectric materials are presented.  The effects of interfacial structures such as foams and layers on the EMI SE are elucidated. Unlike traditional EMI shielding materials with high reflectivity, foamed CPC decreased the reflectivity and increased the absorptivity significantly and, consequently, very thin EMI shielding materials are developed. Simple 2-layer and 3-layer smart foam structures are proposed with extremely high EMI SE with very low reflectivity and high absorptivity. In summary, the experimental results show that the foaming action will improve the electrical conductivity, the dielectric behavior, the EMI SE, the thermal conductivity, the stretching/bending ability through redistribution of the conductive fillers and their controlled connection with an optimal foam structure.