Universal behavior for electromagnetic interference shielding effectiveness of polymer based composite materials

The electromagnetic interference shielding properties and the electrical properties of poly (methylmethacrylate) (PMMA) based composite materials prepared using different types of fillers (multi-wall carbon nanotubes, carbon black, silver coated glass microfibers) have been investigated in a broad frequency range. By combining a theoretical and an experimental analysis we show that, irrespective of the nature of the conductive material (carbon based or metallic), the correlation between the electromagnetic shielding effectiveness, electrical conductivity and sample thickness follows a universal behavior, all experimental points falling onto a single universal curve predicted by our theoretical analysis. This is demonstrated not only for our own experimental results, but also for numerous experimental data reported in the scientific literature where other types of polymer matrices and other types of fillers have been investigated. The universal relationship found in our study opens the perspective of a precise predictive determination of the electromagnetic interference shielding effectiveness of composite materials based exclusively on their electrical properties. [Display omitted]