Anita Grozdanov, Stefan Kuvendziev, Iva Dimitrievska, Mirko Marinkovski, Martin Stojchevski, Andrea Petanova, Perica Paunović, Duska Kleut, Svetlana Jovanović
In recent decades, due to the rapid development and application of wireless communication, flexible electronics, and smart devices, electromagnetic interference (EMI) and radiation pollution have been intensified, creating an urgent demand for efficient EMI shielding materials. Carbon nanostructures such as graphene and carbon nanotubes are considered promising candidates due to their excellent properties, such as high electrical conductivity, low density, large specific surface area, and flexibility. This work reports our recent results in the design and testing of polymer nanocomposites with irradiated hybrid carbon nanostructure (graphene/multi-walled carbon nanotubes) used as EMI shielding materials. Five representative composites with varying filler loadings (AH of 15% and AM1 of 20 wt%), thicknesses (0.208-0.48 mm), and e-beam irradiation doses (from 50 to 400 kGy) were systematically characterized using SEM, FTIR, TGA/DSC, and vector network analyzer (VNA) measurements in the S-band (2.65-3.90 GHz). The effects of different e-beam irradiation doses and hybrid carbon contents on conductive network construction, interface engineering, and porous or layered structures on EMI shielding performance are discussed. Experimental results show that all studied composites exhibited strong absorption-dominant behavior (SEA), while the multiple reflection component (SEM) was found to be negligible. Both filler loading and sample thickness significantly enhanced shielding performance, with a pronounced synergistic interaction observed between these parameters. A quadratic Response Surface Methodology (RSM) model was developed to correlate the total shielding effectiveness (SET) with thickness and filler content, yielding high predictive accuracy (R2 > 0.96). The model enables efficient optimization of composite design for targeted shielding levels.